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Cell Biology KYCOM block I
Cell Biology KYCOM block I

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__ are the basic structural and functional unit of the body
Cells can be divided into two major compartments:

-The __, the part of the cell located outside of the nucleus, and
-The __, the largest organelle within the cell.
- cytoplasm
- nucleus
The cytoplasm
-Contains __ and __ arranged in an aqueous gel called the __.
-The __ (previous) consists of solutes including __ (Na+, K+, Ca2+) and organic molecules such as __, __, __, __, and __.
-The cell controls the concentration of __ within the cytoplasmic compartment, which influences the rate of __ within the cell.
- organelles; inclusions; cytoplasmic matrix
- cytoplasmic matrix; inorganic ions; metabolites; carbohydrates; lipids; proteins; RNAs
- metabolites; metabolic activity
the nucleus
-Contains the genome and enzymes necessary for __ and __.
- dna replication; rna transcription
All cells have the same basic set of -organelles which can be classified into two groups: __ and __
- membranous (membrane bound) organelles; nonmembranous organelles
- Membranous (membrane bound) organelles that have plasma membranes separating their __ from the __
- Nonmembranous organelles that lack __.
- The spaces enclosed by the organelle membranes make up the __ in which __, __ and other __ are segregated or concentrated
- internal environment; cytoplasm
- plasma membranes
- intracellular microcompartments; substrantes; products; substances
-__ are structures or substances that are not surrounded by a __.
-They can consist of crystals, pigment granules, lipids, glycogen, and other stored __.
- inclustions; plasma membrane
- waste products
-The plasma membrane is now actually classified as a __.
-It is a __ barrier.
-Maintains cell __.
-Regulates __ interactions.
-Carries out specific recognition functions via __ and __.
-Establishes __ for specific molecules.
-Transduces physical or chemical signals into __.
- membranous organelle
- selectively permeable
- structure
- cell-cell
- receptors; antigens
- transport systems
- intracellular events
Plasma membrane
-The current interpretation of the molecular organization of the plasma membrane is now referred to as the __.
-The membrane consists primarily of __, __, and __.
-The phospholipids form a __, with __ properties (it is both hydrophobic and hydrophilic).
-The fatty acid chains of the __ face each other and create a __ domain.
-The surfaces of the membrane are formed by the __ of the phospholipids and create a __ domain.
- modified fluid mosaic model
- phospholipids, cholesterol, proteins
- lipid bilayer; amphipathic
- phospholipids; hydrophobic
- polar heads; hydrophilic
Plasma Membrane
-__ account for approximately half of the total membrane mass in most membranes.
-Most of the proteins embedded in the membrane span the lipid bilayer __; these proteins are the __
-__ are not embedded in the membrane and are associated with the membrane by strong __, mainly with __.
- proteins
- completely; integral proteins
- peripheral membrane proteins; ionic; integral proteins
-Carbohydrates may be attached to the proteins on the extracellular surface of the membrane, forming __.
-Carbohydrates can also be attached to the lipids, forming __.
-These surface molecules make up a layer on the cell surface that is referred to as the cell coat or __.
-__ and __ have specific functions in metabolism, cell recognition, cell association, and serve as receptor sites for hormone
- glycoproteins
- glycolipids
- glycocalyx
- glycoproteins; glycolipids
-The __ can be seen projecting from the microvilli of this absorptive cell from the intestine.
-Glycoproteins here include digestive enzymes such as __ and __
- glycoproteins
- dipeptidases; disaccharidases
-Microdomains of the plasma membrane known as __ control the movement and distribution of __ within the lipid bilayer.
-Recent research has indicated that the distribution and movement of proteins within the lipid bilayer is not as random as was once believed.
-Localized regions within the plasma membrane contain high concentrations of __ and __, called __.
-The __ (previous) is __ and exhibits less __ than the surrounding membrane.
-The diminished fluidity is due to the presence of __ and the presence of longer, highly __
- lipid rafts; proteins
- cholesterol; glycosphingolipids; lipid rafts
- lipid raft; thicker; fluidity
- cholesterol; saturated fatty acid chains
-Lipid rafts contain various integral and peripheral proteins involved in __.
-Each raft is equipped all of the elements necessary to receive and convey __.
-These elements include receptors, coupling factors, effector enzymes, and substrates.
-__ in lipid rafts occurs more rapidly and efficiently because of the close proximity of the __.
- cell signaling
- specific signals
- signal transduction; interacting proteins
-Integral membrane proteins can be visualized by a special technique known as __.
-When tissue is prepared for electron microscopy, membranes typically split along the __ plane.
-This exposes the two faces of the membrane, the __ and the __.
-The __ is backed by the extracellular space, while the __ is backed by the cytoplasm
-Usually the P-face displays more __ than the E-face.
- freeze fracture
- hydrophobic
- E-face; P-face
- E-face; P-face
- particles (i.e. proteins)
-__ have important functions in cell metabolism, regulation, and integration.
-There are __ broad categories of membrane proteins that have been defined.
-The categories are not mutually exclusive, meaning that a structural membrane protein may simultaneously act a receptor, an enzyme, a pump, or any combination of these functions
-integral membrane proteins
- six
-__ – transport ions such as Na+ across the membrane as well as macromolecule precursors.
-__ – allow the passage of small ions, molecules, and water across the membrane in both directions. __ are a type of channel (more on that later).
-___ – allow recognition and localized binding of ligands in processes such as hormonal stimulation, coated-vesicle endocytosis, and antibody reactions
- pumps
- channels; gap junctions
- receptor proteins
-__ – anchor the intracellular cytoskeleton to the extracellular matrix. Examples of these include the __ that link cytoplasmic actin to an extracellular matrix protein (fibronectin).
-__ – include ATPases involved in ion pumping, ATPase synthase in the inner mitochondrial membrane, and digestive enzymes such as dipeptidases and disaccharidases.
-__ – visualized by the freeze fracture method, especially where they form junctions with neighboring cells.
- linker proteins; integrins;
- enzymes
- structural proteins
-Substances that either enter or exit must pass through the __.
-Some substances (__ and small, __) cross the membrane by __.
-All other molecules require ___ to provide them with a passage.
- membrane
- (fat soluble and small, uncharged molecules); simple diffusion
- membrane transport proteins
-__ – transfer small, water-soluble molecules.
-They are very __ and often transport only one type of __.
-After binding to a molecule that will be transported, the carrier protein undergoes __ and releases the __ on the other side of the membrane.
-Some carrier proteins such as the __ pump require energy for the active transport of substances against their concentration gradient.
-Other carrier proteins, such as glucose carriers, do not require energy and participate in __
- carrier proteins
- selective; molecule
- conformational changes; molecule
- sodium postassium
- passive transport
-__ – also transfer small, water-soluble molecules.

-Channel proteins create __ through the plasma membrane that regulate the __ of the molecule.
-Channel protein transport can be regulated by membrane potentials (voltage-gated ion channels in neurons), __ (ligand-gated ion channels such as acetylcholine receptors in muscle cells), or __ (mechanically-gated ion channels in the inner ear).
- channel proteins
- hydrophilic channels; transport
- membrane potentials, neurotransmitters; mechanical stress
-__ maintains the integrity of the plasma membrane and provides for the transfer of molecules between different cellular compartments.
-This process involves __ in the plasma membrane at localized sites and the subsequent formation of __ or fusion of vesicles with the membrane.
-Vesicular transport can be described in more specific terms __ and __
- vesicular transport
- configurational changes; vesicles;
- endocytosis; exocytosis
__ brings molecules and other substances into the cell that would otherwise be too large to pass through the membrane
-__ is essentially the reverse of endocytosis
-A vesicle moves from the __ to the __ where it discharges its contents to the __
- exocytosis
- cytoplasm; plasma membrane; extracellular space
receptor mediated endocytosis
-When ligands bind to their receptors, the receptors become __ into __.
-The coated pit __ and forms a __ that transports the __, into the cell.
-The coated vesicles fuse with __, a system of vesicles and tubules located in the cytosol near the cell surface.
-The __ in the endosomes allows for the separation of the __ and their receptors.
-Ligands are typically sent to __, while their __ are returned to the __.
- aggregated; coated pits
- invaginates; coated vesicle; ligand
- endosomes
- low pH; ligands
- lysosomes; receptors; cell membrane
- __:Small invaginations of the cell membrane form to trap extracellular fluid and any molecules contained in that fluid.
-- sometimes referred to as __
- __: this literally means cell eating
--Certain cells such as __ and polymorphonuclear leukocytes are specialized for engulfing and removing bacteria, protozoa, fungi, damaged cells and other cellular trash.
- pinocytosis
-- cell drinking
- phagocytosis
-- macrophages
- __:These organelles are sites of intracellular digestion and turnover of cellular components
- __ (previous) are membrane bound vesicles that contain a variety of __
-The __ of lysosomes are resistant to the hydrolytic digestion that occurs inside the organelle
- the most common enzymes are __, __, __, and __
-These enzymes are responsible for the degradation of macromolecules derived from __ pathways and __ (removal of organelles
- lysosomes
- lysosomes; hydrolytic enzymes
- membranes
-proteases, nucleases, lipases, and phospholipases.
- endocytotic ; autophagy
Lysosomal function
-Synthesized in the __; their enzymes are packaged in the __
-Contents of secondary lysosomes can be __ or can remain in the cell as __.
- in some cells, __ can be excreted
- RER; golgi complex
- excreted; residual bodies
- lysosomal enzymes
Lysosomal Storage Diseases
- Lysosomal diseases are caused by __
- The result is an accumulation in cells of __ used in __
- there are __ lysosomal storage diseases
- defective lysosomal enzymes
- specific substrates; lysosomal enzymatic reactions
- 49
-Children born with lysosomal storage diseases usually appear __ at birth, then clinical signs of disease begin to appear
-These children grow __, show changes in __, and develop bone and joint deformities leading to __.
-They may loose already attained skills such as __ and __
- __ and __ may occur
-These children are prone to __ infections, __ disease, and __ of internal organs, such as the liver and spleen (hepatosplenomegaly).
- normal
- slower; facial features; restrictions of limb movements
- speech; learning ability
- behavioral problems; mental retardations
- lung; heart; enlargement
-____ is characterized by the deficiency of β-hexosaminidase, which results in the accumulation of gangliosides in the central nervous system.
- the accumulation of __ interferes with the normal functioning of cells
- tay-sachs disease
- gangliosides
-The most common lysosomal storage diseases are __, __, and __
- gaucher disease; hunter syndrome; pompe disease
-Gaucher disease – characterized by the defective activity of a __, which results in the accumulation of __ in the __, __, and __.

-Gaucher disease is now treated with __.
- glucocerebrosidase;glucocerebrosides; spleen; liver; cns
- enzyme replacement therapy
-__ consist of two subunits that are composed of four types of rRNA and almost 80 different proteins.
-The RNA of both subunits are synthesized in the __.
-Subunits leave the nucleus via __
-Ribosomes play an important role in translating __ in protein synthesis
- nucleus
- nuclear pores
- mRNA
-Individual ribosomes are held together by a strand of __ to form __.
-__ synthesized for use in the cytoplasm are synthesized on polyribosomes existing as isolated clusters in the cytoplasm.
-Polyribosomes attached to membranes of the __ translate __ that code for proteins that are secreted or stored in the cell.
- mRNA; polyribosomes
- proteins
- ER; mRNAs
- __:This is a membrane system that consists of interconnected sacs and channels that enclose a space called the __
-There are two types:
1.__ – cytosolic side is covered with polyribosomes
2.__ – lacks associated polyribosomes
- endoplasmic reticulum; cisterna
1. rer
2. ser
ser is involved in the following processes
1. steroid and lipid metabolism
2. glycogen metabolism
3. membrane formation and recycling
4. detoxification and conjugation of noxious substances
SER is specialized in __, where it is called the __; responsible for sequestering __.
muscle; sarcoplasmic reticulum; calcium
-The function of the __ is to complete posttranslational modifications, package and place an address on products synthesized by the cell.
-It is composed of smooth membrane-limited __ that appear as flattened sacs.
- golgi apparatus (complex)
- cisternae
golgi apparatus
-The cis or forming face receives several types of molecules produced in the __.
-After processing, these molecules are released from the __ face in larger vesicles that constitute __, lysosomes or other cytoplasmic components
- trans; secretory granules
-__ is a rare inherited disorder characterized by poor physical growth and mental retardation.
-It is caused by a deficiency of __, a phosphorylating enzyme, normally present in the Golgi Apparatus.
-__ are not separated to form lysosomes and are secreted.
-The __ of these patients are empty.
-Cells show large __ granules that interfere with cellular metabolism.
- I-cell disease (inclusion cell disease)
- phosphotransferase
- nonphosphorylated proteins
- lysosomes
- inclusion
-__:The organelle that transforms the chemical energy of metabolites in the cytoplasm into energy for the cell.
-Around 50% is stored as high energy phosphate bonds in __.
-The remaining 50% is dissipated as __ for body temperature maintenance.
-This organelle has a __ membrane.
-Mitochondria also have __ DNA.
- mitochondria
- atp
- heat
- double
- circular
-Mitochondria contain the enzyme system that generates ATP via the __ and __.
-__ is a large membrane-bound enzyme found in the inner mitochondrial membrane.
- citric acid cycle (krebs cycle); oxidative phosphorylation
- ATP synthase
-__ is found in the inner mitochondrial membrane.
-This membrane has a series of infoldings called __.
- atp synthase
- cristae
-Mitochondria are transmitted by the __
-Both males and females can be affected by mitochondrial diseases, but __ can not transmit the disorder.
-__ do not transmit mitochondria at fertilization.
- mother (maternal inheritance)
- males
- males
mitochondrial diseases
- MERRF: __
- this disease is characterized by generalized __, loss of __, and multiple ___
- the major complications are __ and __ because the __ and __ muscles are affected
- histologically, __ appear ragged due to aggregations of abnormal __
- myoclonic epilepsy with ragged red fibers
- muscle weakness; coordination (ataxia); seizures
- cardiac; respiratory failure; cardiac; respiratory
- red muscle fibers; mitochondria
There are three maternally inherited mitochondrial diseases that affect males more severely than females:
1. Leber's hereditary optic neuropathy (LHON)
2. male infertility
3. pearson marrow-pancreas syndrome
leber's hereditary optic neuropathy
-__ of the affected individuals are male.
-The disease is confined to the __.
-Affected individuals suffer a sudden loss of vision in the __ of life
- eye
- second and third decades
male infertility
- almost all the energy for sperm motility is derived from __
- mitochondria
pearson marrow pancreas syndrome
- __ and __ observed in childhood
- anemia; mitochondrial myopathy
- peroxisomes: __ shaped organelles.
-Peroxisomes oxidize specific organic substances by removing __ ions and transferring them to oxygen. This process produces __, an extremely toxic substance.
-__, an enzyme that breaks down hydrogen peroxide, is contained within peroxisomes.
-Peroxisomes also contain __ and __ involved in lipid metabolism
- spherically
-hydrogen; hydrogen peroxide
- d-amino acid oxidases ;beta oxidation enzymes
-Peroxisomes in the liver perform a variety of __ processes.
-Peroxisomes in liver cells (hepatocytes) are responsible for the detoxification of __ by converting it to __.
-Peroxisomes are abundant in the __ and __ (they are found in other cells, too).
-The number of peroxisomes can __ in response to diet, drugs, and hormonal stimulation.
- detoxification
- alcohol; acetaldehyde
- liver; kidney
- increase
There are various disorders caused by the inability to import proteins into __ because of faulty targeting signals or receptors
-Zellweger syndrome is the most commonly inherited peroxisomal disease.

-Zellweger syndrome is a rare, __ disease that is lethal within the __ of life.
-The syndrome belongs to a group known as the __, that affect __ formation in the axons of the brain.
-Zellweger syndrome is characterized by a reduction or absence of peroxisomes in __, and cells of the __ and __
- zellweger syndrome
- congenital; first year
- leukodystrophies; myelin
- hepatocytes; kindney; brain
zellweger syndrome
-Zellweger syndrome is caused by the mutation of the __, which encodes the receptor for the peroxisome targeting signal (it does not recognize the Ser-Lys-Leu at the carboxy-terminus of enzymes directed toward peroxisomes).
-The clinical characteristics include __, high levels of __ and __ in the blood, and defective __.
-Children may be unable to __ or __ or __
- PXRI gene
- hepatomegaly (liver enlargement), iron; copper; vision
- move; suck; swallow
-The __ is a complex network of microtubules, actin filaments (microfilaments) and intermediate filaments.
--Helps maintain the __ of the cell, plays a role in the __ of organelles and vesicles and also participates in the movement of entire cells.
-__ help move organelles.
-__ functions include anchoring and movement of membrane protein, formation of the structural core of microvilli, cellular locomotion, extension of cell processes.
-__ have a general support or structural role
-- shape; movement
- microtubules
- actin
- intermediate filaments
Kartagener's syndrome
-Defects in the organization of __ and microtubule-associated proteins can immobilize __ of the respiratory epithelium.
-Accumulated secretions and mucus cannot be cleared causing __
-Dysfunction of microtubules can cause problems with __ in men, which can cause infertility because the flagella are affected.
-In women, __ in the uterine tubes can cause infertility.
-In addition, __ of internal organs may be seen in individuals with Kartagener’s syndrome.
-This side reversal is called __.
-microtubules; cilia
- chronic respiratory infections
- sperm motility
- ciliary transport of the ovum
- side reversal
- situs inversus
- __:Membrane-limited compartment that contains the genome
-- components include: __, __, __, and __
- nucleus
-- chromatin; nucleolus; nuclear envelope; nucleoplasm
-Chromatin: Complex of __ and __
-In non-dividing cells, the chromatin is in various degrees of __ or __
- the degree of condensation results in two kinds of chromatin observed by light and electron microscopy, these are __ and __
- dna; proteins
- coiling; condensation
- heterochromatin; euchromatin
- heterochromatin
--is the __ form
-- on EM looks like ___
-- on LM looks like __
- euchromatin
-- is the __ form
-- on EM looks like __
-- on LM looks like __
-- more condensed form
-- coarse electron dense granules
-- basophilic clumps
-- less condensed
-- finely dispersed granular material
-- lightly stained basophilic areas
chromatin structure
- __ is the basic structural unit
-- 2 loops of __ wrapped around a core of __ with a linking __
-- beads on a string
- __ chromatin fibril
-- __ coiled around an axis
-- __ per turn
- nucleosome
-- dna; 8 histone proteins; 2nm filament of dna
- 30 nm
-- nucleosomes
-- six nucleosomes
chromosomes: human cells
- humans have __ chromosomes, arranged in __ homologous pairs.
-- the pairs can be divided into __ pairs of autosomes and __ pairs of sex chromosomes
- 46 chromosomes is the __ number
- dna content of the __ chromosomes
- 46; 23
-- 22; 1
- diploid (2n)
- diploid (2d)
-Chromosomal structure can be studied by examining stained __
- ___: Chromosomes sorted by size, shape, and staining pattern
--Can reveal __ in chromosome number or structure
- metaphase chromosomes
- karyotype
-- alterations
- sex chromatin: Also called __
-__ mass observed in __ cells but not __ cells
--Represents a tightly coiled __
--Visible as a small granule attached to the __ of __ cells (esp. buccal smears) and as a “drumstick” appendage to the nucleus of __
- barr body
-heterochromatin; female; male
-- X chromosome
-- nuclear envelope; epithelial; neutrophilic leukocytes
-nucleolus: Site of __ and initial __
-Non-membranous region that surrounds transcriptionally active __ genes
-Nucleoli vary in __
-More than __ may be present in a cell
- ribosomal RNA synthesis; ribosome assembly
- rRNA
- size
- 1
- there are 3 morphologically distinct regions in the nucleolus: __, __, and __
- Fibrillar centers; fibrillar material; granular material
-Fibrillar centers: Contain __ loops of chromosomes containing __ genes
-Fibrillar material: __ genes being actively __, Large amounts of __
-Granular material: Densely packed __ particles
- dna; rRNA
- rRNA; transcribed; rRNA
- preribosomal
-__:Separates the nuclear compartment from the cytoplasm
-Formed by 2 membranes with a __ between them
--Cisternal space is continuous with the cisternal space of the __
--Envelope is perforated by __
- nuclear envelope
- perinuclear cisternal space
-- rer
-- nuclear pores
-Outer nuclear membrane
--Resembles and is continuous with __ membrane
--May have __ on cytoplasmic surface
-Inner nuclear membrane
--Supported by the __
--Contains receptors that bind the __ and __
-- rer
-- ribosomes
-- nuclear lamina
-- lamina; chromosomes
- nuclear lamina: Network of __ having a __ function
--Serves as a __ for chromatin, chromatin-associated proteins, nuclear pores, and membranes of the nuclear envelope
- protein filaments; supporting
- scaffolding
- nuclear pores: 70-80 nm openings formed by the merging of the __ and __
-Each pore contains a __ complex consisting of __ that mediate transport in and out of the nucleus
--Large proteins and macromolecular complexes are transported by a __
--Small molecules may cross water-filled channels by __
--Small __ may also be selectively transported
- inner; outer nuclear membranes
- nuclear pore; proteins
-- GTP dependent mechanism
-- diffusion
-- proteins
- __: Material enclosed by the nuclear envelope exclusive of the chromatin and nucleolus
-- includes __, __, and __
-- nucleoskeleton, nuclear lamina, and rna transcription and processing machinery
- __: Self-regulated sequence of events that controls cell growth and cell division
-- two principal phases include __ and __
-- __: partitioning of the genome
-- __: represents growth of the cell
- cell cycle
-- interphase and M phase (mitosis)
-- m phase (mitosis)
-- interphase
- interphase is further divided into 3 phases: __, __, and __
-- checkpoints control progression through the cell cycle
- G1; S; G2
- G1
-- gathers __
-- synthesis of __ and __
-- cell __ restored
-- nutrients
-- RNA; proteins
-- volume
-G1 Checkpoints
--__: Most important checkpoint (point of no return)
--Mediated by __ and __
-G1 DNA damage checkpoint
--Tumor suppressing protein __ mediates
--High p53 __ cell cycle
-Cell may leave the cell cycle and enter __ or undergo programmed cell __
- restriction point
- retinoblastoma susceptibility protein (pRB); essential transcription factors (E2F)
-- p53
-- arrests
- G0; death
-- __ is replicated
-- __ checkpoint
-- dna
-- S dna damage
G2 cell cycle
-Accumulation of __
-__ synthesis
-Synthesis of chromosomal __
-G2 DNA damage __
-__ DNA checkpoint
- energy
- tubulin
- nonhistone proteins
- checkpoint
- unreplicated
M (mitosis)
- includes __ and __
- __ assembly checkpoint
- __ segregation checkpoint
- karyokinesis; cytokinesis
- spindle assembly
- chromosome
-Failure of cell cycle checkpoints to function properly may lead to __ cell development
-Mitotic catastrophe (abnormal chromosome segregation) may lead to __
-Restriction point failure may lead to __ inhibition
- tumor
-- aneuploid cells
-- loss of contact
-Passage through the cell cycle is driven by __ that are cyclically synthesized and degraded
-Two-protein complexes consisting of a __ and a __ power cells through checkpoints of the cell cycle
- proteins
- cyclin; cyclin dependent kinase
- __:Process of nuclear and cellular division where a parent cell produces two daughter cells with sets of chromosomes identical to that of the parent cell
-- what are the 4 phases of mitosis
-- prophase, metaphase, anaphase, telephase
-Chromosomes condense and become visible
--Sister chromatids are held together by __ and the __
-__ migrate to opposite poles
-__ disappears
-__ forms
-A __ forms on each chromatid
-__ disassembles
- chromosomes
-- cohesions; centromere
- centrosomes
- nucleolus
- mitotic spindle
- kinetochore
- nuclear envelope
--Chromosomes migrate to the __
--__ spindle organizes around the __-organizing centers
--__ attach at the kinetochores
--__ separate and are pulled toward __ of the cell
-- equatorial plane
-- mitotic spindle; microtubule
-- microtubules
-- sister chromatids; opposite poles
-__ is reconstituted around the chromosomes at each pole
-__ uncoil
-__ reappears
--Ring of __ and __ filaments around the perimeter of the cell contracts and pinches the cell into 2 daughter cells
- nuclear envelope
- chromosomes
- nucleolus
- actin; myosin II
-__:Two sequential cell divisions that produce gametes containing half the number of chromosomes and half the DNA found in somatic cells
- resulting cells are genetically __
-- segregation of __ and __ chromosomes
-- __ achieves genetic recombination
- meiosis
- unique
-- paternal; maternal
-- crossing over
-Phases of meiosis are similar to the phases of __
-No __ between the successive divisions
-Progression of chromosome number and DNA content
--2n, 4d at start of meiosis after an S phase
--1n, 2d after meiosis I
--1n, 1d after meiosis II
- mitosis
- S phase
meiosis: prophase I
- __ phase of 5 stages
- events include __, __, and __
--__: Chromatin condensation and pairing of homologous chromosomes
--__: Synapsis, formation of the synaptonemal complex
--__: Crossing-over
- extended
- pairing; synapsis; recombination
-- leptotene
-- zygotene
-- pachytene
- Diplotene
-- __ dissolves
-- __ condense further
-- __ appear
- diakinesis
-- __ condensation
-- __ disappears
-- __ disintegrates
--synaptonemal complex
-- chromosomes
-- chiasmata
-- maximum chromosome
-- nucleolus
-- nuclear envelope
-Metaphase I
--Paired chromosomes align at __
--__ breakdown
-Anaphase I
--__ does not split, sister chromatids stay together
Members of each homologous pair moves to __
--- also called ___
-- equatorial plate
-- chiasmata
-- centromeres
-- opposite poles
--- random assortment
Telophase I
- __ reforms
- __ divides
- produces daughter cells that are __,__
- nuclear envelope
- cytoplasm
- 1n, 2d
Meiosis II
-After meiosis I, cells __ enter meiosis II
-Essentially a __
-A 1n, 2d cell becomes two __, __ daughter cells
-Unlike mitosis, the daughter cells are not __
- quickly
- mitosis
- 1n, 1d
- genetically identical
-__ may result from accidental cell injury or mechanisms that causes cell to self-destruct
--__ cell death
--__ process
--Unfavorable physical or chemical environment
---Acute cellular injury and damage to the plasma membrane
---Rapid cell __ and __ are characteristic
- cell death
-- accidental
-- pathological
--- swelling; lysis
-Apoptosis (programmed cell death)
--Physiologic process
--Cells that are no longer needed are __
--Cells initiated an internally encoded program for apoptosis
--A variety of __ or __ signals can initiate apoptosis
--Process is very __
-- extrinsic; intrinsic
-- rapid
apoptosis:Characteristic morphologic and biochemical features
-DNA fragmentation
--__ event
--__ aggregates, __ may fragment
-Decrease in cell volume
--__ reorganizes
--__ clump, __ forms whorls, __ vesicles fuse with plasma membrane
-- irreversible
-- chromatin; nucleus
-- cytoskeleton
-- ribosomes; rer; endocytotic
-Loss of mitochondrial function
--Change in membrane permeability
--___ disrupted
--__ is released into the cytoplasm
---Activate __
---___ dismantle the cell
-Membrane blebbing
--___ alterations
--Leads to __ without loss of integrity
---Cell contents remain contained
-- etc
-- cytochrome c
--- caspases
--- caspases
-- plasma membrane
-- blebbing
formation of apoptotic bodies
- cell breaks into __
- rapidly removed by __ cells
-- no __ response is elicited
- membrane bound vesicles
- phagocytic cells
-- inflammatory
gemetogenesis: Conversion of germ cells into __ and __
-Primordial germ cells are formed in the __ during the __ and move to the wall of the __
-During the __, they migrate from the __ to the developing __ where they arrive by the end of the __
- __ increase their numbers during migration and in the gonad
- Germ cells undergo __ in preparation for __
--__ to reduce chromosome number
--__ to complete maturation
male; female gametes
- epiblast;second week; yolk sac
- fourth week; yolk sac; gonads; fifth week
- mitotic divisions
- gametogenesis; fertilization
-- meiosis
-- cytodifferentiation
- __:Nuclear events, while different in timing, are similar in male and female gamete formation
-__:Cytoplasmic events are quite different
--Females produce __
--Males produce __
- meiosis
- cytodifferentiation
-- mature oocytes
-- spermatozoa
-Primordial germ cells differentiate into __
-Oogonia undergo __
--By the end of the __, oogonia are arranged in clusters surrounded by a layer of __ derived from the __
- oogonia
- mitotic divisions
-- third month; flat epithelium cells; surface epithelium of the ovary
-Oogonia continue to divide by __
--Some enter __ and arrest in __ becoming __
--In the __ the number of germ cells in the ovary reaches __
--At this time __ begins, many __ and __ are lost
--By the __, most __ are gone
- mitosis
-- meiosis; prophase I; primary oocytes
-- fifth month; its maximum (about 7 mil)
- atresia; oogonia; primary oocytes
- seventh month; oogonia
-The surviving __ (in __) are now individually surrounded by a layer of __
--These structures are the __
--__ remain arrested in the __ stage of prophase I and do not complete meiosis I until after __ is reached
--Numbers of primary oocytes
---__ to __ at birth
---__ at beginning of puberty
---Fewer than __ will reach ovulation as secondary oocytes
- primary oocytes; (prophase I); flat epithelial cells
-- primordial follicles
-- primary oocytes; diplotene; puberty
--- 400,000
--- 500
- follicular growth and maturation
-- at puberty a pool of __ is established
---Each month __ begin to grow
---The epithelial cells change from __ to __ and begin to proliferate producing a __ (__)
---The growing follicles are now called __
-- growing follicles
---15-20 primordial follicles
--- flat; cuboidal; stratified epithelium (granulosa cells)
--- primary follicles
-Primary follicles
--The cells of the __ surrounding the growing follicle organize into the __
--The __ cells and the __ secrete a glycoprotein layer around the oocyte called the __
---__ from the granulosa cells and oocyte extend across the __ to transport materials to the __
-- ovarian stroma; theca folliculli
-- granulosa; oocyte; zona pellucida
--- cytoplasmic projections; zona pellucida; oocyte
Secondary follicle
-As the follicle grows fluid filled spaces develop between the __
--These spaces coalesce into a singe space called the __
-The oocyte is found on the edge of __ surrounded by __, the __
- granulosa cells
-- antrum
- antrum; granulosa cells (granulosa cells = follicular cells); cumulus oophorus
- mature follicle
-- only __ reaches maturity each ovarian cycle
---The other maturing follicles undergo __
--Mature follicles are often __ or more in diameter
-- one follicle
--- atresia
-- 25mm
-A surge of __ induces the __ of the __ to complete __
--The __ is unequally divided between the daughter cells producing one __ with most of the cytoplasm and the first __ with little cytoplasm
--The polar body lies between the __ and the __ in the __
-After meiosis I, the __ enters meiosis II but arrests during __ about __ prior to ovulation
--Meiosis II will complete only if the __ is __
--Without __ the oocyte degenerates about 24 hours after ovulation
- luteinizing hormone (LH); oocyte; mature follicle; meiosis I
-- cytoplasm; secondary oocyte; polar body
-- secondary oocyte; zona pellucida; perivitelline space
- secondary oocyte; metaphase; 3 hours
-- oocyte; fertilized
-- fertilization
-At birth, primordial germ cells and supporting cells are present in the __ of the __
--Supporting cells, derived from the __ of the __, will develop into __, or __
-Shortly before puberty
--The sex cords acquire a __ and become the __
--Primordial stem cells give rise to __
- sex cords; testis
-- surface epithelium; testis; sustentacular cells; sertoli cells
-- lumen; seminiferous tubules
-- spermatogonial stem cells
-At regular intervals, cells emerge from the spermatogonial cell population to form __
--This marks the beginning of __
-__ undergo a limited number of mitotic divisions
--The last division produces __
-__ then divide to form __
- type A spermatogonia
-- spermatogenesis
- type A spermatogonia
-- type B spermatogonia
- type B spermatogonia; primary spermatocytes
-Primary spermatocytes enter a __ followed by rapid completion of __ producing __
-__ then undergo meiosis II producing __
- prolonged prophase (22 days); meiosis I; secondary spermatocytes
- secondary spermatocytes; spermatids
-Transformation of __ into __
--Formation of the __
--Condensation of the __
--Formation of the __ and __
--Shedding of __
- spermatids; spermatozoa
-- acrosome
-- nucleus
-- tail; related structures
-- cytoplasm
-__ and __ remain embedded in recesses of __ throughout their development
--__ support and protect the germ cells
-Spermatogenesis is regulated by __ production
--All progeny of a single __ remain connected by cytoplasmic bridges
- spermatogonia; spermatids; sertoli cells
-- sertoli cells
- luteinizing hormone
- type A spermatogonium
-Half of all spontaneous abortions have a major __, which include:
--45, X
--Trisomy 16
-Chromosomal abnormalities account for __ of major birth defects
- chromosomal defect
-- 45, X
-- Triploidy
-- Trisomy 16
- 7%
- __: extra or missing chromosome
-- arise from __ during cell division
---__ gives rise to abnormal gametes
---__ gives rise to mosaicism
- numerical
-- nondisjunction of chromosomes
--- meiosis
--- mitosis
-Clinical syndromes
--Down syndrome: __
--Trisomy 18
--Trisomy 13
---Usually nondisjunction of the XX homologues
---80% due to nondisjunction in the male gamete
Triple X syndrome
-- trisomy 21
-- klinefelter syndrome: XXY
-- Turner syndrome: 45, X
-Translocations: pieces of one chromosome attach to another
--__: no critical material lost
---Normal phenotype
--__: part of chromosome is lost
---Abnormal phenotype
--Gene level problems without loss of material can also arise from translocations
- translocations
-- balanced
-- unbalanced
-__: loss of part of a chromosome
--__ syndrome: partial deletion of 5p
-__: span only a few contiguous genes
--__: deletion of 15q11-15q13
-Fragile sites
--Fragile X syndrome: Xq27
- deletions
-- cri-du-chat syndrome
- microdeletions
-- angelman syndrome/prader-willi syndrome
down syndrome: trisomy 21
-95% caused by __
--75% in __
---Increasing risk with __
1:2000 if <25
1:300 at age 30
1:100 at age 40
-4% __
--Chromosome 13,14, or 15
-1% __ due to mitotic nondisjunction
- meiotic nondisjunction
-- oocyte
--- maternal age
- unbalanced translocation
- mosaicism
-As the __ undergoes the final steps of maturation, a bulge appears on the surface of the ovary
--An __ appears at the apex called the __
-- high __ results in increased collagenase activity digesting the __ around the follicle
- follicle
-- avascular spot; stigma
-- LH concentration; fibers
-The oocyte and granulosa cells of the __ break free from the __ and are extruded from the ovary
--The granulosa cells arrange into the __
-Corpus luteum
--The __ cells remaining in the ruptured follicle wall and the __ cells change into __ cells
--The area is vascularized forming the __
--Secretes __ which acts on the __ in preparation for implantation
- cumulus oophorus; follicle wall
-- corona radiata
-- granulosa; theca interna; lutean
-- corpus luteum
-- progesterone; uterine mucosa
oocyte transport
-At ovulation the fimbriae of the __ move over the surface of the __
-Sweeping motions of the __ and __ movement of the tube lining carry the __ into the tube
--The __ cells withdraw their processes from the __
--A fertilized oocyte takes __ to reach the uterine cavity
- uterine tube; ovary
- fimbriae; ciliary; oocyte
-- granulosa; zona pellucida
-- 3-4 days
-Fertilization normally occurs in the __ of the __
-Spermatozoa reach the __ primarily by their own __
--Spermatozoa may survive in the female reproductive tract for __
--1% of spermatozoa deposited in the vagina enter the __
--It takes 2-7 hours to migrate from the __ to the __
--Upon reaching the __ of the tube the spermatozoa become less __ and stop their __
- ampulla; uterine tube
- ampulla; propulsion
-- several days
-- cervix
-- cervix; uterine tube
-- isthmus of the tube; motile; migration
-At ovulation, the __ become motile again and swim to the __
-Spermatozoa must undergo __ before becoming capable of fertilization
--__ in the female reproductive tract
--Mostly occurs in the __
--Lasts about __
--A __ coat and __ are removed from the plasma membrane overlying the __
- spermatozoa; ampulla
- capacitation
-- conditioning
-- uterine tube
-- 7 hrs
-- glycoprotein; seminal plasma proteins; acrosome
three phases of fertilization
1. penetration of the corona radiata
2. penetration of the zona pellucida
3. fusion of the oocyte and spermatozoon membranes
phase 1: penetration of the corona radiata
--Only __ reach the site of fertilization
--Only one will fertilize the __
--__ easily penetrate the __
-- 300-500 spermatozoa
-- oocyte
-- capacitated spermatozoa; corona radiata
Phase 2: Penetration of the Zona Pellucida
-__ bind to __ of the zona pellucida
-The acrosomal reaction culminates with the release of ___ to penetrate the __ of the zona pellucida
-When the spermatozoon contacts the __, the oocyte releases enzymes from __ that alter the __ and __ to prevent further penetration of the oocyte or binding to the zona pellucida
- spermatozoa; ligand proteins
- acrosomal enzymes; glycoprotein shell
- oocyte plasma membrane; cortical graules; plasma membrane; zona pellucida
-Phase 3: Fusion of the __ and __ membranes
--After adhesion to the surface of __ by the __, the membranes of each fuse
--The __ and __ of the spermatozoon enters the __ of the oocyte
-Phase 3: Fusion of the oocyte and spermatozoon membranes
--After adhesion to the surface of oocyte by the spermatozoon, the membranes of each fuse
--The head and tail of the spermatozoon enters the cytoplasm of the oocyte
-The entry of the spermatozoon triggers:
--__ and __ reactions
--Resumption of the __
---Produces the definitive __ and the __
---The chromosomes arrange into the female ___
--Metabolic activation of the oocyte
---Initial cellular and molecular events of __
-The entry of the spermatozoon triggers
--Cortical and zonal reactions
--Resumption of the second meiotic division
---Produces the definitive oocyte and the second polar body
---The chromosomes arrange into the female pronucleus
--Metabolic activation of the oocyte
---Initial cellular and molecular events of embryogenesis
-- oocyte
--- embryogenesis
-The __ moves close to the female __
--Its nucleus swells forming the __
--The __ detaches and degenerates
-Each __ replicates its DNA
-After DNA replication the chromosomes of both __ organize on a spindle in preparation for a __
--Each of the two resulting cells of the zygote have a __ chromosome number and DNA content
-The spermatozoon moves close to the female pronucleus
--Its nucleus swells forming the male pronucleus
--The tail detaches and degenerates
-Each pronucleus replicates its DNA
-After DNA replication the chromosomes of both pronuclei organize on a spindle in preparation for a mitotic division
--Each of the two resulting cells of the zygote have a diploid chromosome number and DNA content
The main results of fertilization:
-Restoration of the __ number of chromosomes
--Half from the mother; half from the father
-Determination of __
--__ carrying spermatozoon produces female embryo
--__ carrying spermatozoon produces male embryo
-Initiation of __
The main results of fertilization
-Restoration of the diploid number of chromosomes
--Half from the mother; half from the father
-Determination of sex
--X carrying spermatozoon produces female embryo
--Y carrying spermatozoon produces male embryo
-Initiation of cleavage (cell division)
-After reaching the two-cell stage, the zygote undergoes a series of __
--Cells become __ with each cleavage division
--Cells are called __
--Loose cluster of cells through the __
- mitotic divisions
-- smaller
-- blastomeres
-- 8-cell stage
-At the 8-cell stage the cells undergo __
--Blastomeres maximize contact with each other forming __
--Separates inner cells, which communicate extensively by __, from outer cells
-About 3 days after fertilization, the compacted cells divide again forming the __
--Inner cells form the __
---Gives rise to the tissues of the __
--Surrounding cells form the __
---Forms the __
- compaction
-- tight junctions
-- gap junctions
- 16 cell morulla
-- inner cell mass
--- embryo proper
-- outer cell mass
--- trophoblast
-About the time the __ enters the uterine cavity, fluid begins to penetrate the __ and enter the intercellular spaces of the inner cell mass
--The spaces become confluent forming a single cavity, the __
- morula; zona pellucida
-- blastocele
-With formation of the blastocele, the embryo is now called a __
--Inner cell mass now called the __ is at one pole
--Outer cell mass, or __, forms the wall of the __
--The __ has disappeared
---Allows __ to begin
- blastocyst
-- embryoblast
-- trophoblast; blastocyst
-- zona pellucida
--- implantation
-__ cells over the embryoblast pole begin to penetrate the uterine epithelial lining cells on about the __
--The embryo is captured on the mucosa by __ on the trophoblastic cells
--__ expressed by the trophoblast interact with laminin and fibronectin extracellular matrix molecules promoting __ and __
- trophoblastic; 6th day
-- selectins
-- integrins; attachment; invasion
-The inner cells of the __ form the inner cell mass. The inner cell mass undergoes a name change and becomes the __.
-The outer cell mass forms the __, which contributes to __.
-Note: Sometimes the terms embryo and __ are used interchangeably.
- morula; embryoblast
- trophoblast; placenta formation
- blastocyst
-The second week is often referred to as the “__.”
-The trophoblast differentiates into the __ and the __.
-The embryoblast differentiates into the __ and the __.
-The extraembryonic mesoderm splits into two layers: the __ and __.
-Two cavities form: the __ cavity and the __ cavity.
-Note: Embryos of the same fertilization age do not necessarily __ at the same rate.
- week of twos
- cytotrophoblast; synctiotrophoblast
- epiblast; hypoblast
- splanchnopleure; somatopleure
- amniotic; yolk sac
- develop
-The __ becomes partially embedded in the __.
-There are two layers of the trophoblast:
1.__ – has an __ cellular layer composed of mononuclear cells (cells containing only one nucleus).
2. __ – the __ cellular layer with multinucleate cells (cells with multiple nuclei); there are no distinct cellular boundaries
- trophoblast; endometrium
1. cytotrophoblast; inner
2. syncytiotrophoblast; outer
- __ occurs in the cytotrophoblast, which acts as a __.
-Cells from the cytotrophoblast migrate into the __ and fuse together, forming the __ seen in the syncytiotrophoblast.
-The embryoblast/inner cell mass differentiates into two layers:
1.__ – a layer of __ cells near the blastocyst cavity.
2.__ – a layer of __ cells near the amniotic cavity.
-Both of these germ layers form a flat disc known as the __.
- mitosis; cellular reservoir
- syncytiotrophoblast; multinucleate
1. hypoblast; cuboidal
2. epiblast; high columnar
- bilaminar germ disc
Day 8
-The __ begins as a small cavity in the epiblast.
-__ are epiblast cells that are adjacent to the cytotrophoblast.
-__ line the amniotic cavity.
-The __ adjacent to the implantation site is edematous and highly __.
-The large, tortuous glands secrete lots of __ and __.
- amniotic cavity
- amnioblasts
- amnioblasts
- endometrium; vascular
- glycogen; mucus
-The blastocyst is more deeply embedded in the __.
-The penetration defect in the surface epithelium of the endometrium is closed by a structure called the __
-The __ begins to differentiate near the embryonic pole, where vacuoles or spaces appear in the syncytium.
-When these vacuoles fuse, they form larger spaces called __.
-This phase of trophoblast development is called the __.
- endometrium
- fibrin coagulum
- trophoblast
- lacunae
- lacunar stage
-At the __ (the pole opposite the embryonic pole), flattened cells that originate from the hypoblast form a thin membrane called the __ membrane that lines the inner surface of the __.
-This membrane, together with the hypoblast, forms the lining of the __, or the __.
- abembryonic pole; exocoelomic membrane; cytotrophoblast
- exocoelomic cavity; primitive yolk sac
DAYS 11 and 12
-By this time, the __ is almost completely embedded in the endometrium.
-The defect in the __ is almost completely covered.
-The blastocyst causes a slight protrusion into the __.
-The trophoblast is characterized by __ spaces in the syncytium that form an intercommunicating network.
-This network is particularly evident at the __.
-At the abembryonic pole, the trophoblast still consists mainly of __.
- blastocyst
- endometrium
- uterine lumen
- lacunar spaces
- embryonic pole
- cytotrophoblastic cells
DAYS 11 and 12
-Cells of the __ penetrate deeper into the endometrium and erode the lining of the maternal capillaries.
-The __ are congested and dilated; they are called __.
-The __ become continuous with the sinusoids, and maternal blood enters the lacunar system.
-As the __ continues to erode more and more sinusoids, maternal blood begins to flow through the __ system.
-The __* is then established.
- capillaries; sinusoids
- lacunae
- trophoblast; trophoblastic
- Uteroplacental circulation
days 11 and 12
-Meanwhile…cells derived from the yolk sac form a loose connective tissue between the inner surface of the cytotrophoblast and the outer surface of the exocoelomic cavity called the __.
-The __(previous) eventually fills all of the space between the __ externally and the __ internally.
-Large cavities develop in the extraembryonic mesoderm, and when these cavities join together, they form a new space known as the __, or the __
-This space surrounds the primitive __ and __ except where the bilaminar disc is connected to the trophoblast by the connecting stalk.
-extraembryonic mesoderm
- extraembryonic mesoderm; trophoblast; exocoelomic membrane
- extraembryonic coelom; chorionic cavity
- yolk sac; amniotic cavity
DAYS 11 and 12
-The extraembryonic mesoderm lining the cytotrophoblast and amnion is called the __.
-The lining covering the yolk sac is known as the __.
-Growth of the __ is slow compared to that of the trophoblast, so the disc remains small.
-Around the site of implantation, cells of the endometrium become polyhedral in shape, become filled with __ and __.
-__ fills the extracellular spaces.
-These changes, known as the __, occur in the area immediately surrounding the implantation site but soon occur throughout the endometrium.
-The extraembryonic mesoderm lining the cytotrophoblast and amnion is called the extraembryonic somatopleuric (parietal) mesoderm.
-The lining covering the yolk sac is known as the extraembryonic splanchnopleuric (visceral) mesoderm.
-Growth of the bilaminar disc is slow compared to that of the trophoblast, so the disc remains small.
-Around the site of implantation, cells of the endometrium become polyhedral in shape, become filled with glycogen and lipids.
-Fluid fills the extracellular spaces.
-These changes, known as the decidua reaction, occur in the area immediately surrounding the implantation site but soon occur throughout the endometrium.
day 13
-The defect in the __ usually has healed by this time.
-However, some bleeding may occur at the implantation site due to increased blood flow into the __.
-Since this happens around day __ of the menstrual cycle, it is often confused with normal menstrual bleeding.
-This may cause __ in determining the expected __
- endometrium
- lacunar spaces
- 28; normal
- inaccuracy; date of delivery
DAY 13
-__ form in the trophoblast.
-Cells of the __ proliferate and penetrate into the __.
-Cellular columns surrounded by syncytium form structures called __*.
- villous structures
- cytotrophoblast; syncytiotrophoblast
- primary villi
day 13
-The __ produces additional cells that migrate along the inside of the exocoelomic membrane.
-These cells proliferate and gradually form a new cavity within the __.
-This new cavity is known as the __ or
-This new yolk sac is much __ than the __, or __.
-During its formation, large portions of the __ are pinched off.
-These pinched off portions are called __, which are often found in the extraembryonic coelom or chorionic cavity
-The hypoblast produces additional cells that migrate along the inside of the exocoelomic membrane.
-These cells proliferate and gradually form a new cavity within the exocoelomic cavity.
-This new cavity is known as the secondary yolk sac or definitive yolk sac.
-This new yolk sac is much smaller than the original exocoelomic cavity, or primitive yolk sac.
-During its formation, large portions of the exocoelomic cavity are pinched off.
-These pinched off portions are called exocoelomic cysts, which are often found in the extraembryonic coelom or chorionic cavity
day 13
-The extraembryonic coelom expands and forms a large cavity, the __.
-The extraembryonic mesoderm lining the inside of the cytotrophoblast is called the __.
-The only place where extraembryonic mesoderm crosses the chorionic cavity is in the __.
-When the blood vessels develop, the connecting stalk becomes the __
- chorionic cavity
- chorionic plate
- connecting stalk*
- umbilical cord
is the conceptus an invader?
-Because 50% of the implanting embryo’s genome is derived from the father, it is a foreign body that should be rejected by the mother.
-Recent evidence suggests that a combination of factors protects the conceptus, including production of __ and proteins, as well as the expression of an unusual __ class __ molecule (HLA-G) that blocks the recognition of the conceptus as foreign tissue.
-If the mother suffers from an __, such as systemic lupus erythematosus, antibodies generated by the disease may attack the conceptus and reject it.
-Patients with __ have poor reproductive outcomes and histories of spontaneous abortions
- immunosuppressive cytokines; MHC; IB molecule
- autoimmune disease
- autoimmune disease
Abnormal implantation
-Abnormal implantation sites occur even within the uterus.
-Normally, the __ implants along the anterior or posterior uterine wall.
-Occasionally, the blastocyst implants close to the __ (opening) of the cervix, so that later in development, the placenta crosses the opening.
-This condition, which is called __, causes severe, even life-threatening bleeding in the second part of pregnancy and during delivery.
- blastocyst
- internal os
- placenta previa
-Implantation can take place outside the uterus, resulting in an __ or __.
-Ectopic pregnancies can occur at any place in the abdominal cavity, ovary, or uterine tube.
-However, 95% of ectopic pregnancies occur in the __, mostly in the __.
- extrauterine; ectopic pregnancy
- uterine tube***; ampulla***
-In the __, the blastocyst most frequently attaches itself to the peritoneal lining of the __ or the __.
-Sometimes, the blastocyst develops within the ovary causing a __
-In most ectopic pregnancies, the embryo dies around the __ of gestation, causing severe bleeding and abdominal pain in the mother.
- abdominal cavity; rectouterine cavity; pouch of douglas
- primary ovarian pregnancy
- second month
abnormal blastocysts
-It is likely that most __ would not produce any signs of pregnancy.
-This is because the trophoblast was so inferior that the __ could not have persisted.
-These embryos probably would have been aborted with the next __, so pregnancy would not have been detected
- abnormal blastocysts
- corpus luteum
- menstrual cycle
-In some cases, some abnormal blastocysts will have trophoblastic development and formation of placental tissues.
-This condition is called a __.
-Moles secrete high levels of __ and may produce benign or malignant __ (invasive mole, choriocarcinoma).
- hydatidiform mole
- hCG; tumors
-Genetic analysis of hydatidiform moles reveals that although male and female pronuclei may be genetically equivalent, they may be different functionally.
-This evidence comes from the fact that while cells of the moles are diploid, their entire genome is __.
-So, most moles arise from the fertilization of an oocyte lacking a nucleus, followed by duplication of the male chromosomes to restore the diploid number.
-These results also suggest that __ regulate most of the development of the __, since in moles this tissue differentiates even in the absence of a female pronucleus.
- paternal
- paternal genes; trophoblast
-__ is the process that establishes all three germ layers: __, __, and __
-Gastrulation begins with the formation of the __ on the surface of the __.
-The cephalic end of the streak, the __, consists of a slightly elevated area surrounding the __.
-Cells of the __ migrate toward the primitive streak.
-When they arrive, these cells become __, detach from the epiblast, and slip beneath it.
-The inward movement of the cells is called __.
-Gastrulation is the process that establishes all three germ layers: ectoderm, mesoderm, and endoderm.
-Gastrulation begins with the formation of the primitive streak on the surface of the epiblast.
-The cephalic end of the streak, the primitive node, consists of a slightly elevated area surrounding the small primitive pit.
-Cells of the epiblast migrate toward the primitive streak.
-When they arrive, these cells become flask-shaped, detach from the epiblast, and slip beneath it.
-The inward movement of the cells is called invagination.
-Cell migration and specification are controlled by __, which is synthesized by __.
-__(previous) down regulates __, a protein that normally binds __ cells together.
-FGF8 then controls cell specification into mesoderm by regulating __
- fibroblast growth factor 8 (FGF8); streak cells
- fgf8; E-cadherin; epiblast
- mesoderm; brachyury (T) expression
-Once the cells have invaginated, some of these cells displace the hypoblast, creating the __, and others come to lie between the epiblast and newly created endoderm to form __.
-Cells remaining in the epiblast then form __.
-So, the epiblast is the source of all of the germ layers.
-Cells in the germ layers will give rise to all of the tissues and organs in the embryo.
- embryonic endoderm; mesoderm
- ectoderm
- epiblast
- germ layers
-As more cells move between the __ and __ layers, they begin to spread laterally and cranially.
-Gradually they migrate beyond the margin of the disc and establish contact with the __ that covers the __ and __.
-In the cephalic direction, they pass on each side of the __
- epiblast; hypoblast
- extraembryonic mesoderm; yolk sac; amnion
- prechordal plate
-The __ itself forms between the tip of the __ and the __ membrane and is derived from some of the first cells that migrate through the node in the cephalic direction.
-Later, the __(previous) will be important for the induction of the __.
-The __ at the cranial end of the disc consists of a small region of tightly adherent __ and __ cells that represents the future opening of the __.

-Note: The new terminology is __ membrane, replacing buccopharyngeal membrane.
- prechordal plate; notochord; buccopharyngeal membrane
- prechordal plate; forebrain
- buccopharyngeal membrane; ectoderm; endoderm; oral cavity
- oropharyngeal
formation of the notochord
-__ invaginating in the primitive pit move forward cranially until they reach the __.
-Prenotochordal cells become inserted into the __, so that for a short time, the midline of the embryo consists of two cell layers that form the __
-As the hypoblast is replaced by __ cells that move in at the streak, cells of the notochordal plate proliferate and detach from the endoderm.
-They then form a solid cord of cells, the definitive __.
-The notochord underlies the __ and serves as the basis for the __.
- prenotochordal cells; prechordal plate
- hypoblast; notochordal plate
- endoderm
- notochord
- neural tube; axial skeleton
-The _ end of the __ forms first, while the __ regions are added as the primitive streak assumes a more caudal position.
-The notochord and prenotochordal cells extend cranially to the __, an area just caudal to the __ and caudal to the __.
-At the point where the pit forms an indentation in the epiblast, the __ temporarily connects the __ and __ cavities.
- cranial end; notochord; caudal
- prechordal plate; buccopharyngeal membrane; primitive pit
- neurenteric canal; amniotic; yolk sac
formation of the notochord
-The __ is formed at the caudal end of the embryonic disc.
-The __(previous_), which is similar to the buccopharyngeal membrane, consists of tightly adherent __ and __ cells.
-When the cloacal membrane appears, the posterior wall of the __ forms a small diverticulum that extends into the __.
-The diverticulum is called the __ or __.
-The __ remains rudimentary in humans and can be involved in abnormalities of bladder development.
- cloacal membrane
- cloacal membrane; ectoderm; endoderm
- yolk sac; connecting stalk
- allantoenteric diverticulum; allantois
- allantois
-Establishment of body axes, anteroposterior, dorsoventral, and left-right, takes place before and during __.
-The anteroposterior axis is signaled by cells at the anterior (cranial) margin of the __.
-This area, the __ expresses genes essential for head formation, including three transcription factors and the secreted factors __ and __.
-These genes and growth factors establish the __ of the embryo before gastrulation.
-__, a growth factor, initiates the formation of and maintains the __.
-Once the streak is formed, a number of __ regulate formation of dorsal and ventral mesoderm and head and tail structures
- gastrulation
- embryonic disc
- anterior visceral endoderm (AVE); cerberus; lefty
- cranial end
- nodal; primitive streak
- genes
establishment of body axis
-__ is secreted throughout the embryonic disc.
-__ and __ cause mesoderm to be ventralized, which contributes to the formation of __, __, and body wall __.
-All mesoderm would be ventralized if BMP4 were not blocked by other genes expressed by the node.
-So, the node is considered to be the organizer.
-Hans Spemann first designated the node as the organizer.
-bone morphogenetic protein 4 (BMP4)
- BMP4; FGF; kidneys; blood; mesoderm
- BMP4
- node; organizer
establishment of body axes
-So, __ (activated by the transcription factor __), __ and __ antagonize the activity of __.
-As a result, __ is dorsalized into __, __, and __.
-Later, these three genes are expressed in the __, and are important in __ in the cranial region.
- chordin; (goosecoid); noggin; follistatin; BMP4
- cranial mesoderm; notochord; somites; somitomeres
- notochord; neural induction
establishment of body axes
-___ maintains the node and later induces regional specificity in the forebrain and midbrain areas.
-Without __, embryos fail to gastrulate properly and lack forebrain and midbrain structures
- HNF-3Beta
- HNF-3beta
establishment of body axes
-Note: __ activates inhibitors of BMP4 and contributes to the regulation of __.
-Over- or under expression of this gene results in __ of the head region.
-__ and some types of conjoined twins can result due to over expression of __.
- goosecoid; head development
- severe malformations
- head duplications; goosecoid
establishment of body axes
-Regulation of __ formation in the middle and caudal regions of the embryo is controlled by the __ gene expressed in the __, __ cells, and __.
-__ encodes a transcription factor which causes mesoderm formation in the middle and caudal regions.
-The absence of Brachyury results in shortening of the __ (__).
-The degree of shortening depends on the time at which the protein becomes deficient.
- dorsal mesoderm; brachyury; node; notochord precursor; notochord
- brachyury
- embyronic axis (caudal dysgenesis)
-Gastrulation may be interrupted by __ or __.
-In caudal __ or __, insufficient mesoderm is formed in the caudalmost region of the embryo.
-Because this mesoderm contributes to the formation of the lower limbs, urogenital system (intermediate mesoderm), and lumbosacral vertebrae, abnormalities in these structures are seen.
- genetic abnormalities; toxic insults
- caudal dysgenesis; sirenomelia
-_:Affected individuals exhibit a variety of defects, including hypoplasia and fusion of the lower limbs, vertebral abnormalities, renal agenesis, imperforate anus, and anomalies of the genital organs.
-The condition is associated with __, __, and the absence of __.
-Sirenomelia is almost always __, with __ of babies stillborn and approximately __ dying within a few minutes to a few days.
- caudal dysgenesis (sirenomelia)
- maternal diabetes; twinning; brachyury
- fatal; 50%; 50%
establishment of body axes
-__ is established early in development and is orchestrated by a cascade of genes.
-When the primitive streak appears, __ is secreted by cells in the __ and __, which induces expression of __, but only on the __ side of the embryo.
-Later, after the establishment of the neural plate, __ maintains __ expression in the lateral plate mesoderm as well as __.
-Both __ and __ upregulate PITX2.
-PITX2 is a homeobox-containing transcription factor responsible for establishing __.
-If the gene is expressed on the right side, laterality defects such as __ and __ result
- left-right sidedness
- FGF8; node; primitive streak; nodel; left
- FGF8; nodal; lefty-2
- nodal; lefty-2
- left sidedness
- situs inversus; dextrocardia
establishment of body axes
-Lefty-1 is expressed on the __ of the __ of the __ and may act as a barrier to prevent left-sided signals from crossing over.
-__ may also act as a repressor for left-sided gene expression on the right side.
-The __ gene, that encodes a transcription factor secreted by the notochord, is also essential for the expression of __, __ and __.
- left side; floor plate; neural tube
- SHH (sonic hedge hog)
- brachyury T; nodal; lefty-1; lefty-2
establishment of body axes
-The neurotransmitter __ plays a crucial role in the signaling cascade that establishes laterality.
-5HT is concentrated on the left side, probably because it is broken down by the enzyme __ on the right and upstream from FGF8 signaling.
-Alterations in 5HT signaling result in __, __, and other __.
- serotonin (5ht)
- monoamine oxidase
- situs inversus; dextrocardia; heart defects
establishment of body axes
-Genes regulating right-sided development are not as well defined as those on the left, although expression of the transcription factor ___ is restricted to the right lateral plate mesoderm and probably regulates the effector genes responsible for establishing the right side.
-It is still not understood why the cascade is initiated on the left, but __ on cells in the __ beat to create a gradient established by __ and small __ transport.
- Snail
- cilia; node; gap junctions; ion
establishment of fate map
-Cells of the epiblast that enter through the cranial region of the node become __.
-Cells migrating at the lateral edges of the node and from the cranial end of the streak become __.
-Cells migrating through the midstreak region become __.
-Those cells migrating through the more caudal part of the streak from __
-Cells migrating through the caudalmost part of the streak contribute to __ (the other source of this type of mesoderm is the primitive yolk sac (hypoblast).
- notochord
- paraxial mesoderm
- intermediate mesoderm
- lateral plate mesoderm
- extraembryonic mesodrm
growth of the embryonic disc
-The __ is initially flat and almost round, but gradually becomes elongated, with a broad __ end and a narrow __ end.
-Expansion of the disc occurs mainly in the __ region, while the region of the __ remains about the same size.
-Growth and elongation of the cephalic part of the disc are caused by a continuous migration of cells from the __ region in a cephalic direction.
-Invagination of surface cells in the __ and their subsequent migration forward and laterally continues until the end of the __.
-At that time, the primitive streak shows signs of __, __, and soon __
- embryonic disc; cephalic; caudal
- cephalic; primitive streak
- primitive streak
- primitive streak; fourth week
- regression;rapidly shrinks; disappears
growth of the embryonic disc
-It is interesting that the __ at the __ end of the embryo continues to supply new cells until the end of the __.
-In the cephalic part of the embryo, the germ layers begin their differentiation by the middle of the __, whereas in the caudal part, differentiation begins by the end of the __.
-So, gastrulation continues in __ segments, while __ structures are differentiating, causing the embryo to develop __
-primitive streak; caudal; fourth week
- third week; fourth week
- caudal; cranial; cephalocaudally
further development of the trophoblast
-By the start of the third week, the trophoblast has __: cytotrophoblast core covered by a __.
-During further development, __ cells invade the core of the primary villi and grow toward the __.
-This newly formed structure is known as a __.
- primary villi; synctial layer
- mesodermal; decidua
- secondary villus
further development of the trophoblast
-By the end of the third week, __ in the core begin to differentiate into __ and __, forming the __ system.
-The villus is now called a __ or definitive villus.
-Capillaries in __(previous) make contact with __ developing in __ of the chorionic plate and the connecting stalk.
-These vessels, in turn, establish contact with the __, connecting the placenta and the embryo.
-So, when the heart begins to beat in the __, the __ system is ready to supply the embryo with nutrients and oxygen.
- mesodermal cells; blood vessels; blood cells; villous capillary
- tertiary villus
- tertiary villi; capillaries; mesoderm
- intraembryonic circulatory system
- fourth week; villus
clinical correlate
-The beginning of the third week of development is a highly sensitive stage for __.
-__ are drugs or other agents that cause abnormal prenatal development.
-At this time, __ can be made for various organ systems, such as those for the eyes and brain.
-These cell populations may be damaged by __.
-For example, high doses of __ at this stage kill cells in the __ of the germ disc, producing a deficiency of the midline in __ structures.
-This results in a condition known as __.
-In severe cases, the __ are fused and the __ is located above the eye.
-In mild cases, the only indication is a single __.
- teratogenic insulte
- teratogens
- fate maps
- teratogens
- alcohol; anterior midline; craniofacial
- holoprosencephaly
- eyes; nose
- incisor tooth
clinical correlate
-__ is a condition in which the viscera (organs) of the thorax and abdomen are transposed or reversed.
It has been estimated that situs inversus occurs once in __ to __ births.
-Despite this reversal, other structural abnormalities occur only slightly more __.
-Approximately 20% of patients with complete situs inversus also have __ problems including chronic __ because of abnormal __ (__).
-__ are normally present on the __ surface of the __ and may be involved in left-right patterning during gastrulation.
- situs inversus
- 6000; 8000
- frequently
- respiratory; sinusitis; cilia (kartagener's syndrome)
- cilia; ventral; primitive
clinical correlate
-Sometimes, remnants of the __ persist in the sacrococcygeal region.
-The clusters of these pluripotent cells proliferate and form tumors known as __.
-These tumors commonly contain tissues from all __.
-This is the most common tumor in __, occurring with a frequency of 1 in 37,000.
-These tumors may also arise from __ that fail to migrate to the __.
- primitive streak
- sarcococcygeal tumors
- three germ layers
- newborns
- primordial germ cells; gonadal ridge
the embryonic period
-The embryonic period is also known as the period of __.
-This is the time when each of the __ gives rise to specific tissues and organs.
-By the end of the embryonic period, the main __ have been established.
-The main features of the external body are recognizable by the end of the second month.
- organogenesis
- three germ layers (ectoderm, mesoderm, and endoderm)
- organ systems
- second month
-At the beginning of the third week of development, the __ has the shape of a disc that is broader in the __ region than in the __ region.
-The appearance of the notochord and prechordal mesoderm induces the overlying __ to thicken and form the __.
-Cells of the plate make up the __, and their induction initiates the process of __
- ectodermal germ layer; cephalic; caudal
- ectoderm; neural plate
- neuroectoderm; neurulation
-Once induction has occurred, the elongated __ gradually expands toward the __.
-By the end of the third week, the lateral edges of the __ become more elevated to form __, and the depressed midregion forms the __.
-Gradually the neural folds grow toward each other in the midline, where they __.
-Fusion begins in the __ region and proceeds __ and __.
-This fusion results in the formation of the __.
-Until fusion is complete, the __ and __ ends of the neural tube remain open and communicate with the amniotic cavity by way of the __ and __
- neural plate; primitive streak
- neural plate; neural folds; neural groove
- fuse
- cervical; cranially; caudally
- neural tube
- cephalic; caudal; cranial; caudal neurophores
-Closure of the cranial neuropore occurs at approximately __*, and closure of the caudal neuropore occurs at day ___*.
-__ is then complete and the central nervous system is represented by a closed tubular structure with a narrow caudal portion, which forms the spinal cord, and a much broader cephalic portion characterized by a number of dilations called the __.
- day 25; day 27
- neurulation; brain vesicles
-As the __ elevate and fuse, cells at the lateral border or crest of the __ begin to dissociate from their neighbors.
-This cell population, the __, will undergo an __-to-__ transition as it leaves the neuroectoderm by active migration and displacement to enter the underlying mesoderm.
-Note: Mesoderm refers to cells derived from the __ and ___. __ refers to loosely organized embryonic connective tissue regardless of origin**
- neural folds; neuroectoderm
- neural crest; epithelial; mesenchymal
- epiblast; extraembryonic tissues; mesenchyme
neural crest cells
- Intermediate levels of __ induce neural crest formation.
-__ (previous) also regulate the migration, proliferation, and differentiation of __
- BMPs; neural crest cells
clinical correlate: neural tube defects
-Neural tube defects result when the neural tube fails to __.
-If the neural tube fails to close in the cranial region, the defect is called __.
-If the neural tube fails to close anywhere from the cervical region caudally, the defect is called __.
-Neural tube defects can be prevented if women take __ of ___ daily, beginning 3 months prior to conception.
- close
- anencephaly
- spina bifida
- 400 micrograms; folic acid
ectodermal derivatives
-The ectodermal germ layer gives rise to organs and structures that maintain contact with the outside world:
-It also gives rise to __ glands, the __ glands, the __ gland, and the __
- CNS; peripheral nervous system; sensory epithelium of the ear, nose, and eye; epidermis including hair and nails
- subcutaneous; mammary; pituitary; enamel of the teeth
derivatives of the mesoderm germ layer
-Initially, cells of the mesoderm form a thin sheet on either side of the midline.
-Around the 17th day, cells close to the midline proliferate and form a thickened plate of tissue known as __.
-More laterally, the mesoderm layer remains thin and is known as the __.
-The lateral plate divides into two layers:
--__ or __
--__ or __
- paraxial mesoderm
- lateral plate
-- somatic or parietal mesoderm
-- splanchnic or visceral mesoderm
derivatives of the mesoderm germ layer
-Somatic/parietal mesoderm is a layer that is continuous with mesoderm covering the __.
-Splanchnic/visceral mesoderm is a layer that is continuous with mesoderm covering the __.
-Together, these layers line a newly formed cavity, the __, which is continuous with the extraembryonic cavity on each side of the embryo.
-__ connects paraxial and lateral plate mesoderm.
- amnion
- yolk sac
- intraembryonic cavity
- intermediate mesoderm
derivatives of the mesoderm germ layer
-By the beginning of the third week, __ begins to be organized into segments.
-These segments, known as __, first appear in the cephalic region of the embryo.
-Their formation proceeds in a __ direction.
-Somitomeres further organize into __.
-__(previous) ultimately differentiate into __ and __, __, and __.
-Since somites appear in with a specified periodicity, the age of an embryo can be accurately determined by __ (see Table 6.2, p. 77)
- paraxial mesoderm
- somitomeres
- cephalocaudal
- somites
-somites; vertebrae; ribs; muscles; dermis
- counting somites
Neural crest cells form the following:
-Connective tissue and bones of the face and skull
-Cranial nerve ganglia
-C cells of the thyroid gland
-Conotruncal septum of the heart
-Dermis in the face and neck
-Dorsal root ganglia
-Sympathetic chain ganglia and preaortic ganglia
-Parasympathetic ganglia of the GI tract
-Adrenal medulla
-Schwann cells
-Glial cells
-Meninges of the forebrain
-Smooth muscle cells of blood vessels in face and forebrain
derivatives of the mesoderm germ layer
-__ splits into parietal and visceral layers, which line the __ cavity and surround the __, respectively.
-Mesoderm from the parietal layer, together with overlying __, will form the __ and __.
-The visceral layer and embryonic endoderm will form the wall of the __.
-Mesodermal cells of the __ layer surrounding the intraembryonic cavity will form thin membranes, the __ membranes, or __ membranes, which line the pleural, pericardial, and peritoneal cavities.
-Mesodermal cells of the __ layer will form a thin serous membrane around each organ.
- lateral plate mesoderm; intraembryonic cavity; organs
- ectoderm; lateral; ventral body wall
- gut
- parietal; mesothelial membranes; serous membranes
- visceral
derivatives of mesoderm germ layer
-Blood vessels form in two ways:
--__, where vessels arise from blood islands.
--__, where vessels arise by sprouting from existing vessels.
-The first blood islands appear in mesoderm surrounding the wall of the yolk sac at 3 weeks of development and slightly later in lateral plate mesoderm.
-These islands arise from mesoderm cells that are induced to form __, a common precursor for vessel and blood cell formation.
-__(previous) are induced by __, which is secreted by surrounding mesoderm cells.
-- vasculogenesis
-- angiogenesis
- hemangioblasts
- hemangioblasts; vascular endothelial growth factor (VEGF)
derivatives of endoderm germ layer
-The __ is the main organ system that is derived from the endodermal germ layer.
-This germ layer covers the ventral surface of the __ and forms the root of the __.
-With the development and growth of the brain vesicles, the embryonic disc begins to bulge into the __ cavity and to fold cephalocaudally.
-This folding is most pronounced in the __ and __ regions, where the __ fold and __ fold are formed.
- gastrointestinal tract
- embryo; yolk sac
- amniotic cavity
- head; tail; head; tail
derivative of the endodermal germ layer
-As a result of the cephalocaudal folding, a continuously larger portion of the endoderm-lined cavity is incorporated into the body of the embryo.
-In the anterior part, the endoderm forms the __.
-In the tail region, the endoderm forms the __.
-The part between the foregut and hindgut is the __.
--The __(previous) temporarily communicates with the __ by way of a broad stalk, the __.
- foregut
- hindgut
- midgut
-- midgut; yolk sac; vitelline duct
derivatives of the endoderm germ layer
-At its cephalic end, the foregut is temporarily bounded by an ectodermal-endodermal membrane called the __.
-In the fourth week, the __ (previous) ruptures, establishing an open connection between the __ and the __.
-The hindgut also terminates temporarily at an ectodermal-endodermal membrane, the __, which breaks down in the seventh week to create the opening for the anus.
- buccopharyngeal membrane
- buccopharyngeal membrane; amniotic cavity; primitive gut
- clocal membrane
derivatives of the endodermal germ layer:
-The endodermal germ layer initially forms the epithelial lining of the primitive gut and the intraembryonic portions of the allantois and vitelline duct.
-Later, it gives rise to:
--The epithelial lining of the respiratory tract.
--The parenchyma of the thyroid, parathyroids, liver and pancreas.
-The reticular stroma of the tonsils and thymus.
-The epithelial lining of the urinary bladder and urethra.
-The epithelial lining of the tympanic cavity and auditory tube.
fetal development
- __: Beginning of ninth week to birth
- Maturation of __ and __
-Growth of the body
--Growth in length predominates early
--Increase in __ last 2 ½ months
-Length of gestation
-__ days or __ weeks from last normal menstrual period
-__ days or __ weeks from fertilization
- fetal period
- organs and tissues
-- weight
-- 280; 40 weeks
-- 266; 38
fetal development
- slowdown in __ relative to rest of body
- head growth
third month
-__ becomes more human looking
--__ move to ventral aspect of face
--__ move close to their final position
-__ reach relative length in relation to body length
--__ remains a little behind
-__ appear in skull and long bones
-__ develop to point where sex can be determined by external examination
-__ withdraw into abdomen from umbilical cord
-__ activity is present
- face
-- eyes
-- ears
- limbs
-- lower limb
- primary ossification centers
- external genitalia
- intestinal loops
- muscular
fourth and fifth
- __ lengthens rapidly
--__ length is about 15 cm
-__ increases little: Still <500 g
-Covered with __
--Eyebrows and head hair present
-During the __, the mother can feel fetal movement
- fetus
-- crown-rump
- weight
- fine hair (lanugo hair)
- fifth month
sixth and seventh month
- Skin is __ and __
--Lack of underlying __
-Fetus at the edge of __
--__ and __ are still too immature
--By the end of 7th month
---Length 25 cm, weight 1100 g
---Now has high chance of survival
- reddish; wrinkled
-- connective tissue
- viability
-- respiratory; cns
eights and ninth month
-__ increases
--Deposition of __
--Rounder contours
-At end of gestation
--Skin covered by a white fatty substance from the secretory products of __, called __
--__ has the largest circumference of all body parts
--Normal fetus: 3000-3400 g, CHL 50 cm, CRL 36 cm
-- subcutaneous fat
-- sebaceous glands; vernix caseosa
-- head
time of birth
-Most accurate: __ days after fertilization
--Usually difficult to determine
-Fairly accurate: __ days from first day of last normal menstrual period
--Inaccuracies from irregular periods or erosive activity of __ blastocyst causing bleeding
-Most fetuses are born within 10-14 days of calculated date
--If born much earlier, they are categorized as __
--If born later, __
- 266
- 280
-- implanting
-- premature
-- postmature
Time of birth
-__ is used commonly to help manage pregnancies
--Measurements made by ultrasound are highly accurate in determining fetal age
--Accurate to within 1-2 days prior to 16 weeks
--After 16 weeks, a composite of several measurements
---Biparietal diameter, head circumference, abdominal circumference, femur length
- ultrasound
fetal membranes and placenta
-Demand for nutritional and other factors grows as the __ grows
-__ changes to meet these requirements
-Increased __ production also changes the configuration of the fetal membranes
- fetus
- placenta
- amniotic fluid
-Numerous small extensions grow out from the __ forming the __ that extend into the intervillous spaces
--Initially primitive in configuration
--Reconfigure so that fetal and maternal circulation are separated by only the __ and the __
- stem villi; free villi
-- endothelial wall; syncytium
-Initially, villi cover the entire surface of the __
-As pregnancy advances, the villi continue to grow and expand on the __ becoming the __
-Villi on the __ degenerate (__)
- chorion
- embryonic pole;chorion frondosum
- abembryonic pole; (chorion leave)
-These changes are also reflected in the __
--The __ is adjacent to the chorion frondosum and consists of large cells with abundant __ and __
--The __ over the abembryonic pole stretches and degenerates as pregnancy progresses
---The __ leave eventually contacts the __ and fuses with it obliterating the uterine cavity
- decidua
-- decidua basalis; lipid; glycogen
-- decidua capsularis
--- chorion; uterine wall (decidua parietalis)
-The only part of the chorion participating in exchange between maternal and fetal circulation is the __
-Together the __ and the __ make up the placenta
-The __ also expands with continuation of pregnancy and eventually obliterates the __ with fusion of the amnion and chorion into the amniochorionic membrane
- chorion frondosum
- chorion frondosum; decidua basalis
- amniotic cavity; chorionic cavity
structure of placenta
-Formed by the beginning of the 4th month
Fetal part: __
Maternal part: __
Fetal side: ___
Maternal side: __
-4th and 5th month: __ form
--Projections of decidua into the intervillous spaces
--Don’t reach __
--Divides the placenta into __
-- chorion frondosum
-- decidua basalis
-- chorionic plate
-- decidual plate
- decidual septa
-- chorionic plate
-- cotyledons
- full term placenta
--15-25 cm diameter, 3 cm thick
--500-600 g
--15-20 __
--Umbilical cord attached near center
--Expelled from the uterus about __ after birth of child
-- cotyledons
-- 30 minutes
placental circulation
-__ supply the placenta
-Blood circulates through the __ bathing the villi then exits through __ back at the __
--__ contain about 150 ml of blood
--Replenished 3-4 times per minute
-Placental exchange occurs in those villi where __ are in close contact with the __ covering the villous
- 80-100 spiral arteries
- intervillous spaces; endometrial; decidual plate
-- intervillous spaces
- fetal capillaries; syncytium
function of placenta: exchange of gases
-Gases are exchanged by simple __
-Fetus extracts 20-30 ml of __ per minute
-Even short-term interruption of __ delivery is fatal to a fetus
-__ is critical to oxygen delivery
- diffusion
- oxygen
- oxygen
- placental blood flow
function of placenta
-Exchange of __ and __
--Amino acids, free fatty acids, carbohydrates, vitamins
-Transmission of maternal __
-- includes __ and __ immunity
- nutrients; electrolytes
- antibodies
-- IgG; passive immunity
function of placenta: hormone production
- hormones are synthesized in the __
- placental hormones include:
- synctiotrophoblast
- progesterone; estrogenic hormones, primarily estriol; human chorionic gonadotropin; somatomammotropin (formerly placental lactogen)
function of placenta: hormone production
-Hormones are synthesized in the __
--Can support the pregnancy without the __ by end of __ month
--Estrogenic hormones, predominately estriol
--__ growth and __ development
-Human chorionic gonadotropin
--Secreted in early pregnancy to support the __
-Somatomammotropin (formerly placental lactogen)
--Fetal priority for maternal __
--Makes mother __
--__ development and __ production
--__ hormone-like
-- corpus luteum; 4th
-- uterine; mammary gland
--corpus luteum
-- blood glucose
-- diabetogenic
-- breast; milk
-- growth
umbilical cord
-Primitive umbilical ring is the oval line of reflection between the __ and the __
- contains:
-- __: allantois, umbilical vessels
-- __: vitelline duct and vessels
--canal connecting the __ and __
- amnion; embryonic ectoderm
-- connecting stalk
-- yolk stalk
-- extraembryonic; intraembryonic cavities
umbilical cord
-As the amniotic cavity expands, the amnion begins to envelope the connecting stalk and yolk stalk forming the __
-Eventually, only the __ surrounded by __ (a type of mucous tissue) make the umbilical cord
- primitave umbilical cord
- umbilical vessels; wharton's jelly
amniotic fluid
-The amniotic cavity is filled with a clear, watery fluid derived primarily from __
--__ at 10 weeks
--__ ml at 20 weeks
--__ at 37 weeks
-During early months, the embryo is suspended by its __ in the amniotic fluid
- maternal blood
--800-1000 ml
- umbilical cord
amniotic fluid
- The fluid acts to:
--Absorb jolts
--Prevent adherence of the embryo to the __
--Allow fetal movements
-Replaced every __
-Starting in the 5th month, the fetus drinks about __ per day
-__ is added to the fluid
-- amnion
- 3 hours
- 400ml
- fetal urine
twins: dizygotic twins
-__ of twins are dizygotic, or fraternal
-7 to 11 per 1000 births, increases with __
-Ovulation and fertilization of two __
-Implant separately in __
-Each has its own __ and membranes
--Sometimes the __ or less commonly the placentas come into apposition and fuse
- 2/3
- maternal age
- oocytes
- uterus
- placenta
-- chorionic sacs
twins: monozygotic
-Develop from a single fertilized __
-3-4 per 1000 births
-Splitting of the __ at various stages of development
--May split as early as the __
---Two separate zygotes develop with their own __ and __
- oocyte
- zygote
-- two-cell stage
--- placentas; membranes
-Splitting may occur at the early __ stage
--__ splits within same blastocyst cavity
---Common __ and __; separate __ cavities (monochorionic, diamniotic)
-Separation at the __ stage, prior to appearance of the __
--Monochorionic, monoamniotic
- blastocyst
-- inner cell mass
--- placenta; chorion; amniotic
- bilaminar germ disc; primitive streak
__ are rare, 1 per 7600 pregnancies
twins: problems
-High __ and __
--12% of premature infants are twins
--Usually small at birth
--Prematurity and low birth weight result in increased mortality
-Vanishing twin
-Twin transfusion syndrome
-Obstetrical complications at delivery
- morbidity; mortality
Twins: conjoined (siamese) twins
- __ stage splitting
--Partial splitting of the __ and __
-Classified by nature and degree of union
- later
-- primitive node; streak
Parturition (birth)
-Factors initiating labor are not known
-“Retreat from maintenance of pregnancy”
--Withdrawal of supporting factors
--Active induction by stimulatory factors
-Labor is divided into three stages
--Stage 1: __ and __
--Stage 2: delivery of __
--Stage 3: delivery of __ and __
-- effacement; dilation of cervix
-- fetus
-- placenta; membranes
birth defects
-40-60% are of __
--Genetic factors: 15%
--Environmental factors: 10%
--Combination genetic and environmental: 20-25%
--Twinning: 0.5-1%
- unknown cause
birth defects
-Minor anomalies occur in 15% of newborns
--Small ears, pigmented spots, short palpebral fissures
M--ay be a clue to a major defects
---1 minor, 3% have major
--2 minors, 10%
--3 minors, 20%
--__ anomalies are especially important indicators
-- ear
types of abnormalities
-__: Complete or partial absence of a structure or alterations of its normal configuration
--Most originate during __ of gestation
-__: Morphological alteration of an already formed structure by a destructive process
-__: Mechanical forces mold a part of the fetus over time, Often musculoskeletal
- malformation
-- 3rd-8th week
- disruption
- deformation
types of abnormalities
-__: Group of anomalies occurring together that have a specific common cause
--Risk of __ is known
-__: Non-random appearance of two or more anomalies that occur more frequently than by chance alone, but the cause has not been determined
- syndrome
-- recurrence
- association
-__ factors can cause birth defects
--In the 1940s, it was discovered that __ infections early in pregnancy caused birth defects
--In 1961, limb defects were linked to use of __
--Many agents have now been identified as teratogens
- environmental
-- rubella
-- thalidomide
principles of teratology

-Susceptibility to teratogenesis depends on the genotype of the conceptus and the maternal genome
-Susceptibility to teratogens varies with developmental stage at the time of exposure
-Manifestations depend on dose and duration of exposure
-Teratogens have specific mechanisms to initiate pathogenesis
-Manifestations of abnormal development are death, malformation, growth retardation, and functional disorders
male mediated teratogenesis
-Exposure to chemicals and other agents can cause mutations in male germ cells
-Advanced paternal age is a factor for limb and neural tube defects, Down syndrome, and new autosomal mutations
-Paternal exposures have been linked to spontaneous abortion, low birth weight, and birth defects
-__:High frequency sound waves reflected from tissues to make images
--Transabdominal or transvaginal
--Fetal age and growth, structural abnormalities, amniotic fluid volume, blood and fluid flow, multiple gestations
--Neural tube defects, abdominal wall defects, heart defects, facial defects
- ultrasonography
maternal serum screening: Biochemical markers of fetal status
-__, __
--Neural tube defects have high levels
--Down syndrome has slightly lower levels
---Abdominal wall defects
-Hormone levels: hormone __
- afp; alpha-fetoprotein
- hormone hCG
- __:Needle inserted transabdominally and amniotic fluid is withdrawn
-->14 weeks gestation
--1% risk of fetal loss
-Fluid and cells for biochemical and genetic analysis:
- amniocentesis
- afp; karyotype; and enzyme/single gene levels
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