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Week 2
Embryology
111
Biology
Graduate
08/21/2008

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Term
Stem cells
Definition
cells that can self-renew in proper conditions and give rise to differentiated cells via asymmetrical division
Term
Ectoderm
Definition
germ layer that gives rise to skin and derivatives, CNS, nueral crest
Term
Mesoderm
Definition
germ layer that gives muscle, skeleton, kidneys, blood, connective tissue
Term
Endoderm
Definition
germ layer that gives epithelium of intestinal tract, thyroid, trachea, bronchi, lungs, liver, pancreas
Term
Gastrulation
Definition
morphogenetic movements of cells in embryo that create germ layers
Term
Epithelial-mesenchymal transition
Definition
point in development where tightly adhered epithelia can convert to loose, matrix encased mesenchymal cells or vice versa
Term
Cleavage
Definition
rapid divisions without cell growth
Term
Morula stage
Definition
transit through the fallopian tube, uterus in 3 days, uterine physiology changes with FSH, estrogen, LH, progesterone from Corpus Luteum, HCG
Term
Blastocyst stage
Definition
6th day the trophoblast, outer cells, attaches to endometrial epithelium, embryoblast, inner cells, separate in fluid filled cavity
Term
Where are embryonic stem cells derived from?
Definition
Inner cell mass, totipotent
Term
How are induced pluripotent cells derived?
Definition
Adult fibroblasts with introduced genes of 4 transciption factors to make it inner cell mass-like
Term
During the second week the bilaminar embryonic disc develops into 3 sets of twos, what are they?
Definition
Epiblast and hypoblast, synctiotrophoblast and cytotrophoblast, the amnion and primitive yolk sac
Term
Epiblast
Definition
from inner cell mas, columnar cells adjacent to the amniotic cavity, all adult cells derived from epiblast epithelium
Term
Hypoblast
Definition
from inner cell mass, cuboidal cells that adjacent to blastocyst cavity, aka primitive yolk sac
Term
Synctiotrophoblast
Definition
from trophoblast, outerlayer of multinucleated cells, secretes HCG, connects to sinusoids (maternal capillaries)
Term
Cytotropohblast
Definition
from trophoblast, inner layer of cells, supplies cells to synctio layer
Term
What happens during the third week of embryogenesis?
Definition
Gastrulation
Term
When is an invariant body pattern developed?
Definition
Gastrulation
Term
Elaborate on the primitive streak once it forms during gastrulation.
Definition
Epithelial-mesechymal transition, epiblast cells ingress inward to form mesoderm and endoderm, those that don’t ingress become ectoderm
Term
What is the primitive node and where is it?
Definition
The organizing center at the anterior end of the primitive streak
Term
What developmental defect causes sacrococcygeal teratomas?
Definition
Gastrulation defects
Term
True or false: too much ventral mesoderm in posterior primitive streak causes sirenomelia, mermaid limbs.
Definition
False, too little
Term
When does the primitive streak disappear?
Definition
When the anterior streak cells form dorsal mesoderm and posterior cells form ventral mesoderm.
Term
Define what axial, paraxial, intermediate, and lateral plate mesoderm become
Definition
notochord, somite, kidney, body wall and gut
Term
Define structures you see in twins from the 2 cell stage, inner cell mass stage, gastrulation
Definition
2 placentas and 2 amniotic cavities, 1 placenta and 2 amnio cavs (most common), 1 placenta and 1 amnio cavs
Term
Neural plate
Definition
thickening of the ectoderm induced by the mesoderm, start of neuralation
Term
The neural tube forms the CNS and what 3 brain vesicles?
Definition
Forebrain, midbrain, hindbrain
Term
How many ventricles does the brain have filled with cerebral spinal fluid?
Definition
4
Term
Failure of neural tube closure causes what?
Definition
Spina bifida and execephaly
Term
The lateral plate is not segmented but form two layers of mesoderm what are they what do they do?
Definition
Splachnic visceral meso which surrounds organs, and somatic parietal meso which forms the body wall
Term
Where does the heart and vasculature form?
Definition
Lateral visceral plate
Term
Somites, formed in the paraxial mesoderm, give rise to what 3 groups of cells?
Definition
Sclerotome (bone, vertebral column, cartilage), myotome (muscle), dermatome (dermis) each is innervated by the CNS next to the somite
Term
Endoderm has 3 divisions, fore/mid/hindgut, what do they give rise to?
Definition
Esophagus, trachea, stomach, liver, pancreas; duodenum, small intestine, transverse colon; colon, rectum, urinary bladder
Term
True or false: head neural crest cells migrate into pharyngeal arches and form most of the skull, face, and neck regions.
Definition
True
Term
What do the trunk neural crest cells form?
Definition
Melanocytes, schwann cells, dorsal root ganglia, autonomous nerve system (para/symapathetic)
Term
What are these disease from: Hirschprung, Piebald, Waardenburg?
Definition
Neural crest developmental problems
Term
Length of full term pregnancy since conception and since LNMP
Definition
38, 40
Term
Fetal size/weight 9 weeks, term birth size weight
Definition
.25 ounce 50mm, 7.5 lbs 14in
Term
What 3 hormones does the placenta produce?
Definition
Progesterone, estrogen, sommatotropin
Term
Tru or False: The placenta is derived from trophoblastic/chorionic tissue
Definition
true
Term
All major organs of fetus develop after what trimester?
Definition
First
Term
Fetus can survive birth at end of what trimester?
Definition
Second
Term
What is the most common estimate of fetal age?
Definition
CRL crown rump length
Term
What are the major chemical determinants of fetal growth?
Definition
Glucose, amino acids, insulin
Term
What is the risk to the fetus of MRI and CT?
Definition
None, Radiation
Term
What percent of all live births have major structural anomaly?
Definition
3%
Term
Do major anamolies occur in late embryos?
Definition
No, early embryos, 15%
Term
Nucleosomes
Definition
the basic repeating packets of chromatin
Term
Epigenetics
Definition
changes in gene expression through DNA modification/methylation as well as manipulating histones
Term
Why would cancers methylate certain epigenetic pathways?
Definition
To modify gene expression to gain favorable growth or suppress a tumor suppressor gene
Term
What epigenetic modification leads to transcriptional silencing?
Definition
Methylation
Term
What do epigenetic drugs do?
Definition
They attempt to modify epigenetic pathways in cancer cells by demethylating genes and therby unsilencing them
Term
These three considerations, compensate for mutation, replace/inactivate mutant gene, provide a pharmacological effect for disorder(cancer), refer to what process?
Definition
Gene therapy and gene medicine
Term
What are the advantages and disadvantages of ex vivo and in vivo gene therapy?
Definition
Controllable but difficult to do, can access many cell types but virus could spread and lose control
Term
Why are there so many types of viral vectors?
Definition
Because they can be stable, transient, and require cell division
Term
What are two non-viral vectors and why aren’t they used?
Definition
Naked DNA and liposomes, because they have a low efficiency and have transient expression
Term
What are three risks of gene therapy?
Definition
Reaction to vector, activate oncogene, inactivation of essential gene
Term
How is tissue differentiation in dorsal-ventral axis regulated, even at a distance?
Definition
Morphogen gradients of growth factor signals released by organizing centers, BMP and Chordin
Term
What is the process called where protein kinases phosphorylate transcription factors in the cytoplasm to induce transcription in the DNA?
Definition
Signal transduction
Term
A morphogen gradient can be induced by either a growth factor ______ or inhibited locally like __________?
Definition
BMP gradient, Chordin
Term
Homeodomain
Definition
DNA-binding domain in Hox genes
Term
Homeobox
Definition
nucleac acid sequence encoding a homeodomain
Term
Hox gene
Definition
39 genes from 4 complexes that orchestrate the pattern formation in the anterior-posterior axis
Term
What does colinearity of the Hox gene refer to?
Definition
They are arranged in the genome in the same order they are expressed, both spatially and temporally
Term
How is hox gene expression activated?
Definition
Retinoic acid via a nuclear receptor
Term
How is a nuclear receptor different from a growth factor receptor?
Definition
The growth factors induce a signal cascade which activates transcription factors, nuclear receptors are ligand (which pass through the membrane) activated transcription factors
Term
Where do adult stem cells reside?
Definition
Specialized niches, like bone marrow, adipose
Term
Are adult stem cells totipotent?
Definition
No, multi-potent
Term
What is a knockout mouse?
Definition
A mouse who genes have been altered/mutated/added to study disease pathology or embryological changes
Term
How is a knockout mouse created?
Definition
loxP-cre for cell specific recombination or embryonic cells are introduced to mutated genes via homologous recombo which creates chimeric animal then offspring analyzed for trait
Term
How do transgenic mice mirror human disease?
Definition
By giving them traits to model various types of disease like cancer
Term
Which weeks of development involve these stages of morphogenesis: implantation, embryogenesis, fetal period?
Definition
1-3, 4-7, 8-birth
Term
Damage during implantation usually results in what?
Definition
Spontaneous abortion
Term
Damage during embryogenesis usually affects what?
Definition
Multiple organs and malformations
Term
Disruption and deformations occur during what period?
Definition
Fetal period
Term
What are these indicators of in a chemical: infertility, spon abortions, growth deficiency, alterations of morphogenesis, alteration of organ system function?
Definition
Teratogenicity
Term
What factors affect teratogenicity?
Definition
Dose, timing, host susceptibility, interactions with other environmental factors
Term
How many categories of teratogens are there and what are they?
Definition
4, infectious, physical, drugs, maternal diseases
Term
Define these types of abnormal morphogenesis: Malformation, deformation, disruption, dysplasis.
Definition
Abnormal formation of structure, impact of mechanical forces on normal structure, destruction of previously normal structure, normal structures made out of abnormal tissue
Term
Describe the functional subdivisions of the nervous system.
Definition
The sensory composed of somatic and visceral, and the motor composed of ANS and somatic
Term
Describe the structural subdivisions of the nervous system.
Definition
The CNS composed of the brain and spinal chord, and the PNS which includes the ANS, nerves(cranial/spinal), and ganglia
Term
Describe the basic structure and function of neurons.
Definition
Composed of dendrite, cell body, and axons; functions to transfer signals
Term
Describe the function of glial cells
Definition
non-nueronal cells that myelinate neuronal axons. Oligodendrocytes in the CNS, schwann in the PNS
Term
What is the difference between oligodendrocytes and schwann cells?
Definition
Oligos in CNS and processes surround many axons, schwann processes myelinate only 1 axon
Term
Describe the 4 basic structures of the brain.
Definition
Cerebrum(FPOT), diencephalons(thalamus,hypothal), brainstem(midbrain,pons,medulla), cerebellum
Term
Describe the 4 basic regions of the spine.
Definition
Cervical thoracic lumbar sacral
Term
Where if the location of grey and white matter in the brain and spine?
Definition
Brain-grey out, white in; spine- white out, grey in
Term
Difference between grey and white matter?
Definition
Grey is cell bodies, white is myelinated axons
Term
What is the difference between the dorsal and ventral horns of the spinal column?
Definition
Dorsal = sensory neurons, ventral = motor
Term
What does the central canal of the spinal chord contain?
Definition
CSF
Term
The pia, arachnoid, and dura mater are what?
Definition
Meninges covering the CNS and regulate flow of CSF
Term
Which “mater” is wraps the brain and spinal chord?
Definition
Pia mater
Term
What is the special membrane in the ventricles of the brain that make CSF?
Definition
Choroid plexus
Term
Describe the flow and removal of CSF.
Definition
Choroid plexus, ventricles(1-4), subarachnoid space, dural veinous sinuses, blood
Term
Where do the cranial nerves and the spinal nerves innervate?
Definition
Head/neck, spine/body
Term
What two components form the spinal nerve?
Definition
The dorsal sensory nerves, and ventral motor nerves
Term
Describe the structure and function of a psuedounipolar neuron.
Definition
Cell body, peripheral process(body), central process (CNS); sensory neuron derived from neural crest cells
Term
Describe the function of a somatic motor neuron.
Definition
Multipolar neural cell controls muscles, with dendrites, cellbody, axons derived from neural tube
Term
Where is the cell body located for somatic motor and somatic sensory cells?
Definition
Dorsal root ganglion in spine and grey matter nuclei in brain, ventral horn
Term
Describe the neuromuscular junction.
Definition
Motor unit (1 axon + muscle fibers) synapse of motor neuron fires Ach, sarcolemma nicotinic receptors fire, ion channels, muscle depolarization
Term
What are these mechano/noci/thermo/proprioreceptors?
Definition
Somatic sensory receptors
Term
Dermatome
Definition
the area of cutaneous innervation provided by a single dorsal root and ganglion
Term
Why is a dermatome map used to diagnose dorsal root lesions?
Definition
It can identify sources of nerve problems by sections
Term
What does hCG do?
Definition
Stims the LH receptor on corpus luteum to maintain it and keep the luteum creating progesterone which maintains uterine lining
Term
What are the 3 discriminating features of Fetal Alcohol Syndrome?
Definition
Thin upper lip, smooth philtrum, short palpebral fissues
Term
Why is transplanting embryonic cells riskier than chord blood stem cells?
Definition
Embryonic cells more likely to develop into tumor
Term
Is genomic imprinting a mechanism of epigenetic inheritance?
Definition
Yes
Term
Are histone actelyases involved in gene silencing?
Definition
Yes
Term
What is anotia?
Definition
Absence of an ear
Term
What does RU486 do?
Definition
It inhibits the progesterone receptor, making the uterus unviable for the fetus.
Term
How does a transgenic mouse differ from a knockout/in mice or conditional mutant mice?
Definition
It does not require homologous recombination of the ES to create one.
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