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Embryo
Embryology LECOM
153
Biology
Professional
08/01/2013

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Term
Three stages of embryonic development
Definition

Early development

embryonic period

fetal period

Term
Malformations
Definition
occur during organogenesis in the embryonic period
Term
Dysplasia
Definition
abnormal organization of cells into tissue i.e. teratoma
Term
Fertilization and Implantation occur during what stage of development?
Definition
First stage, Early development
Term
Organs and body parts form during this stage and are HIGHLY susceptible to injury
Definition
2nd stage- Embryonic period
Term
What organs are still susceptible to injury during fetal period?
Definition
Brain, eyes, ears, pallate, teeth, external genetalia
Term
Early development occurs in what time frame?
Definition
0 to 3 wks
Term
Embryonic period occurs in what time frame?
Definition
wks 3 to 8
Term
Fetal period occurs during what time frame?
Definition
wk 9 to birth
Term
Mitosis occurs at what part of cell cycle?
Definition
S phase
Term
Two identical cells with same chromosome # and content result upon completion of this process
Definition
Mitosis
Term
Congenital anomalies account for what % of infant deaths in the US
Definition
20%
Term
2ndary oocyte & spermatids are regarded as   what in mitosis?
Definition
1N Haploid
Term
Chromosome line up during which phase of mitosis
Definition

Metaphase

 

Term

Nuclear envelope and nucleolus disappear

during which phase of Mitosis

Definition
Prophase
Term
chromosomes are pulled apart during which part of Mitosis?
Definition
Anaphase
Term
Mitosis results in what?
Definition
2N, Diploid
Term
Meiosis results in what for males and females?
Definition

4 spermatids for males

1 ovum & 3 polar bodies for females

Term
Pachytene
Definition
Crossing over in prophase of Meiosis I, where daughter cells become genetically different from parent cell
Term
Meiosis creates how many daughter cells?
Definition
4, all haploid 1N
Term
Primordial germ cells are also known as what?
Definition
The yolk sac
Term
describe where gamete forming cells come from?
Definition

Come from epiblast during 2nd wk of development and migrate to yolk sac

 

germ cells migrate to lower thoracic region and multiply via mitosis

Term
Spermatogenesis takes place from ____ to _____
Definition
puberty til death
Term
What are the primordial germ cells in men/women?
Definition

Males= sertoli cells

Females= follicular cells

Term
What cells secrete testosterone to begin the process of spermatogenesis?
Definition
Leydig cells
Term
Difference between spermatogenesis & spermiogenesis
Definition

Spermiogenesis is conversion of spermatids to mature sperm

 

Spermatogenesis begins with spermatogonia goes through mitosis, then meiosis, and results in 4 spermatids, 1N 

Term
What is the final step in maturation of the sperm?
Definition
Capacitation; this occurs in the vagina near cervix
Term
Where do sperm go once spermiogenesis is complete?
Definition
Into the seminiferous tubules
Term
Steps of spermatogenesis
Definition

1-primary germ cells>> spermatogonia>> primary spermatocyte via mitosis

 

2- primary spermatocyte>> 2ndary spermatocyte>> ends in 4 spermatids via meiosis

Term
By week 12 of development, oogonia enter first meiotic prophase and become dormant until when?
Definition
menstruation
Term
The capsule of the oocyte and the follice become what together?
Definition
the Ovarian follicle
Term
When does ovulation begin?
Definition
At puberty
Term
Two stages of ovarian cycle
Definition

1- Follicular

2- luteal phase

Term
Primordial follicles thicken into what type of cells as a result of changes in LH and FSH
Definition
Cuboidal cells
Term
What hormones spike right before day 14 of the menstrual cycle?
Definition
FSH and LH
Term
Primary follicle in female gametogenesis becomes what ?
Definition
A Graafian follice
Term
What are Graafian follicles?
Definition
They are 2ndary oocytes
Term
When is the first meiotic division completed  in female gametogenesis?
Definition
Its completed prior to ovulation forming a 2ndary oocyte and the 1st polar body
Term
Under what circumstances does the 2nd division of meiosis occur in female gametogenesis?
Definition
ONLY if fertilization takes place
Term
3 differences between male & female gametogenesis
Definition

1- Oogenesis happens in utero vs. before puberty in males

2- definite # of oocytes vs. infinite # of spermatocytes

3. meiotic cycle for oocyte is 10-50yrs vs. 9 wks for spermatogenesis

Term
If there is no implantation, what happens to corpus luteum?
Definition
It degenerates and endometrium dissociates
Term
If there is implantion, what hormone is secreted?
Definition
HCG; which keeps corpus luteum producing progesterone for about 5 months
Term
Describe the process of ovulation
Definition

1- Day 14 of period, FSH & LH spike causing primary oocyte in Graafian follicle to resume meiosis

2- follicle ruptures and releases the oocyte

3- ruptured follicle forms corpus luteum

4- corpus luteum maintains uterine endometrium in a condition ready to receive an embryo

Term
what secretes HCG if implantion does occur during ovulation?
Definition
syncytiotrophoblast
Term
Patient has webbed neck, no ovaries, lymphedema of lower extremeties
Definition
Turners syndrome, 45x
Term
Patient born with skin folds, slanted eyes, facial abnormalities, and extra 21 chromosome
Definition
Downs syndrome
Term
child born with congenital heart defect, lowset ears, malformations of skeletal system
Definition
Trisomy 18
Term
child forebrain did not develop properly, also display intellect disability
Definition
trisomy 13
Term
Young male, has barr body, testicular atrophy, chromosome 47 XXY
Definition
Klinefelter syndrome
Term
Child has no substantial offset physical features, but is slow to speech
Definition
Triple XXX, 47
Term
microdeletion seen in patient on maternal chromosome 15; demonstrates poor motility, cannot speak, long periods laughter
Definition
Angelman syndrome
Term
patient has hypotonia, obesity, hypogonadiasm, and microdeltion on paternal chromosome
Definition
Prader willi syndrome
Term
what is a Barr body
Definition
Inactive x sex chromatin caused by non disjunction
Term
Role of the corpus luteum
Definition
secretes progesterone & estrogen, maintains pregnancy
Term
Steps in fertilization
Definition

1- sperm gets through corona radiata

2- sperm gets through zona pellucida

3- plasma membranes fuse together

4- completion of meiotic 2nd division

5- formation of the male pronucleus

6- male and female pronucleus fuse forming zygote

Term
the sperm has crossed the corona radiata and now is attempting to penetrate the zona pellucida. what enzyme is released?
Definition
the acrosome enzymes
Term
Zona rxn and Cortico rxn do what?
Definition

Zona- changes conformation of zone receptor on zona pellucida

cortico- changes plasma membrane to prevent other sperm from getting through

Term
Diploid genome, beginnings of cleavage, genetic sex of embryo are all objective results of what process?
Definition
Fertilization
Term
Fertilization of the oocyte is now how many 'N' upon completion?
Definition
2n
Term
Contraceptive pill, depo-provera, and ru-486 ALL have what in common?
Definition
They contain progesterone, which moderates feedback of FSH. It also makes uterine secretions more viscous & harder for sperm to move through
Term
Implantation will likely not occur with out what hormone?
Definition
progesterone
Term
At what point does the zygote begin cleavage?
Definition
within 24hrs of fertilization
Term
The zygote has been fertilized and is now undergoing several mitotic divisions. What is this process called?
Definition
Cleavage; theres not growth and it remains with the zona pellucida
Term
Cells are increasing gap junctions and surface contact with other cells, while shifting their cytoplasm. Whats happening?
Definition
Compaction
Term
Following compaction what is formed?
Definition
Morula
Term
Where does fertilization occur?
Definition
Uterine tube
Term
How many days does it take from fertilization to implantation?
Definition
5-6
Term
At day 4, what is the zygote ?
Definition
A blastocyst
Term
Ultrasound shows that a womans fetus has implanted in the lower part of the uterus and is now covering her cervix. What is this called and what are the risks associated with this condition?
Definition
Placenta previa, with possible infection and bleed risk
Term
Upon ultrasound, a young womans child is seen with a disconnected placenta. What is this referred to as?
Definition
placenta abruption
Term
Placenta accreta is what?
Definition
abnormal growth of the placenta
Term
What are the two parts of the blastocyst?
Definition

Emrbyoblast- forms embryonic tissues

Trophoblast- forms placenta

Term
The epiblast and the hypoblast come from what part of the blastocyst
Definition
embryoblast
Term
The cytiotrophoblast and the syncytiotrophoblast come from what part of the blastocyst
Definition
the trophoblast
Term
Husban and wife come in with pregnancy issues. Upon further inspection, its determined woman has a UTI, how could this affect the fetus?
Definition

oligohydrominos- too little amniotic fluid

 

Term
Why is 2nd week called the week of 2's?
Definition

Begins with 2 embryonic layers

embryoblast forms 2 layers

trophoblast forms 2 layers

2 cavaties w/in the embryo form

Term
How do Hydatidiform moles come about?
Definition
They form the fertilization of an empty oocyte. Causes high levels of HCG. its made of placenta and trophoblast. and has swollen villi
Term
Partial pregnancy moles have what specific chromosomal characteristic?
Definition
They are triploid XXX
Term
The 3 germ layers arise through what process?
Definition
Gastrulation, from the epiblast
Term
The head of the epiblast looks similar to what shape?
Definition
Head of a tear drop
Term
What types of cells are in the notochord?
Definition
Mesoderm and endodermal cells
Term
how does the notochord develop?
Definition
It develops as a hollow tube-like invagination of cells from the primitive pit
Term
CNS development, anatomic midline/orientation is all a function of what important embryological structure?
Definition
Notochord
Term
Where are Neurenteric cysts found and how common are they?
Definition
They account for 0.7-1.3% of spinal axis tumors. These rare lesions result from the inappropriate partitioning of the notochordal plate during the third week of human development
Term

Head-tail fold

Making a flat embryo tubular

going from flat to partially closed structure

What is the process for doing all of these tasks?

Definition
Embryonic folding
Term
What happens to the trilaminar embryo as a result of embryonic folding?
Definition
It becomes a tubular embryo
Term
What two things play a major role in determination of body axes?
Definition
Primitive streak and primitive node
Term
An x ray image shows a man with his organs  as a mirror image of their correct location. What is this?
Definition
Situs Inversus
Term
Upon xray imaging, the heart was found to be on the right side of the body. What is this?
Definition
Dextrocardio
Term

Alcohol use could contribute to which body axes defects?

 

Definition
Holoprosencephaly, when midline cells are deficient
Term
Olgo- (not enough amniotic fluid) would cause what possible defect in a stillborn fetus?
Definition
sirenomelia or mermaid legs due to abnormal development of caudal regions
Term
Describe Sacroccygeal teratoma
Definition
It occurs as a result of the primitive streak and pluripotent cells. Teratoma= tumor. This condition is found on the tail bone usually, but can form on multiple tissues
Term
When is the embryonic period?
Definition
Between weeks 3 and 8
Term
What are the main events of the embryonic period?
Definition

3 cell layers undergo differentiation

Organogenesis- organ systems form

 

Term
What exactly is the trilaminar embryo?
Definition
Its an embryo in its early development that exists in three germ layers, these layers arise from the epiblast during the 3rd week, right after gastrulation
Term
What becomes of the ectoderm?
Definition
it becomes the surface of the skin, and undergoes neurulation. After neural folding, the neural tube is formed, which forms all of the CNS
Term
What happens to the mesoderm during the embryonic period?
Definition

it divides 3 ways:

1- axial skeleton (paraxial)

2- urinary/genital system (intermediate mesoderm)

3- later plate

 

Also addds to development of blood

Term
The brain and spinal cord is forms from what extodermal derivative?
Definition
The neuroectoderm
Term
What day does the CRANIAL neuropore close in the process of neural folds?
Definition
Day 24/25
Term
What day does the CAUDAL neuropore close during neural folding?
Definition
DAY 26/27
Term
Which cells end up going into the gut, skin and migrate through the embryo? It is another ectodermal derivative.
Definition
Neural crest cells. Detach from neural tube and migrate
Term
Neural crest cells form what???
Definition

GANGLIA! 

parasympathetic ganglia

sensory ganglia

autonomic and dorsal root ganglia

Term
Ear, teeth, eye, anterior pituitary gland, hair, nails, epidermis, mammory glands... These are all arise from what germ layer? and what part
Definition
SURFACE, ECTODERM
Term
How many mesoderms are there? Their names are?
Definition
3: paraxial, intermediate, and lateral plate
Term
Which germ layer contributes to the yolk sac?
Definition
Endoderm
Term
Endodermal forms what?
Definition
Epithelial lining, allantois, arenchyma, stroma of tonsils/thymus
Term
Epithelium develops from what germ layer?
Definition
it can develop from any of the 3 germ layers
Term
Endoderm and Ectoderm malignant tumors are referred to as what?
Definition
Carcinomas
Term
Mesoderm benign tumors are called what?
Definition
Angiomas
Term
Ectoderm and Endoderm benign tumors are called?
Definition
papilloma/adenomas
Term
Mesoderm malignant tumors are what?
Definition
sarcoma
Term
Define teratoma
Definition
A tumor composed of cells from more than one germ layer
Term
Tumors in the muscle area of the mesoderm are called what
Definition

Myoma- benign

myosarcoma- malignant

Term
When is the fetal period?
Definition
It is 9wks until birth
Term
What parts of the fetus are still susceptible to injury during this time?
Definition
brain, eyes, ears, pallate, genitalia, teeth
Term
A woman comes in for an ultrasound around her 12th wk of pregnancy. The doctor sees all the organ systems developed and the figure of a human now visible. What period of development is this?
Definition
Fetal period
Term
Where is the major site of erythropoiesis at wk 9 of the fetal period?
Definition
Yolk sac
Term
A woman would like to know when she will be able to see whether her child is a male or a female. What week should she come in for an ultrasound?
Definition
Week 9 the external genetalia are visible
Term
Red blood cells are first made in what site?
Definition
the yolk sac
Term
its week 13-16, what do we know about this time of the fetal period?
Definition

Sites of ossification and bones form

 

The eye is moving and facing forward

Term
The primary ovarian follicle and testes descend during what weeks
Definition
wk 17-20
Term
What is being secreted in the lungs by weeks 21-25?
Definition
Surfactant
Term
The spleen is making blood cells, but its approaching week 28, whats going to make the blood cells now?
Definition
Bone marrow
Term
The finishing period of pregnancy takes place when?
Definition
weeks 35-38
Term
The liver, the bone marrow, the yolk sac, and the spleen are all responsible for making blood, but at what time periods?
Definition

0-12wks yolk sac

12-30wks liver

12-24wks spleen

by wk 30 bone marrow

Term
Which two organs are making blood at the same time during the fetal period?
Definition
liver and spleen
Term
A first time mom is pregnant at age 48.. What procedure may the doctor suggest to check the health of the baby?
Definition
Amniocentesis
Term
Why would someone get an amniocentesis done?
Definition
IF.. parents are X linked arriers, neural tube defects, chromosomal abnormalites, previos downs syndrom child, mother is in elderly age
Term
Primary ovarian follicles form and testes descend during what weeks
Definition
17-20
Term
Surfactant is secreted into lungs during what week
Definition
21-25
Term
Fetus can breathe, CNS controls body temp at how many weeks
Definition
26-29
Term
what week does bone marrow start making blood
Definition
28
Term
cardiovascular and respiratory prep has begun for baby to enter the world at which weeks?
Definition
35-38
Term
A primordial follice has what type of cells?
Definition
Squamous follicular cells
Term
pruning of the glycocalix takes place when?
Definition
During capacitation
Term
Shedding of the zona pelucida allows what?
Definition
Impantation
Term
The primary yolk sac is lined by what?
Definition
Hypoblast
Term
Primary stem villus consist of what?
Definition
Syncytio and cytotropho
Term
Notochord derives from which 2 layers
Definition
Endoderm and mesoderm
Term
Persistence of the primitive streak will cause what?
Definition
Saccrocramol teratoma
Term
Placenta is formed from what?
Definition
Trophoblast
Term
[image]
Definition

Amniotic cavity surrounded by epiblast ONLY

Yolk sac lined by hypoblast ONLY

 

Uterine epithelium is in contact with syncytiotrophoblast ONLY

Term

2ndary stem vili consist of what 3 things

 

Definition
Cyncitiotropho, syncytiotropho, extraembryonic endoderm
Term
Primitive streak forms from what layer
Definition
Epiblast
Term
Chorionic plate comes from where?
Definition
Somatopleuric of extraembryonic mesoderm
Term
When primary stem villi become 2ndary stem?
Definition
DAY 16
Term

Between mother and fetus are what 4 layers

 

Definition
Syncytiotropho, cytotropho, loose CT, and endothelum of villus capillaries
Term
The chorion comes from where? and is composed of what?
Definition

1- trophoblast

2- somatopleuric, cytotropho, syncytotropho

Term
[image]
Definition
All placenta and trophoblast- a hyaditiform mole
Term
[image]
Definition
Top part= head of epiblast
Term
[image]
Definition
A longitudinal fold
Term
[image]
Definition
A transverse fold
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