Embryology Flashcards
What happens to the zone Pellucida once a sperm penetrates the oocyte (corona radiate, zone pellucid, oocyte membrane)?
Zone pellucid becomes impenetrable to other sperms.
What is arrested in prOphase of Meiosis I until Ovulation?
1ry (primary) Oocytes –> 2N
A 2ry oocyte (1N) is arrested in which phase of Meiosis II until fertilization?
Metaphase II until it is fertilized by sperm
Cleavage of the blastomeres occurs where in the female body?
Uterine tube
What is the term for 16-32 cells that have gone through mitotic divisions in the uterine tube?
Morula –> then enters the UTERUS at this size
What is a Blastocyst?
A fluid filled space which appears after the morula enters the uterus
What are the two layers of the Blastocyst?
- Inner cell mass - EMBRYOBLAST 2. Outer cell mass - TROPHOBLAST
When and where does implantation occur?
End of week 1 and occurs in the posterior wall of the superior part of the uterine body (zone pellucid disappears) - ends at week 2
Once the Blastocyst adheres to endometrial epithelial, what begins to differentiate into cytotrophoblast and Syncytiotrophoblast?
TROPHOBLAST - SYNCYtiotrophoblast erods the endometrial blood vessels –> uteroplacental circulation formed
What is an ectopic pregnancy and what are the symptoms?
- Ectopic Pregnancy is implantation OUTSIDE the uterus (common = tubal pregnancy) 2. Symptoms - abdominal pain and missed period
What is the term for an abnormal pregnancy that occurs in the INFERIOR SEGMENT of the UTERUS?
Placenta Previa Symptoms = vaginal bleeding
What occurs during the SECOND week of development? Third? Fourth?
2nd = Bilaminar Disc forms 3rd = Trilaminar Disc 4th week = four limbs appear
During week, what are the 4 “period of 2’s” events?: 1. What does the inner cell mall differentiate to? 2. Outer cell Mass? 3. What two cavities form? 4. The extra embryonic mesoderm splits into what layers?
- Epiblast and hypoblast (bilaminar disc) 2. Cytotrophoblast and suncytiotrophoblast 3. Amniotic Cavity and Yolk Sac cavity 4. Mesoderm –> Somatic and Splanchic Layers
What occurs during the third week of development? (Period of 3’s)
- Primitive streak appears 2. Epiblast (ECTOderm) cells migrate inward to form new cell layers –> ENDOderm and mesoderm 3. Gastrulation –> three germ layers appear (ecto, endo, mesoderm)
What are the two components of the placenta? (which is maternal and which is fetal?)
- Villous Chorion = Fetal 2. Decidua Basalis = Maternal (think: BASE is mom)
What are the three types of Chorionic Villi and what are the components of each?
- 1ry - Cyto and Syncytiotrophoblast 2. 2ry - 1ry and + mesenchyme core 3. 3ry - 2ry +vessels