Embryology Quiz

Embryology

• Embryology is the branch of medicine concerned with the study of embryos and their development.

Ovulation

• Around the midpoint of the menstrual cycle (~day 14), a single egg is ovulated and swept into the oviduct.
• The egg has a corona radiata, zona pellucida (ZP-1, -2, and -3), and cortical granules.

Fertilization

• Fertilization usually occurs in the ampulla of the oviduct within 24 hrs.
• The embryo is still contained in the zona pellucida after fertilization.

Blastocyst Development

• Early blastocyst stage occurs around day 3.
• Later blastocyst stage occurs around day 5.
• The blastocyst has an inner cell mass and a blastocoele.

Monozygotic Twinning

• Monozygotic twinning typically occurs during cleavage/blastocyst stages.

Hatching and Implantation

• Hatching of the blastocyst from the zona pellucida occurs just prior to implantation.
• Implantation typically occurs in the upper portion of the uterus.
• Ectopic implantation occurs when implantation takes place somewhere other than the upper portion of the uterus.
• Implantation can lead to life-threatening hemorrhage if it occurs in a location other than the uterus.

Complications

• Tubal pregnancy is a type of ectopic pregnancy.
• Rupture of the ectopic pregnancy can lead to life-threatening hemorrhage.