1.9 Intro to Embryology

Question 1

A specialized extracellular matrix surrounding the oocyte; transparent zone

Answer 1

Zona Pellucida

Question 2

Supplies vital protein to cells, appears at ovulation, and disappears after fertilization

Answer 2

Corona Radiata

Question 3

Is the period of conditioning of the female reproductive tract; lasts 7 hours; removal of glycoprotein coat and seminal plasma protein from the plasma membrane of spermatozoa

Answer 3

Capacitation

Question 4

Occurs after binding of the spermatozoa to the zona pellucida; induced by zona proteins and culminates in the release of enzymes needed to penetrate the zona pellucida

Answer 4

Acrosome reaction

Question 5

Phases of acrosome reactions and key activities

Answer 5

Phase 1: penetration of corona radiata; other sperms aid the fertilizing sperm in penetrating
Phase 2: Penetration of Zona Pellucida; Binding and acrosome reaction, release of acrosomial enzyme; sperm penetrates
Phase 3: Fusion of oocyte and sperm cell membranes; completion of oocyte’s meiosis II

Question 6

Acrosomial enzyme which allows sperm to penetrate zona

Answer 6

Acrosin

Question 7

Enzymes released which prompt the zona reaction which prevents polyspermy

Answer 7

Lysosomal enzymes

Question 8

16-cell stage at day 3

Answer 8

Morula

Question 9

Part of morula which gives rise to embryoblast

Answer 9

Inner cell mass

Question 10

Part of morula which gives rise to trophoblast which becomes the placenta

Answer 10

Outer cell mass

Question 11

Summary of events in week 1 (including hours/days)

Answer 11

OvulationFertilization (12-24 hours after)
Cleavage and Morulation (30 hours
)Blastocyst formation (4 days)
Implantation (6 days)

Question 12

Two differentiated layer of embryoblast

Answer 12

Hypoblast (small cuboidal)

Epiblast (high columnar)

Question 13

Location of amniotic cavity

Answer 13

Epiblast