1.9 Intro to Embryology Flashcards
A specialized extracellular matrix surrounding the oocyte; transparent zone
Zona Pellucida
Supplies vital protein to cells, appears at ovulation, and disappears after fertilization
Corona Radiata
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
Capacitation
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
Acrosome reaction
Phases of acrosome reactions and key activities
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
Acrosomial enzyme which allows sperm to penetrate zona
Acrosin
Enzymes released which prompt the zona reaction which prevents polyspermy
Lysosomal enzymes
16-cell stage at day 3
Morula
Part of morula which gives rise to embryoblast
Inner cell mass
Part of morula which gives rise to trophoblast which becomes the placenta
Outer cell mass
Summary of events in week 1 (including hours/days)
Ovulation Fertilization (12-24 hours after) Cleavage and Morulation (30 hours) Blastocyst formation (4 days) Implantation (6 days)
Two differentiated layer of embryoblast
Hypoblast (small cuboidal)
Epiblast (high columnar)
Location of amniotic cavity
Epiblast