Zusammenfassung der Ressource
Embryology Lecture 1: From Fertizilation to Gastrulation
- Bottom Line
- Fertilization in ampulla of uterine tube
- fusion of pronuclei -> division of blastomeres -> MORULA -> compaction of blastomeres so fluid into center -> BLASTOCYST w/fluid filled cavity & inner cell mass = EMBRYO; outer cell mass = TROPHOBLAST
- pregnancy -> syncytiotrophoblast secretes hCG -> maintains corpus luteum -> makes progesterone -> maintain pregnancy
- Infertility 15-30%; ART ^ prematurity, low birth weight, & birth defects
- no fertilization -> no hCG -> corpus luteum regresses -> no progesterone -> menstruation & prep for next cycle
- 2nd Week
- Trophoblast
- Cytotrophoblast (makes cells)
- Syncytiotrophoblast (forms syncytium - blastocyst into uterine endometrium))
- Inner cell mass @ one pole of blastocyst -> germ disc (epiblast & hypoblast)
- 2 cavities - amniotic (dorsal to epiblast); yolk sac (ventral to hypoblast)
- syncytio - this whole part - ASK QUESTIONS WHAT IS HAPPENING
- "Week of 2s" - 2 layers trophoblast (synctio- and cytotrophoblast), 2 layers embryoblast (epiblast & hypoblast), 2 cavities (amniotic & yolk sac - then chorionic cavity), 2 layers extraembyonic mesoderm (somatic & splanchnic)
- 3rd Week - GASTRULATION
- 3 Germ Layers from epiblast
- Ectoderm
- Skin, CNS, PNS, eyes, internal ear, neural crest cells
- Mesoderm
- bones, connective tissue, urogenital system, cardiovascular system
- Endoderm
- gut & gut derivatives (liver, pancreas, lungs, etc)
- 3 cavities - amniotic, yolk sac, chorionic