Weeks 9-40 Flashcards
What happens in weeks 9-40?
Growth of fetus
What does endovascular invasion into uterine wall by trophoblast result in?
Epithelial to endothelial transformation
Growth of larger vessels
Hybrid vessels w/ cells from both embryo and mother
What two membranes fuse to form placenta?
Decidua basilis (uterus) and chorion frondosum
What two membranes fuse to form fetal membrane?
Chorionic and amniotic membranes
What is the function of the placenta?
Exchange of gases (O2 and CO2)
Exchange of nutrients and electrolytes
Transmission of maternal antibodies (IgG)
Hormone production
Amnio-ectodermal junction - “umbilical ring” - consisting of connecting stalk, yolk stalk, chorionic cavity connection
What hormones does placenta release?
Progesterone, Estriol, hCG, somatomamotropic
What structure produces progesterone until the placenta forms?
corpus luteum
What is the function of somatomamotropin?
Tells the mother’s body to give nutrients preferentially
to the fetus and also starts changes in breast tissue
What is function of hCG?
Maintain corpus luteum
What type of twins arise from two oocytes?
dizygotic (fraternal) – have separate fetal membranes
What type of twins arise from one oocyte?
monozygotic (identical)
Q: What type of twins may have one or two amniotic cavities?
A: monozygotic
Q: What type of twins always have a common chorionic cavity?
A: monozygotic
What type of twins have two separate chorionic cavities?
Dizygotic
What is the space called that develops between the splanchnopleuric and somatopleuric extraembryonic mesoderm?
A: chorionic cavity
Q: What layer is the source of all three germ layers?
A: epiblast
Q: The appearance of the notorchord causes what?
Thickening of the ectoderm (neural plate). The induction of the neuroectoderm is called neurulation.
Q: Bones and cartilage of the face arise from what?
A: neural crest
Q: The dorsomedial portion of the paraxial mesoderm will become what? Dorsolateral portion?
Epaxial (back) muscles
The dorsolateral portion migrates to become the precursor oflimb and body wall musculature
What is the somatic/parietal mesoderm contiguous with?
the extraembryonic mesoderm covering the amnion
Q: What is the splanchnic/visceral mesoderm contiguous with?
the extraembryonic mesoderm covering the yolk sac
What layer of the lateral plate mesoderm will cover the organs and form the wall of the gut?
Visceral/splanchnic layer along with underlying endoderm will form the wall of the gut
Q: What layer of the lateral plate mesoderm will line the intraembryonic cavity?
the parietal/somatic layer along with the overlaying ectoderm will line the intraembryonic cavity
