Health Sciences 4320A/B Lecture 9: Health Sciences 4320A/B Lecture :

• School: Western University
• Department: Health Sciences
• Course: Health Sciences 4320A/B
• Professor: Christine Bell

Document Summary

Uterus at different phases of the menstrual cycle: endometrial lining has to be prepared to receive an embryo. These arteries spread into the endometrium and eventually interact with placental cells of the fetus. Lining itself is growing: basalis layer, myometrium most inward layer, closest to the mother. Placenta: arteries and veins from the umbilical cord interact with the endometrium, maternal side. If these cells were to invade further, it would be a problem: can be destructive that upon delivery, the entire uterus needs to be removed, generally, invades the decidua basalis, and functionalis layer will interact. Day 8: embryo starts to invade into endometrial lining. Eventually becomes completely encased in endometrial lining. Cytotrophoblast surrounds entire conceptus, remains closer to the embryo. Syncytiotrophoblast blob, no cell membranes, multinucleated. Day 9: primary umbilical vesicle starts to make extraembryonic mesoderm, extraembryonic mesoderm. Comes from arteries and glands of the uterus that become degraded by the syncytiotrophoblast.