PHSL 3051 Lecture Notes - Lecture 28: Fetus, Cell Membrane, Inner Cell Mass
Document Summary
Corona radiata zona pellucida plasma membrane of secondary oocyte -- > cytoplasm of secondary oocyte. Egg surrounded by zona pellucida -- only 1 sperm cell can enter. If two sperm are on egg triploidy, lethal and kills zygote/embryo/fetus. In vitro fertilization: remove cell for testing then re-implanting. Hollow ball of cells: walls are trophoblasts. Implantation (about 7 days after fertilization: some bleeding can occur from implantation - seems like period, embryo begins development: yolk sac, amniotic cavity (water cavity), structures become the placenta. Umbilical veins: carries oxygenated blood into the fetus. Umbilical arteries: carries blood away from fetus. Allows o2 and other lipid soluble molecules to diffuse across placenta. Some medications can cross placenta and others cannot. Hcg is basis of pregnancy test: human chorionic gonadotropin. Steep increasing during initial months of pregnancy. Maintains the corpus luteum until the placenta is able to produce adequate levels of estrogen and progesterone.
