ANAT 2130 Lecture Notes - Lecture 9: Decidua, Cytotrophoblast, Corpus Luteum
16 Oct 2016
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Document Summary
In all mammals, embryos develop in the uterus. Large organ [about 20cm (~8in) diameter, weighing about 0. 5kg (~1lb)], composed of mostly fetal tissue but some maternal tissue. Interface between mother and fetus, all maternal/fetal exchange occurs via placenta. Respiratory organ for fetus prior to birth. Excretory organ and interface for nutrient transfer. Important source of hormones that regulate female reproductive cycle, including: estrogens (progesterone and estriol, human chorionic gonadotrophin (hcg, a kind of growth hormone. Embryo develops inside a sac formed by the trophoblast. Lacunae form in walls of sac, contain maternal blood. Walls of lacunae grow and become highly irregular, increasing surface area. Meanwhile, cytotrophoblastic cells proliferate and fuse to form outer synctiotrophoblast. Embryo is connected to wall of sac by connecting stalk = precursor of umbilical cord. Early primary villi have core of cytotrophoblast covered by coast of synctiotrophoblast. Villus cores then become invaded first by embryonic ct (secondary villi), and then by embryonic blood vessels (tertiary villi)
