MCB 180 Lecture Notes - Lecture 7: Chorionic Villi, Decidua, Endometrium
Document Summary
Length of human pregnancy is variously described as 40 weeks, 38 weeks, or 37 weeks. Early development from fertilization until structuers characteristic of the species can be identified 8 weeks in human. Development from attainment of basic species structural plan until birth (8 weeks until birth) The synctiotrophoblast has several major functions during human pregnancy. Implanted human blastocyst in day 25 secretory phase endometrium. Note heavily coiled uterine glands in the lamina functionalis. The amniotic sac grows to suspend the fetus in amniotic fluid. Immature chorionic villi (8-12 weeks) have a multitude of trophoblastic buds or sprouts. Hcg binds to lh receptors on the corpus luteum to extend the functional life span of the corpus luteum. This phenomenon is called the maternal recognition of pregnancy . Hcg detectable as early as 7-8 days after fertilization. Cholesterol from mother"s liver converted to progesterone in placenta. Progesterone goes to fetal adrenal where it is converted to estrogen precursor dehydroepiandrosterone.