PHSI 208 Lecture Notes - Lecture 6: Fallopian Tube, Blastocyst, Endometrium
Document Summary
Topics: fertilization and implantation; blastocyst and placenta; parturition and lactation. The developing embryo implants in the endometrium. (1) ovulation, (2) day 1: fertilization, (3) days 2 4: cell division takes place, (4) days 4 5: blastocyst reaches uterus. (5) days 5 - 9: blastocyst implants. Progesterone slows down smooth muscle contraction in fallopian tubes. Blastocysts secrete enzymes allowing it to burrow into the uterine wall and it becomes engulfed. It obtains oxygen and nutrients from the mother through the placenta and umbilical cord. The outer cell layer of the blastocyst forms an extra embryonic membrane (chorion), enclosing the embryo and forming the placenta. The inner cell mass forms the embryo, and other extraembryonic membranes: Some material is exchanged across placental membranes by diffusion, but other material may be transported. The outer layer of cells, chorion, that will become placenta begin to form chorionic villi that penetrate vascularized endometrium. The villi secrete enzymes that break down walls of maternal blood vessels.
