BMS 360 Lecture Notes - Ectopic Pregnancy, Placenta, Ovulation
Document Summary
Sex steroids: low prepuberty, unchanged at onset of puberty, then adult level. Feedback: operative and sensitive decreasing in sensitivity operative at adult level. Gonadotropins: low increasing adult level kisspeptin protein. Girls require ~17% body fat to start puberty. Minimum amount of body fat must be maintained for regular cycles. Egg viable after ovulation for 24 48 hours. Utero-tubal junction - ~100-1000 sperm reach this point. Egg and sperm pronuclei fuse to form zygote nucleus. Cortical reaction: oocyte releases enzymes from cortical granules causing zona pellucida to harden and fewer receptors. Extrusion 2nd polar body, male and female pronuclei fuse. Days 2 4: cell division takes place. 96% in fallopian tube (so 4% in abdomen) Trophoblast cells proliferate and penetrate the endometrium implantation. If pregnancy occurs, the trophoblast produces human chorionic gonadotropin (hcg). The corpus luteum does not regress and continues to produce progesterone in response to hcg. Thus, the developing embryo signals the mother and preserves the corpus luteum.
