KINESIOL 1A03 Lecture Notes - Lecture 3: Pronephros, Mesonephros, Endodermic Evagination
14 Oct 2016
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From conception to birth: three stages: germinal period: first 2 weeks of development during formation of primitive germ layers, embryonic period: second to end of. 8th week, organ systems develop: fetal period: last 30 weeks, organ systems grow and mature. Terminology: clinical/medical events: date since last menstrual period (clinical age of unborn child, embryologists: post-ovulatory age (approximately 14 days less than clinical age) Many sperm cells attach to corona radiata of secondary oocyte. Slow block to polyspermy: intracellular release of ca2+ exocytosis of h2 o, oocyte shrinks zona pellucida denatures, zp3 becomes inactivated. Female nucleus undergoes second meiotic division: female pronucleus. Within the first few divisions, the cells are totipotent- cells are capable of becoming any tissue in the body. Trophoblast- will become the extra-embryonic tissues (placenta, amniotic tissues, chorion) Cilia in the uterine tubes propel the zygote back toward the uterus as the division goes on. Inner cell mass: will become the extra-embryonic tissues (placenta, amniotic tissues, chorion)
