NATS 1675 Lecture Notes - Uterine Cavity, Blastocoel, Trophoblast
4 Apr 2013
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Natural science human development lecture # 16 powerpoint notes. From egg to the living body: the pre-embryonic period: cleavage and. An introduction to the biology of human. Chapter 17, development and aging, pages 185 . Cleavage partitions the zygote into a ball of many smaller cells. Leading to different developmental fates for different cells. On 1st day, fertilization occurred in the upper third of oviduct. ), single-celled zygote undergoes cleavage mitotic divisions. Cleavage continues to rapidly as the pre-embryo moves through rest of oviduct toward uterus. Sometimes mass of cells splits into 2: monozygotic twins identical twins from 1 zygote. Genetically identical same gender: incomplete splitting results in conjoined twins. Fraternal twins occur when two secondary oocytes are released during ovulation fertilized by two separate sperm: dizygotic twins non-identical twins from 2 zygotes. Not genetically identical may be different gender. Is as the morula stage a solid ball of 12 or more cells.
