NATS 1610 Lecture Notes - Zona Pellucida, Corpus Luteum, Meiosis
5 Feb 2014
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Human life has two main periods of development: prenatal, postnatal, the prenatal period begins at fertilization and ends at birth. Summary of early events during the pre-embryonic period: step 1: ovulation: a secondary oocyte is released from the ovary and swept into the oviduct, step 2: fertilization: a single sperm penetrates the secondary oocyte. The blastocyst has freed itself from the zona pellucida and can increase in size: step 6: implantation: the blastocyst attaches to the uterine lining (endometrium) and begins to digest its way inward. In human females, oogenesis & ovulation begins before birth: during early fetal development. Diploid oogenia numbers increase in ovaries by mitosis: during month 3. Become primary oocytes: enter meiosis i but do not complete it, arrested & remain diploid. Meiosis i is completed years later just prior to ovulation: starting at puberty, one at a time. In summary: during early fetal development in ovary follicle cells surround each developing egg cell.
