ANSC 3323 Lecture Notes - Lecture 4: Zona Pellucida, Artificial Vagina, Polyspermy
Document Summary
Matures right before ovulation: mature oocytes do not live very long at all, 2 pauses during oocyte development, 1st pause is at the primordial stage of development (prophase i, 2nd pause is during ovulation. Oocytes must be mature in order to create an embryo. Meiosis: 2 rounds of division instead of one, reduction in chromosomal , chromosomal pairing occurs during m1. Be able to pick out false information in steps of meiosis. Oocyte is never an individual: in a follicle, know the stages of oogenesis and follicle development (slide 7) Usually cumulus is not removed in vitro. Zona pellucida thickens in response to sperms to prevent polyspermy. Polyspermy: further sperm entry is prevented by modification of oocyte"s zona pellucida proteins and plasma membrane by contents of cortical granules. After maturation, their locations change (evenly distributed along cortex) Sperm capacitation: sperm cannot fertilize oocytes when they are freshly ejaculated.
