Occurs during embryonic and fetal development ii. Completed prior to birth iii. Once an oogonium become committed to complete oogenesis it begins one of the most remarkable examples of growth of a single cell i. Preparation for post-fertilization development ii. Primary oocyte begins to grow e. The growth phase typically spans a period of several weeks to several months for most animals 3.
Mature oocyte passes through the two meiotic divisions i.
One cell retains the vast majority of the cytoplasm and becomes the egg ii. The extra sets of chromosomes are eliminated in polar bodies iii. There are two or three polar bodies formed depending on whether the first polar body divides iv. When three polar bodies are formed, each contains one copy of a haploid set of chromosomes and a small fraction of the cytoplasm from the mature oocyte v. Polar bodies are non-functional and eventually die vi. Follicle development A. Oocyte matures in close association with follicle cells 2.