Question

Contrast spermatogenesis and oogenesis. what is the significance of the formation of polar bodies

Answer 1

A) Spermatogonia in the testes can undergo repeated rounds of mitosis producing more spermatogonia (2n).
Oogonia in the ovaries may either undergo repeated rounds of mitosis or enter prophase I becoming primary oocyte (2n).

b) Spermatogonium next enters the prophase I and becomes primary spermatocyte (2n).

c) Each primary spermatocyte completes meiosis I, producing two secondary spermatocytes (n).
Each primary oocyte completes meiosis I, producing a large secondary oocyte (n) and a smaller polar body which disintegrates.

d) Secondary spermatocytes undergo meiosis II and produce two haploid spermatids (n) each (total 4). Spermatids mature into sperm.
Secondary oocyte completes meiosis II producing an ovum (n) and a second polar body which also disintegrates

Significance of polar bodies: During oogenesis, the bulk of cytoplasm is collected in one egg cell which becomes the ovum and the other haploid gets very little of it and becomes polar body. The extra cytoplasm in the egg contributes to zygote development following fertilization by providing extra nutrient. Polar body analysis also allows testing the mother's genetic contribution to the embryo.