Spermatogenesis results in 4 sperm; oogenesis results in only 1 egg.

Spermatogenesis results in only 1 sperm; oogenesis results in 4 eggs.

Spermatogenesis results in 2 sperm; oogenesis results in only 1 egg.

Spermatogenesis results in 8 sperm; oogenesis results in only 4 eggs.

Spermatogenesis results in only 1 sperm; oogenesis results in 2 eggs.

64 days

2 weeks

72 hours

25 weeks

7 months

Metaphase II

Metaphase I

Prophase II

Prophase I

Anaphase I

An oogenetic ‘stasis’ between embryo and puberty

A meiosis stabilizing factor

The primordial follicle

The state between fertilization and the start of gonadotropin production

Pre-vitellegenic stage in fetal development