Gametes are formed in the male (see testis histology) and female (see ovary histology ) gonads, by the mechanism of meiotic cell division. The generation of gametes, and their regulation, is substantially different in males and females.
In females, the total number of eggs ever to be produced are present in the newborn female.
1. In females, all eggs are arrested at an early stage of the first meiotic division as a primary oocyte. Following purberty, during each menstrual cycle, pituitary gonadotrophin stimulates completion of meiosis 1 the day before ovulation.
2. In meosis 1, a diploid cell becomes 2 haploid daughter cells. One cell becomes the secondary oocyte the other the first polar body.
3. The secondary oocyte then undergoes meiosis 2 which arrests at metaphase and will not continue without fertilization.
Ovulation releases this oocyte from the ovary.
In males, sperm continues to be generated throughout life from a stem cell population in the testis.
XY male genotype