Spermatogenesis The creation of sperm cells using mitosis

Spermatogenesis The creation of sperm cells using mitosis, meiosis, and differentiation http: //www. classjump. com/v/vicimcknight

Meiosis review Germ cell Spermatogenesis 2 n Mitosis Overview 1° spermato cytes • • 2 n Meiosis I 2° spermato cytes n 2° spermato cytes Meiosis II Spermatid n Sperm cell http: //www. classjump. com/v/vicimcknight • n • Spermatid n Sperm cell Germ cells divide by mitosis Diploid 1° spermatocytes divide by the first division of meiosis into haploid 2° spermatocytes These divide by meiosis II into haploid spermatids The spermatids mature into sperm cells (spermatozoa) by the process of differentiation – nursed by Sertoli cells.

Cross section showing the different stages http: //www. classjump. com/v/vicimcknight

Oogenesis The creation of female gametes - using mitosis, meiosis, and differentiation http: //www. classjump. com/v/vicimcknight

Oogenesis Outline Germ cells (oogonia) in the ovary divide by mitosis. 1° oocytes produced begin meiosis I – in a structure called the 1° follicle. Meiosis I is completed before ovulation and a 2° oocyte is formed (in a 2° follicle) – the polar body usually degenerates. Only after fertilisation will meiosis II be completed and a mature ovum formed by differentiation. The second polar body will degenerate http: //www. classjump. com/v/vicimcknight

Stages of Oogenesis http: //www. classjump. com/v/vicimcknight