Embryogenesis is the process by which the embryo is formed and develops. It starts with the fertilization of the ovum, egg, which, after fertilization, is then called a zygote. The zygote undergoes rapid mitotic divisions, the formation of two exact genetic replicates of the original cell, with no significant growth (a process known as cleavage) and cellular differentiation, leading to [...]
In this article we will discuss about the process of gametogenesis and fertilization in animals, explained with the help of suitable diagrams. Spermatogenesis: 1. It occurs in the testes. The walls of the seminiferous tubules of vertebrates contain primordial germ cells. 2. The primordial germ cells begin to enlarge with increased metabolism and undergo mitotic division, and produce spermatogonia. 3. [...]
In this article we will discuss about the process of gametogenesis in animals. The series of changes through which the germinal epithelial cells pass to produce germ cells or gametes is called gametogenesis (Fig. 11). The development of eggs is oogenesis and that of the sperm is spermatogenesis. The phases of development in both the gametes are essentially similar. Spermatogenesis: [...]