What are the stages of oogenesis?
Once the germ cell becomes matured and differentiated to enter meiosis, it is called a primary oocyte.
- Primary oocyte undergoes first meiotic division (which is reductional division) and a secondary oocyte is formed along with a polar body. Former is functionally not viable.
- Secondary oocyte divides by second meiotic division (which is like mitotic division) and a functional ovum is generated along with another polar body.
The cytoplasm of the oocyte is conserved during both the cytokinesis, hence despite getting one half of the genetic material, the first polar body receives minimal cytoplasm after first meiotic division. Same thing happens after second meiotic division and a second polar body is formed.
In case of oogenesis only one functional gamete is formed compared to male's spermatogenesis where each meiotic division gives rise to four functional gametes.