Oogenesis in mammals

Published on June 30, 2019   55 min

Other Talks in the Series: The Female Reproductive System: from Basic Science to Fertility Treatments

Hello, my name is Hugh Clarke. I'm a professor at McGill University, and I'm going to talk to you today about "Oogenesis in Mammals". The process of oogenesis in mammals actually begins before birth. I'm going to talk to you about the process of oogenesis afterbirth. Before I do so I'll just say a little bit about what happens before birth.
Before birth, the female germ cells which are known as oogonia proliferate to generate a large starting population of oogonia cells. Then, again before birth these oogonia, enter into the mitotic phase of the cell cycle. At this stage we call them oocytes. So these oocytes, which are now in meiosis begin the process of recombination, and they progress as far as diplotene of the meiotic cell cycle. At this point, they become arrested. So this is before the birth of the female, and they'll remain arrested at diplotene until the time of ovulation, which could be many months or in the case of women many years later. By the time of birth or shortly after birth, all of the oocytes have been assembled into what we call primordial follicles. Each primordial follicle consists of one oocyte surrounded by a small number of somatic follicular cells that will term granulosa cells. So this means that at the time of birth or shortly after birth, the ovary of the female is populated by thousands or hundreds of thousands of primordial follicles. Before I explain to you the process of oocyte development after birth, I just want to say a few words about what happens to oocytes before birth or female germ cells before birth.