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How and when are egg cells formed?

In contrast to the male, the process of meiosis of female germ cells begins between the 10th and the 13th week of fetal development, i.e., inside the mother’s womb.

Germ cells are the precursors of the female gametes (ova) and contain the genetic material that will be passed on to the next generation. Meiosis of these cells consists of two successive cell divisions, starting from a single diploid cell (also called gamete stem cell or ovogonia).

The first meiotic division of all ovogonia is completed around the 7th or 8th month of gestation, so that at the time of birth, the ovary contains primary oocytes that are in the last stage of prophase I (diplotene). Each of these oocytes is surrounded by granulosa cells, constituting primordial follicles.

From puberty onwards and throughout the reproductive maturity stage, some primordial follicles and their primary oocytes will evolve in each menstrual cycle, until they form a mature follicle and release an egg through ovulation. Thus, we see that at birth, women have all their potential reproductive cells. These are activated at puberty and are consumed throughout life, until they are exhausted, leading to the menopause.


We hope we have answered all your questions about how and when eggs are formed. However, we will be delighted to receive you to answer all your questions if you wish, by making an appointment by calling +34 932066489 or by mail, to internacional@gravidabcn.com.