Oogenesis

What happens during oogenesis?

Oogenesis (Greek oon = egg, genesis = origin, genesis) includes egg formation and maturation.

The formation of eggs takes place in mammals essentially prenatal, ie before birth. These ovaries (oogonia) multiply by mitosis in the ovaries. Between birth and puberty are the Ureizellen (from then on called oocytes) in a resting state. From the beginning of sexual maturity to menopause, about 500 out of approximately 40,000 oocytes enter the maturation phase. By this time, they have already survived the I Meiotic phase and consist of a haploid set of chromosomes.

At the end of the II Meiotic phase there is a haploid egg cell and three polar bodies. The peculiarity is that only one functioning, haploid oocyte is produced from an oogenesis. Already during the I Meiotic Division, there is an uneven distribution of the cell plasma. The process is repeated in the II Meiotic phase. Usually, these cells, which are useless to the body, are absorbed again. The polar bodies are helpful in artificial insemination for the diagnosis of possible incorrect distribution of the chromosome set. For if the number of chromosomes in the polar bodies is unequal, this also affects the egg to be fertilized and there is a maldistribution of the set of chromosomes (for example in trisomy 21).

Summary

The process of oogenesis involves oocyte formation and maturation

Oogenesis produces an egg cell and three polar bodies

The polar bodies are useless to the body but can be tested in artificial insemination for analysis of the oocyte chromosome set