What is oogenesis in females?

Oogenesis in females is the biological process that produces mature egg cells, or ova, from immature cells called oogonia.

Oogenesis is a crucial part of female reproduction, occurring in the ovaries, which are the primary reproductive organs in females. The process begins before a female is even born. During foetal development, oogonia, the cells that will eventually develop into ova, multiply by mitosis and store nutrients. By the time of birth, all oogonia have entered meiosis to become primary oocytes, but their development is paused in the first meiotic division.

At puberty, hormonal changes trigger the resumption of meiosis in one primary oocyte per menstrual cycle. The primary oocyte completes its first meiotic division to produce two cells: a secondary oocyte and a smaller polar body. The polar body typically degenerates, while the secondary oocyte enters the second meiotic division. However, this division is only completed if fertilisation occurs. If so, the secondary oocyte divides to form an ovum and another polar body, which also usually degenerates. The ovum is then ready for fertilisation by a sperm cell.

The process of oogenesis is not only responsible for producing the ova, but it also ensures that the resulting egg cells have the correct number of chromosomes (haploid), which is vital for the successful fusion of egg and sperm during fertilisation. This process is tightly regulated by a complex interplay of hormones, including follicle-stimulating hormone (FSH) and luteinising hormone (LH), which control the maturation of the oocytes and their release from the ovaries (ovulation).

In summary, oogenesis is a complex, multi-step process that ensures the production of mature, fertilisable egg cells in females. It is a fundamental aspect of female reproduction and is regulated by a variety of hormonal signals.