Follicular atresia

Follicular atresia is a biological process that occurs in the ovaries of female mammals. It involves the breakdown and subsequent absorption of ovarian follicles, which are the basic units of female reproductive biology. Each follicle contains an immature egg cell, or oocyte, and is capable of developing into a mature egg that can be fertilized by a sperm cell. However, the vast majority of follicles never reach this stage and instead undergo follicular atresia.

Process

Follicular atresia begins when a follicle ceases to mature. This can occur at any stage of development, from the primary follicle stage to the preovulatory stage. The process is regulated by a complex interplay of hormones, including estrogen, progesterone, and follicle-stimulating hormone (FSH). When a follicle is selected for atresia, its cells begin to die in a process known as apoptosis. The follicle then shrinks and is eventually absorbed by the ovary.

Role in Reproduction

The primary role of follicular atresia is to regulate the number of eggs that a female can produce during her reproductive lifetime. Only a small fraction of the follicles present at birth will ever mature into eggs; the rest will undergo atresia. This ensures that the female's reproductive resources are not depleted too quickly. In addition, follicular atresia plays a role in the selection of the most viable eggs for ovulation.

Clinical Significance

Abnormalities in the process of follicular atresia can lead to a variety of reproductive disorders. For example, premature ovarian failure, also known as premature ovarian insufficiency, can occur when too many follicles undergo atresia too quickly. This can lead to infertility and other health problems. On the other hand, a lack of follicular atresia can lead to polycystic ovary syndrome (PCOS), a condition characterized by the presence of many immature follicles in the ovaries.

See Also

• Ovarian follicle
• Oocyte
• Apoptosis
• Premature ovarian insufficiency
• Polycystic ovary syndrome