Ovarian follicle

An Ovarian follicle is a fluid-filled sac that contains an immature egg, or oocyte. These follicles are found in the ovaries. Each month during a woman's menstrual cycle, an ovarian follicle releases an egg during ovulation.

Structure

The ovarian follicle is made up of several parts:

• Oocyte: The immature egg within the follicle.
• Granulosa cells: These cells surround the oocyte and produce estrogen.
• Theca cells': These cells are located outside the granulosa cells and also produce estrogen.
• Antrum: The fluid-filled space within the follicle.

Development

Ovarian follicles develop in stages:

• Primordial follicle: The earliest stage of a follicle, present at birth.
• Primary follicle: The follicle begins to grow in response to follicle-stimulating hormone (FSH).
• Secondary follicle: The follicle continues to grow and the antrum begins to form.
• Mature (Graafian) follicle: The follicle is ready to release its egg during ovulation.

Function

The main function of the ovarian follicle is to produce and release an egg for potential fertilization. The follicle also produces estrogen, which prepares the uterus for pregnancy.

Clinical significance

Problems with ovarian follicles can lead to several medical conditions, including polycystic ovary syndrome (PCOS) and infertility. Treatments for these conditions may include hormone therapy and in vitro fertilization (IVF).

See also

• Menstrual cycle
• Ovulation
• Folliculogenesis
• Ovarian reserve

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  Graafian Follicle, Human Ovary
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  Gray's Anatomy illustration of ovarian follicle
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  Human Egg
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  Human Ovarian Follicle