Granulosa cell

Micrograph of a pig oocyte surrounded by granulosa cells.

Diagram of a section through the ovary showing follicles at different stages of development.

Granulosa cells are somatic cells of the sex cord that are closely associated with the developing female gamete, the oocyte, within the ovary. These cells play a crucial role in the development and function of the ovarian follicle, as well as in the production of sex steroids.

Structure

Granulosa cells are found in the ovarian follicles, which are the basic units of female reproductive biology. Each follicle contains an oocyte, surrounded by granulosa cells and theca cells. The granulosa cells form several layers around the oocyte and are involved in the formation of the zona pellucida, a glycoprotein layer surrounding the oocyte.

Function

Granulosa cells have several important functions:

• Support of the oocyte: They provide physical support and nutrients to the developing oocyte.
• Hormone production: Granulosa cells are responsible for the production of estrogens, which are crucial for the regulation of the menstrual cycle and the development of secondary sexual characteristics.
• Follicular development: They play a role in the maturation of the ovarian follicle, which is necessary for ovulation.

Follicular Development

Granulosa cells undergo several stages of development as the follicle matures:

• Primordial follicle: In the earliest stage, granulosa cells are flat and form a single layer around the oocyte.
• Primary follicle: The granulosa cells become cuboidal and proliferate to form multiple layers.
• Secondary follicle: The granulosa cells continue to proliferate and secrete follicular fluid, forming the antrum.
• Graafian follicle: In the mature follicle, granulosa cells form the cumulus oophorus, which supports the oocyte.

Role in Ovulation

Granulosa cells are involved in the process of ovulation. They respond to the surge in luteinizing hormone (LH) by producing enzymes that break down the follicular wall, allowing the release of the oocyte.

Clinical Significance

Granulosa cells are involved in several clinical conditions:

• Granulosa cell tumor: A rare type of ovarian tumor that arises from granulosa cells.
• Polycystic ovary syndrome (PCOS): A condition characterized by an imbalance in sex hormones, affecting granulosa cell function.

Related pages

• Ovarian follicle
• Oocyte
• Estrogen
• Luteinizing hormone