granulosacellen

Granulosacellen, or granulosa cells, are somatic cells that form the granulosa cell layer surrounding the oocyte within ovarian follicles. They originate from somatic cells in the developing gonad and proliferate during follicle growth, forming multiple layers in secondary and antral follicles and differentiating into cumulus granulosa cells that closely enclose the oocyte.

Function and hormone interactions: Granulosa cells are central to follicle development and estrogen production. They express aromatase (CYP19A1), which converts androgens produced by the theca cells into estrogens under the influence of follicle-stimulating hormone (FSH). They also secrete inhibin B, which helps regulate FSH levels, and anti-Müllerian hormone (AMH) in early-stage follicles, serving as a marker of ovarian reserve. With the LH surge that precedes ovulation, granulosa cells proliferate and eventually luteinize to form granulosa lutein cells, contributing to progesterone production in the corpus luteum.

Clinical relevance: Disorders of granulosa cells include granulosa cell tumors, part of the sex cord-stromal tumors, often associated with estrogen production and characteristic mutations such as FOXL2. AMH levels, derived from granulosa cells in growing follicles, are used clinically as an indicator of ovarian reserve and reproductive aging.

Overview: Granulosa cells collaborate with theca cells in a two-cell model of steroidogenesis, support follicle growth, mediate follicular rupture, and contribute to the endocrine changes that regulate the menstrual cycle. Their function is tightly controlled by gonadotropins and local signaling within the follicle.

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