granulosa cell
Summary
Granulosa cells are somatic epithelial cells within the ovarian follicle that surround the oocyte, produce estrogen (via aromatization of androgens from theca cells), and secrete inhibin B. They proliferate under FSH stimulation and are the site of granulosa cell tumors, a sex cord-stromal ovarian neoplasm.
Detail
Granulosa cells line the follicular antrum and form the cumulus oophorus surrounding the oocyte. Under the 'two-cell, two-gonadotropin' model, LH stimulates theca interna cells to produce androgens (androstenedione, testosterone), which diffuse to granulosa cells; FSH stimulates granulosa cell aromatase, converting these androgens to estrogens (estradiol). Granulosa cells also produce inhibin B (which suppresses FSH via negative feedback) and, after ovulation, transform into granulosa lutein cells that secrete progesterone as part of the corpus luteum. Granulosa cells express FSH receptors and are essential for folliculogenesis, oocyte maturation, and formation of the zona pellucida-associated cumulus mass. Clinically, granulosa cell tumors are the most common malignant sex cord-stromal ovarian tumor, often producing excess estrogen leading to precocious puberty in prepubertal girls, or endometrial hyperplasia/postmenopausal bleeding in adults due to unopposed estrogen stimulation. Histologically, these tumors may show Call-Exner bodies (small follicles filled with eosinophilic material, mimicking primordial follicles). Elevated inhibin B and estradiol are useful tumor markers. Granulosa cell tumors are associated with increased risk of endometrial carcinoma due to chronic estrogen exposure.
Sources
- First Aid for the USMLE Step 1
- Robbins and Cotran Pathologic Basis of Disease
- Langman's Medical Embryology
- Guyton and Hall Textbook of Medical Physiology
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