A serum-free culture system for bovine granulosa cells was developed. Effects of follicle-stimulating hormone (FSH), luteinizing hormone (LH), insulin-like growth factor-I (IGF-I), and insulin-like growth factor-II (IGF-II) on steroid production by bovine granulosa cells were determined. Bovine granulosa cells from small (< 5 mm), medium (6-10 mm), and large (>10 mm) follicles were cultured for 48 h. Concentrations of estradiol-17p (E₂) and progesterone (P₄) were measured by radioimmunoassay.

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... r granulosa cells from all classes of follicles, the basal E₂ production was high during day 1 culture. With time of culture, E₂ production decreased dramatically in granulosa cells from all classes of follicles. Estradiol-17ß production increased significantly with increasing follicle size (p < 0.01). Basal P₄ production increased with the time of culture and with increasing follicle size (p < 0.01). These results indicated that a serum-free culture system can support basal granulosa cell steroidogenesis and can be used to study the effects of FSH, LH, IGF-I, and IGF-II on bovine granulosa cell steroidogenesis. Only a low dose of FSH (1 ng/ml) stimulated E 2 production by granulosa cells from medium and large follicles (p < 0.05); high doses of FSH (10, 100 ng/ml) inhibited E₂ production by granulosa cells from large follicles (p < 0.05). Follicle-stimulating hormone stimulated P₄ production from granulosa cells of all classes of follicles (p < 0.05). Luteinizing hormone inhibited E₂ production in medium and large follicles (p < 0.05). Luteinizing hormone increased P₄ production in medium and large follicles (p < 0.05). A high dose of IGF-I (100 ng/ml) increased E₂ production by granulosa cells from medium and large follicles (p < 0.05). Insulin-like growth factor-I increased P₄ production from all categories of follicles. Estradiol-170 production from large follicles decreased in response to IGF-II (10, 100, 500 ng/ml; p < 0.05). A dose of IGF-II (500 ng/ml) inhibited [...]