Follicular fluid stimulation of steroidogenesis in immature granulosa cells in vitro.

Abstract Granulosa cells from small (1–2 mm) immature porcine follicles were cultured in monolayer in culture media composed of equal parts of culture medium 199 and either (a) fluid from small follicles, (b) fluid from large (6–12 mm) follicles or (c) adult female porcine serum for 6 days, with or without 100ng LH and/or 2 μg FSH/ml. Both basal and gonadotrophinstimulated progesterone secretion were greater in the presence of fluid from large follicles than in serum, for all 6 days. After 4 days of culture, fluid from small follicles enhanced gonadotrophin-stimulated progesterone secretion over that occurring in serum, but to a lesser extent than fluid from large follicles. These studies suggest the presence of a maturation stimulating molecule(s) in follicular fluid which increases in activity or concentration as the follicles enlarge. This factor may be essential for normal granulosa cell maturation in vivo.