FIBRONECTIN PRODUCTION BY CHICKEN GRANULOSA-CELLS INVITRO - EFFECT OF FOLLICULAR DEVELOPMENT

In vitro studies were conducted to investigate the role of chicken ovarian granulosa cells in the production of fibronectin, a component of the basal lamina of ovarian follicles. Collagenase dispersed granulosa cells obtained from the first (F1; about 35 mm in diameter) and third (F3; 15-20 mm in diameter) largest preovulatory follicles, as well as from a pool of small yellow follicles (SF; 6-10 mm in diameter), were incubated in serum-free medium-199 for 24 to 96 h in the absence and presence of luteinizing hormone (LH) or forskolin. Fibronectin secreted in the medium was quantitated by enzyme linked immunosorbent assay. Basal fibronectin production (which increased with the duration of incubation) was significantly greater (p < 0.001) in granulosa cells derived from mature follicle (F1) than in F3 or SF cells. Both LH and forskolin stimulated fibronectin production in SF and F3 cells in a dose-dependent manner; however, they were without effect in F1 cells. The magnitude of increase in fibronectin production elicited by LH or forskolin was greater in SF cells than in F3 cells. The cytoplasm of cultured granulosa cells taken at all stages of follicular development stained positively for fibronectin. These findings indicate that chicken granulosa cells produce fibronectin. This ability is acquired early in follicular development and the stimulatory effect of the gonadotropin (LH) diminished as the follicle approached ovulation.