Granulosa cells in culture are able to produce luteinization stimulatory factor

The ability of porcine granulosa cells to release luteinization stimulator (LS) activity was studied in vitro. Granulosa cells were isolated from either small or large antral follicles of adult female pigs and were kept in culture for 1 to 5 days. The amount of LS activity in spent granulosa cell conditioned media (GCCM) was assayed in 4 days culture of small granulosa cells by the estimation of progesterone release and LH/hCC receptor induction. Granulosa cells isolated from large porcine follicles showed increased ability to release stimulatory activity in comparison with granulosa cells isolated from small follicles. The amount of LS activity did not differ markedly from day 1 to day 5 of culture and was dependent on the concentration of cultured granulosa cells. The addition of extracts prepared from granulosa cells isolated from large follicles led to a dose-related stimulation of progesterone release. However, the release of progesterone was stimulated only by low concentrations of granulosa cells extracts obtained from small porcine follicles. It is concluded that granulosa cells collected from porcine follicles possessed and retained the capacity to produce and release luteinization stimulator activity under in vitro conditions.