PARTIAL-PURIFICATION FROM BOVINE FOLLICULAR-FLUID OF A FACTOR OF LOW-MOLECULAR-MASS WITH INHIBITORY EFFECTS ON THE PROLIFERATION OF BOVINE GRANULOSA-CELLS IN-VITRO AND ON RAT FOLLICULAR DEVELOPMENT IN-VIVO

Bovine follicular fluid was aspirated from follicles of 2-20 mm in dia meter, charcoal-treated to remove steroids and then separated into low and high molecular mass fractions. The low molecular mass (< 10 kDa) fraction was purified on a Sephadex G-25 chromatography column with fo rmic acid as the eluent. Seven peaks were isolated and assayed for bio logical activity in cultures of bovine granulosa cells at concentratio ns of 10, 100 and 1000 ng ml(-1). One peak (peak 4) inhibited (P < 0.0 01) the proliferation of granulosa cells when measured by cell countin g and by [H-3]thymidine incorporation (33-37% inhibition). This peak i nhibited proliferation of granulosa cells from both small (< 2 mm) and medium (2-10 mm) follicles, but not large (> 10 mm) follicles. The in hibitory effect of peak 4 was not due to a toxic effect on cells. Admi nistration of peak 4 to rats did not affect liver or kidney masses but did decrease uterine (25%, P < 0.01) and ovarian (35%, P < 0.01) mass es. Peak 4 also caused a reduction in the number of large follicles (6 5%, P < 0.01) but increased the number of small follicles (55%, P< 0.0 1). We have named the inhibitory factor associated with peak 4, granul osa cell-inhibitory factor (GCIF). The results presented suggest that GCIF may be a factor secreted by dominant follicles that inhibits the development of: subordinate follicles.