FSH influences follicle

Injection of steroid-free bovine follicular fluid (bFF; 2 \m=x\5 ml s.c. 12h apart) into anoestrous ewes lowered plasma FSH concentrations by 70% and after 24 h had significantly (P < 0\m=.\01)reduced the number of non-atretic follicles (\m=ge\1 mm diam.) without influencing the total number of follicles (\m=ge\1 mm diam.) compared to untreated controls. Hourly injections of FSH (10 \g=m\gi.v. NIH-FSH-S12) for 24 h did not influence the number of non-atretic follicles but did negate the inhibitory effects of bFF on follicular viability. Hourly injections of FSH (50 \g=m\gi.v., NIH-FSH-S12) + bFF treatment for 24 h significantly increased the total number of non-atretic follicles, and particularly the number of medium to large non-atretic follicles (\m=ge\3 mm diam.) compared to the untreated controls (both P < 0\m=.\01).The 10\g=m\gFSH regimen (without bFF) significantly increased aromatase activity in granulosa cells from large ( \m=ge\5 mm diam.; P < 0\m=.\01)but not medium (3\p=n-\4\m=.\5mm diam.) or small (1\p=n-\2\m=.\5mm diam.) follicles compared to controls. The 10 \g=m\gFSH + bFF regimen had no effect on granulosa-cell aromatase activity compared to the controls. However, the 50\g=m\gFSH plus bFF regimen increased the aromatase activity of granulosa cells from large, medium and small non-atretic follicles 2\m=.\6-,8\m=.\3-and \m=ge\11-fold respectively compared to that in the control cells. Ewes (N = 11) that ovulated 2 follicles had significantly higher plasma FSH concentrations from 48 to 24 h and 24 to 0 h before the onset of a cloprostenol-induced follicular phase (both P < 0\m=.\01)than in the ewes (N = 12) that subsequently ovulated