Phase-specific changes in follistatin expression in granulosa and luteal cells documented in the present study are suggestive of a functional role for follistatin in follicular and luteal gland development in cattle. Although follistatin expression was numerically greater in the largest follicle as early as 1 day after wave emergence (i.e., D1W2), the difference among follicles did not reach significance until 3 days after wave emergence (i.e., D3W1), when dominance was clearly established. buy cipro
Dominant follicles maintained higher amounts of follistatin than their subordinate counterparts, regardless of phase, and follistatin was expressed maximally in the mid-growing and preovulatory phases. Loss of functional dominance of the wave 1 follicle, indicated by emergence of a new wave, was marked by a dramatic decrease in immunostained follistatin in the granulosa cells. After ovulation, follistatin was not visually detectable in the luteinizing cells of the follicle wall until early diestrus; and by assessment of absorptive index, maximal levels of follistatin were not expressed in luteal cells until mid-diestrus.