The aim of this study was to examine the function of granulosa cells and hormone concentrations in follicular fluid in @entity291 ovarian follicles during selection of the first dominant follicle. Ovaries were obtained from beef heifers on days 1-5 after ovulation: follicles > 4 mm in diameter were dissected and follicular fluid and granulosa cells were collected from individual follicles. @entity53 production by granulosa cells after culture with @entity251 was used to determine aromatase activity and responsiveness to gonadotrophins was determined by @entity268 production after culture with FSH or LH. Concentrations of @entity53 , @entity1420 and @entity55163 were measured in follicular fluid. Follicles were classified as largest or smaller (days 1 and 2), or dominant or subordinate (days 3-5). Aromatase activity was greater in granulosa cells from the largest follicle than in granulosa cells from smaller follicles on days 1, 3, 4 and 5 (P < 0.05). Responsiveness to LH was not detected in granulosa cells on day 1, but from day 2 to day 5 cells from the largest follicle were significantly more responsive than cells from smaller follicles (P < 0.05). Responsiveness to FSH was detected in granulosa cells from all follicles from day 1 onwards and did not differ between cells from the largest follicle or smaller follicles on any day. Follicular fluid concentrations of @entity53 and the ratio of @entity53 : @entity1420 were greater and concentrations of @entity55163 were lower in the largest follicle than in smaller follicles from day 2 to day 5 (P < 0.05). In conclusion, selection of the dominant follicle is associated with increased granulosa cell aromatase activity followed by increased @entity268 response to LH and follicular fluid @entity53 concentrations, and decreased follicular fluid concentrations of @entity55163 within 2 days after ovulation.

Gonadotrophin responsiveness, aromatase activity and insulin-like growth factor binding protein content of XXXX ovarian follicles during the first follicular wave.

@entity268 :: ('CHEBI:17489', 'Chemical') :: ['cAMP'] @entity251 :: ('MESH:D013739', 'Chemical') :: ['testosterone'] @entity55163 :: ('282262;404185', 'Gene') :: ['IGFBP-4 and -5', 'insulin-like growth factor binding proteins (IGFBPs)-4 and -5'] @entity1420 :: ('MESH:D011374', 'Chemical') :: ['progesterone'] @entity53 :: ('MESH:D004958', 'Chemical') :: ['oestradiol', 'Oestradiol'] @entity291 :: ('9913', 'Species') :: ['bovine']
@entity291 :: (9913,Species) :: ['bovine']
