Alterations in follicular estradiol and gonadotropin receptors during development of bovine antral follicles

Sampling follicular fluid without altering follicular status in cattle: oestradiol concentrations early in a follicular wave

“…Deviation begins when the future dominant follicle is 8.5 mm in diameter (Ginther et al, 1996), and follicular-fluid oestradiol concen¬ trations in the largest follicle are high when its mean diameter is 8-9 mm (Martin et al, 1991;Guilbault et al, 1993;Xu et al, 1995;Bodensteiner et al, 1996a (Bodensteiner et al, 1996b). Concentrations of oestradiol were evaluated with specific ELISA as previously described by Rasmussen et al (1996) and modified for direct use with follicular fluid (Bodensteiner et al, 1996b (Fig.…”

Oestrus Synchronization by PGF2α and GnRH in Intervals according to Stage of Follicular Development at Time of Initial Treatment in Cows

“…Past research showed that growing dominant follicles (greater than 10 mm in diameter) usually ovulate after GnRH treatment (Prescot et al 1992;P u rsley et al 1995;Silcox et al 1995). But GnRH is effective only in the presence of functional dominant follicle during its growing and the 1st part of the static phase (Silcox et al 1993) when follicle granulosa cells content maximum number of LH receptors (X u et al 1995;Bodensteiner et al 1996b). Diameters of this follicle are usually more than 14 mm (Savio et al 1988;Bodensteiner et al 1996a).…”

“…Diameters of this follicle are usually more than 14 mm (Savio et al 1988;Bodensteiner et al 1996a). Follicle LH receptors decrease as the dominant follicle achieves a static phase (Rolloson et al 1994;Bodensteiner et al 1996b). We hypothesized that GnRH administration would be performed in all experimental cows by the end of the growing phase or at the beginning of the static phase of the dominant follicle when GnRH would be administered 72, 48 and 24 h after PGF 2α in cows bearing small, medium and large follicles at the time of initial treatment.…”

Influence of exogenous gonadotropin-releasing hormone on ovarian function in beef cows after short- and long-term nutritionally induced anovulation1,2

“…Large follicles (~8 mm) produce and contain greater concentrations of estradiol than small follicles « 8 mm) in postpartum anovulatory cows as well as in nonnal cycling cows (Staigmiller et aI., 1982;Spicer et aI., 1986b;. Bodensteiner et al (1996) indicated that during normal estrous cycles, an increase in estradiol production by dominant follicles occurs before there is an increased in the number of gonadotropin receptors. However, differences in concentrations offollicular fluid estradiol, but not number of gonadotropin receptors in granulosa cells were associated with the early growth of dominant and subordinates follicles during the normal estrous cycle (Stewart et al, 1996).…”