It is possible that the varying concentrations of estradiol during the selection, growth, and atresia phases of the largest follicle may have an effect in regulating the number of LH pulses in prepubertal female cattle that is similar to the effect of progesterone in postpubertal female cattle, because estradiol is the primary regulator of the number of LH pulses during the prepubertal period in female cattle. There was a prepubertal decline in negative feedback of estradiol on secretion of LH in ovariectomized prepubertal cattle administered estradiol implants during the period when age-matched intact female cattle attained puberty. After this period, the ovariectomized females treated with estradiol had greater amounts of LH in circulation because of an enhanced amplitude of LH pulses. These data support the hypothesis that estradiol is the primary regulator of the number of LH pulses during waves of ovarian follicular development, with the inhibitory effect of estradiol on the frequency of LH pulses decreasing as puberty approaches. buy cipro
In conclusion, concentrations of estradiol, FSH, and LH, and the number of LH pulses changed during the wave of ovarian follicular development as puberty approached. This supported our hypothesis that ovarian follicles of prepubertal female cattle release factors in the blood, particularly estradiol, in varying amounts during waves of ovarian follicular development that regulate release of LH and FSH in a dynamic fashion as the wave of follicular development progresses.