During the wave of ovarian follicular development, the concentration of FSH exhibited changes similar to the pattern observed during waves of ovarian follicular growth in postpubertal females. The concentration of FSH increased as puberty approached, with this increase corresponding to an increase in the number of follicles a 5 mm. The number of LH pulses was greater during the selection phase of development of the largest follicle, when concentrations of estradiol were lower, than during the early and latest portion of the growth phase, when concentrations of estradiol were higher. buy ventolin inhalers
As puberty approached, the number of LH pulses and the concentration of estradiol increased during the wave of ovarian follicular development, indicating decreased negative feedback of estradiol on secretion of LH. This increase in the number of LH pulses corresponded to an increased growth rate of the largest follicle, which ultimately attained a size of approximately 13 mm in the month preceding ovulation. In a previous study with cattle, when the largest follicle attained a size of 13 mm, the pubertal ovulation ensued. The most important finding in the present experiment supports our hypothesis that the release of ovarian factors such as estradiol and the regulation by these factors of release of LH and FSH during waves of ovarian follicular development change with the transition from prepuberty to puberty. On the basis of the present and previous research, we hypothesize that the increased release of LH pulses during waves of ovarian follicular development during the last 3 mo prepuberty results in development of ovarian follicles of greater diameter, which ultimately reach sizes of about 13 mm and produce enough estradiol to induce the preovulatory surge of gonadotropins and the behavioral estrus at puberty.