Category Archives: Hormone

Circulating Concentrations of Estradiol: DISCUSSION(10)

DISCUSSION(10)

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

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Circulating Concentrations of Estradiol: DISCUSSION(9)

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

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Circulating Concentrations of Estradiol: DISCUSSION(8)

DISCUSSION(8)

The diameter of the largest follicle increased as puberty approached, probably as a result of increased numbers of LH pulses. The number of LH pulses increased between Days 0 and 2 after follicular aspiration at 5, 4, 3, 2, and 1 mo prepuberty, and this increase could have resulted in the increased rate of growth of the largest follicle compared with that at 8, 7, and 6 mo prepuberty, when the number of LH pulses did not increase between Days 0 and 2 after follicular aspiration. The number of LH pulses increased between Days 6 and 8 after follicular aspiration at 8, 7, 6, 5, and 4 mo prepuberty, but the increase in diameter of the largest follicle was of lesser magnitude than that of the largest follicle at 3, 2, and 1 mo prepuberty. The increase in the number of follicles a 5 mm 9 days after follicular aspiration indicates that a new wave of ovarian follicular growth was beginning and that the largest follicle was in the early portion of the atresia phase and therefore unresponsive to the increase in the number of LH pulses. flovent inhaler

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Circulating Concentrations of Estradiol: DISCUSSION(7)

The concentration of estradiol continued to increase between Days 5 and 7 after follicular aspiration, and this corresponded to the early portion of the growth phase of the largest follicle. buy birth control online

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Circulating Concentrations of Estradiol: DISCUSSION(6)

DISCUSSION(6)

Changes in concentrations of estradiol were subtle and must be interpreted with caution. In prepubertal female cattle, however, the hypothalamus is exquisitely sensitive to estradiol feedback inhibition of LHRH-induced LH secretion, so differences, even though subtle, may have important physiological implications. As hypothesized, the concentration of estradiol decreased over the 24 h after follicular aspiration, indicating that removal of all follicles a 4 mm in diameter decreased ovarian estrogen synthesis. However, this post-aspiration decrease in the concentration of estradiol was not acute but gradual over the 24 h after follicular aspiration.

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Circulating Concentrations of Estradiol: DISCUSSION(5)

A possible explanation of the continuous increase in the number of follicles between Days 0 and 9 after follicular aspiration was the effect that aspiration had on the number of follicles < 5 mm. Removal of follicles a 4 mm in diameter resulted in a lesser number of follicles < 5 mm on Day 1 after follicular aspiration as a result of ablating some follicles < 5 mm and removing larger follicles, which would have eventually decreased in diameter and entered the group of follicles < 5 mm in diameter as they underwent atresia. ventolin 100 mcg

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Circulating Concentrations of Estradiol: DISCUSSION(4)

DISCUSSION(4)

A pattern of ovarian follicular development and change in the concentration of FSH in 8-mo-old prepubertal cattle similar to those detected in the present study has been previously reported, with the concentration of FSH elevated 1 day before the increase in the number of subordinate follicles (a 4 mm). In postpubertal cattle, the concentration of FSH starts to increase 2-4 days before the emergence of waves of ovarian follicular development, and peaks 1 or 2 days before the emergence of those waves. The number of follicles a 5 mm and the concentration of FSH increased between 8 and 3 mo prepuberty. Because increases in concentration of FSH precede the increase in number of follicles at initiation of a new wave of ovarian follicular development in prepubertal and postpubertal cattle, it is possible that greater concentrations of FSH as puberty approached may have induced development of greater numbers of follicles a 5 mm. proventil inhaler

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Circulating Concentrations of Estradiol: DISCUSSION(3)

The concentration of FSH was elevated after aspiration of ovarian follicles and decreased between Days 0 and 5 after follicle aspiration each month prepuberty. This finding is in agreement with previous research in which unilateral ovariectomy of prepubertal cattle resulted in a transient increase in FSH, with concentrations peaking at 24 h after removal of the ovary. Cheap Diskus Advair

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Circulating Concentrations of Estradiol: DISCUSSION(2)

DISCUSSION(2)

The stage of the wave of ovarian follicular development did have a significant influence on secretion of LH, FSH, and estradiol. This indicates the intricate communication between the ovarian follicle and the hypothalamic-pituitary axis. Because the extent and type of communication to the hypothalamic-pituitary axis, via estradiol and other ovarian factors, change with stage of the wave of ovarian follicular development, evaluation of endocrine and physiological variables related to reproduction without consideration of the stage of the wave of ovarian follicular development limits the value of data obtained. Buy Advair Diskus Online

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Circulating Concentrations of Estradiol: DISCUSSION(1)

Data from the present experiment indicate that the rate of growth of the largest follicle, and the number and amplitude of LH pulses change during waves of ovarian follicular development as the peripubertal period progresses. The rate of growth of the largest ovarian follicle was greater during the selection phase of follicular development, when the number of LH pulses was greater and concentrations of estradiol were lower, than during the growth phase of follicular development. As the largest follicle grew and developed during the early growth phase of follicular development peripuberty, concentrations of estradiol increased and the number of LH pulses decreased, resulting in a decreased rate of growth of the largest follicle. During the latter portion of the growth phase, the diameter of the largest follicle increased slightly, concentrations of estradiol decreased, and the number of LH pulses increased. ampicillin antibiotic

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