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1.
The cellular proliferation and maturation of the vaginal epithelium of adult female Vervet monkeys was examined during their menstrual cycles. At the same time the serum contents of estrogen and progesterone were analysed. Gradual but distinct patterns demarcated the phases of the menstrual cycle cytologically. The karyopyknotic index paralleled the estrogen concentration. Mid-cycle peak maturation produced many anucleate squames, which exfoliated, forming a diagnostic vaginal discharge. 相似文献
2.
Female golden hamsters exposed to short photoperiods become anestrous and exhibit daily surges of gonadotropins and progesterone. Since little is known about the transition between the cycling and anovulatory states, the following experiments were done to determine whether there are hormonal changes that precede cessation of estrous cyclicity. Females killed on the morning of estrus, up to the tenth estrous cycle in short days, showed no hormonal or ovarian morphologic evidence of changes in reproductive function. When assessed on the afternoon of estrus, however, serum levels of luteinizing hormone and progesterone increased significantly before vaginal and ovarian cyclicity ceased. Females sampled in both the morning and afternoon at increasing durations since their last vaginal estrus revealed that maximal daily surges of both gonadotropins and progesterone were not consistently manifested until the vaginal cycle had been absent for 2 weeks. By then, estrogen levels and uterine weights were low and ovaries showed hypertrophied interstitia and arrested follicular growth. We have demonstrated that there are hormonal changes in females before the loss of the vaginal cycle and onset of major daily hormonal surges. Our results suggest that alterations in feedback relationships between steroid hormones and gonadotropins may precede photoperiod-induced anestrus. 相似文献
3.
We determined changes in plasma hormone concentrations in gilts after treatment with a progesterone agonist, Altrenogest (AT), and determined the effect of exogenous gonadotropins on ovulation and plasma hormone concentrations during AT treatment. Twenty-nine cyclic gilts were fed 20 mg of AT/(day X gilt) once daily for 15 days starting on Days 10 to 14 of their estrous cycle. The 16th day after starting AT was designated Day 1. In Experiment 1, the preovulatory luteinizing hormone (LH) surge occurred 5.6 days after cessation of AT feeding. Plasma follicle-stimulating hormone (FSH) increased simultaneously with the LH surge and then increased further to a maximum 2 to 3 days later. In Experiment 2, each of 23 gilts was assigned to one of the following treatment groups: 1) no additional AT or injections, n = 4; 2) no additional AT, 1200 IU of pregnant mare's serum gonadotropin (PMSG) on Day 1, n = 4); 3) AT continued through Day 10 and PMSG on Day 1, n = 5, 4) AT continued through Day 10, PMSG on Day 1, and 500 IU of human chorionic gonadotropin (hCG) on Day 5, n = 5; or 5) AT continued through Day 10 and no injections, n = 5. Gilts were bled once daily on Days 1-3 and 9-11, bled twice daily on Days 4-8, and killed on Day 11 to recover ovaries. Termination of AT feeding or injection of PMSG increased plasma estrogen and decreased plasma FSH between Day 1 and Day 4; plasma estrogen profiles did not differ significantly among groups after injection of PMSG (Groups 2-4). Feeding AT blocked estrus, the LH surge, and ovulation after injection of PMSG (Group 3); hCG on Day 5 following PMSG on Day 1 caused ovulation (Group 4). Although AT did not block the action of PMSG and hCG at the ovary, AT did block the mechanisms by which estrogen triggers the preovulatory LH surge and estrus. 相似文献
4.
The role of gonadotropins and estrogen on the regulation of ovarian ornithine decarboxylase was studied during follicular
differentiation/maturation. In intact immature rats follicular differentiation/maturation was initiated with sequential administration
of estrogen and follicle stimulating hormone. Ornithine decarboxylase activity in response to human chorionic gonadotropin
was markedly enhanced (2-fold) in rats with preovulatory antral follicles when compared to rats with non-ovulatory follicles.
This increase could be attributed to the alteration in the turnover of the enzyme. Following follicle maturation the half
life of the human chorionic gonadotropin stimulated ornithine decarboxylase was increased from 18 to 62 min. This increase
in half life was associated with differentition of follicles. In the estrogen treated group (which does not induce follicular
differentiation), the half life of the enzyme remained unaltered. The regulation of ornithine decarboxylase through the formation
of protein inhibitor antizyme induced by diamino hexane, was unaltered during follicular differentiation. 相似文献
5.
The primary objective of this study was measurement of the systemic bioavailability of DHEA and its metabolites following daily intravaginal application of the sex steroid precursor. Forty postmenopausal women were randomized to receive a daily dose of one ovule of the following DHEA concentrations: 0.0%, 0.5%, 1.0% or 1.8%. After only 7 days of treatment, the maturation value of the vaginal epithelial cells was significantly increased while the vaginal pH was significantly decreased at all DHEA doses. These important local effects were observed while the serum concentrations of estradiol and testosterone remained within the values found in normal postmenopausal women at all DHEA doses. Similar observations were made for serum androstenedione, estrone, estrone-sulfate and DHEA-sulfate. Even at the highest 1.8% DHEA dose, serum DHEA was increased at the levels found in normal premenopausal women. The present data show that the intravaginal administration of DHEA permits to rapidly achieve the local beneficial effects against vaginal atrophy without significant changes in serum estrogens, thus avoiding the increased risk of breast cancer associated with the current intravaginal or systemic estrogenic formulations. In addition, the recent observation that DHEA is transformed into both androgens and estrogens in the vagina permits to exert benefits on all the three layers of the vaginal wall. 相似文献
6.
In the female hamster, a daily rhythm of gonadotropin release begins almost 3 weeks prior to the initiation of 4-day estrous cycles. A temporal relationship exists between the onset of this cyclic release of gonadotropin and age at puberty. We hypothesized that since opiate agonists depress circulating gonadotropins and antagonists increase them in both adult and immature rodents, endogenous opiates may influence the mechanism controlling cyclical gonadotropin release in the prepubertal female hamster and thus affect rate of sexual maturation and hence the age at puberty. This proposal was tested by chronic administration of naloxone (NAL), an opiate receptor antagonist. We predicted that NAL might induce the early initiation of daily surges of luteinizing hormone (LH) if endogenous opiates inhibit sexual maturation. Naloxone was injected daily (50 mg/kg body wt) at about 1300 hr from Days 1 through 17 of age. The NAL injections increased serum LH and significantly advanced the age at which first estrus vaginal discharge was observed (32 vs 38 days for saline-injected controls in Experiment I and 31 vs 37 days in Experiment II). However, the NAL injections did not correspondingly advance the age of initiation of endogenously generated daily cycles of circulating LH. We conclude that blockade of opiate receptors accelerates sexual maturation by directly inducing the release of LH and not by advancing the age of initiation of endogenous gonadotropin surges. 相似文献
7.
Estrogens have an essential role in the regulation of bone maturation and importantly in the closure of growth plates in both sexes. This prospective, randomized, placebo-controlled study was undertaken to evaluate whether suppression of estrogen synthesis in pubertal boys delays bone maturation and ultimately results in increased adult height. A total of 23 boys with constitutional delay of puberty (CDP) received a conventional, low-dose testosterone treatment for inducing progression of puberty. Eleven of these 23 boys were randomized to receive a specific and potent P450-aromatase inhibitor, letrozole, for suppression of estrogen action, and 12 boys were randomized to receive placebo. Estradiol concentrations in the letrozole-treated boys remained at the pretreatment level during the administration of letrozole, whereas the concentrations increased during the treatment with testosterone alone and during spontaneous progression of puberty. Testosterone concentrations increased in all groups, but during the letrozole treatment, the increase was more than fivefold higher than in the group treated with testosterone alone. The inhibition of estrogen synthesis delayed bone maturation. The slower bone maturation in the boys treated with testosterone and letrozole, despite higher androgen concentrations, than in the boys treated with testosterone indicate that estrogens are more important than androgens in regulation of bone maturation in pubertal boys. During the 18 months follow-up, an increase of 5.1 cm in predicted adult height was observed in the boys who received testosterone and letrozole, but no change was seen in the boys who received testosterone alone or in the untreated boys. This finding indicates that an increase in adult height can be attained in growing adolescent boys by inhibiting of estrogen action. 相似文献
8.
The pattern of GnRH-like stimuli capable of inducing follicular growth, ovulation, and luteal function was evaluated in ewes passively immunized against GnRH. The estrous cycles of 30 regularly cyclic sheep were synchronized using vaginal pessaries impregnated with a synthetic progestogen. Animals were passively immunized against GnRH (groups 2-5, n = 6) or the carrier protein, keyhole limpet hemocyanin (KLH; group 1, n = 6), at the time of pessary removal (PR). Circhoral delivery of saline (groups 1, 2, and 5) or low amplitude GnRH agonist (des-Gly10 GnRH ethylamide [100 ng/hourly pulse]; groups 3 and 4) was initiated at PR and continued for 3 (groups 4 and 5) or 12 days (groups 1-3). In groups 4 and 5, the amplitude of the GnRH-like stimulus was increased to 800 ng/hourly pulse (stimulus-shift) during the 24-h period beginning 72 h after PR. The amplitude of the hourly stimulus was adjusted to 100 ng/pulse 96 h after PR and continued at that level to Day 12. The endocrine changes associated with follicle growth and maturation (serum concentrations of estradiol [E2] above 10 pg/ml), ovulation (surge-like secretion of LH and FSH), and normal luteal function (serum concentrations of progesterone [P] above 2 ng/ml) were evident in ewes passively immunized against KLH (group 1). In this group, the preovulatory surge of gonadotropins was noted 48.7 +/- 1.2 h after PR. These endocrine events were blocked by passive immunization against GnRH (group 2).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
9.
The influence of estrous cow serum (ECS) or fetal calf serum (FCS) and their interaction with gonadotropins on in vitro bovine maturation and fertilization was evaluated. The addition of ECS or FCS to the medium significantly increased the percentage of oocyte maturation over that of Ham's F-10 medium alone (P<0.05). The addition of follicle stimulating hormone (FSH), human chorionic gonadotropin (hCG) or of FSH plus hCG to the medium provided no advantage in maturation over serum alone. However, FSH plus HCG added to the maturation medium significantly improved the frequency of pronucleus formation in both groups compared with a medium to which no gonadotropins were added (P<0.05). Both ECS and FCS (as medium supplements) promoted oocyte maturation. Although the addition of a combination of FSH plus hCG to the medium did not increase the rate of oocyte maturation, it did contribute to the high incidence of subsequent pronucleus formation. 相似文献
10.
Electrochemical stimulation of the hypothalamus of 23-day-old female rats induced precocious puberty as judged by occurrence of vaginal opening, the degree of uterine hypertrophy, changes in ovarian steroid content and incidence of first ovulation. Three types of responses were observed: (I) pubertal ovulation within 96 h; (II) pubertal ovulation within 120 h, and (III) vaginal opening at 120 h not followed by ovulation. All treated animals showed a sustained increase in the LH/FSH ratio in both pituitary and plasma. Plasma estrogen was also increased 1 h after stimulation. A preovulatory rise in plasma estrogen and gonadotropins was noted in type I and type II animals. These data lend further support to the suggestion that brain stimulation causes a release of gonadotrophins which induced ovarian steroidogenesis leading to an ovulatory gonadotropin surge via a positive feedback effect. 相似文献
11.
In a series of experiments the development of sexual behavior was studied in female rats. Lordosis behavior in response to manual stimulation was induced in 100% of 19-day old females by treatment with 10 μgm estradiol benzoate (EB) and 0.5 mgm progesterone (P) and earwiggling was displayed at earlier ages. During normal development, vaginal opening preceded the display of the first receptivity in most cases, the first two behavioral sex cycles tended to be prolonged and irregular, but the subsequent cycles were of regular 4 or 5 days duration. Although treatment of immature (18-, 23- or 28-day old) females with EB (10 μgm) and P (0.5 mgm) or with EB (0.025, 0.25 or 2.5 μgm until vaginal opening occurred) resulted in precocious vaginal opening and display of sexual receptivity, the treatment did not advance the development of behavioral cyclicity. Progesterone [0.25 mgm/100 gm body weight (bw)] facilitated the display of sexual receptivity in EB-primed (0.5 or 2.5 μgm/100 gm bw) ovariectomized immature and adult female rats. Evidence was presented that behavioral sensitivity to estrogen increases with age. 相似文献
12.
Recent studies suggest that bone marrow stem cells (BMSCs) are promising grafts to treat a variety of diseases, including reproductive dysfunction. Primary ovarian failure is characterized by amenorrhea and infertility in a normal karyotype female, with an elevated serum level of follicle-stimulating hormone (FSH) and a decrease level of estrogen caused by a mutation in FSH receptor (FSHR) gene. Currently, there is no effective treatment for this condition. The phenotype of FSHR (-/-) mouse, FORKO (follitropin receptor knockout), is a suitable model to study ovarian failure in humans. Female FORKO mice have elevated FSH, decreased estrogen levels, are sterile because of the absence of folliculogenesis, and display thin uteri and small nonfunctional ovaries. In this study, we determined the effects of BMSC transplantation on reproductive physiology in this animal model. Twenty four hours post BMSC transplantation, treated animals showed detectable estroidogeneic changes in daily vaginal smear. Significant increase in total body weight and reproductive organs was observed in treated animals. Hemotoxylin and eosin (H&E) evaluation of the ovaries demonstrated significant increase in both the maturation and the total number of the follicles in treated animals. The FSH dropped to 40-50% and estrogen increased 4-5.5 times in the serum of treated animals compared to controls. The FSHR mRNA was detected in the ovaries of treated animals. Our results show that intravenously injected BMSCs were able to reach the ovaries of FORKO mice, differentiate and express FHSR gene, make FSHR responsive to FSH, resume estrogen hormone production, and restore folliculogenesis. 相似文献
13.
This study aimed to elucidate the mechanisms that may lead to an efficient strategy to induce a suitable host response of the vaginal mucosa upon exposure to intravaginally delivered exogenous compounds. It was hypothesized that the upregulation of intercellular adhesion molecule (ICAM)-1 gene expression may reflect the inflammatory response evoked by exogenous compounds. Major emphasis was placed on ethylenediamine tetraacetic acid (EDTA) which was added as a synergistic agent to conventional spermicidal agents or anti-HIV drugs. The levels of ICAM-1 mRNA were examined as a surrogate marker for inflammatory response in human vaginal epithelial cells upon exposure to EDTA or interleukin (IL)-1β (i.e. positive control, 25 mM). The effects of estrogen on EDTA-induced ICAM-1 expression were also evaluated for the estrogen involvement in the inflammatory process of the vaginal mucosa. ICAM-1 expression in human vaginal cells (VK2/E6E7 cells) increased as EDTA concentration added to human vaginal cell lines increased. The effects of estrogen on EDTA-induced ICAM-1 expression in human vaginal epithelial cells were estrogen-concentration dependent; estrogen at lower concentrations (~1–10 nM) did not affect ICAM-1 expression, whereas estrogen at higher concentrations (~100 nM–1 µM) attenuated ICAM-1 expression. The influence of estrogen in ICAM-1 expression suggests the beneficial effects of estrogen on the regulation of vaginal homeostasis. Identification and quantification of specific surrogate markers for the inflammatory response evoked by exogenous compounds and their regulation by estrogen will lead to an efficient strategy against sexually transmitted diseases including AIDS. 相似文献
14.
This study aimed to elucidate the mechanisms that may lead to an efficient strategy to induce a suitable host response of the vaginal mucosa upon exposure to intravaginally delivered exogenous compounds. It was hypothesized that the upregulation of intercellular adhesion molecule (ICAM)-1 gene expression may reflect the inflammatory response evoked by exogenous compounds. Major emphasis was placed on ethylenediamine tetraacetic acid (EDTA) which was added as a synergistic agent to conventional spermicidal agents or anti-HIV drugs. The levels of ICAM-1 mRNA were examined as a surrogate marker for inflammatory response in human vaginal epithelial cells upon exposure to EDTA or interleukin (IL)-1β (i.e. positive control, 25 mM). The effects of estrogen on EDTA-induced ICAM-1 expression were also evaluated for the estrogen involvement in the inflammatory process of the vaginal mucosa. ICAM-1 expression in human vaginal cells (VK2/E6E7 cells) increased as EDTA concentration added to human vaginal cell lines increased. The effects of estrogen on EDTA-induced ICAM-1 expression in human vaginal epithelial cells were estrogen-concentration dependent; estrogen at lower concentrations (∼1-10 nM) did not affect ICAM-1 expression, whereas estrogen at higher concentrations (∼100 nM-1 µM) attenuated ICAM-1 expression. The influence of estrogen in ICAM-1 expression suggests the beneficial effects of estrogen on the regulation of vaginal homeostasis. Identification and quantification of specific surrogate markers for the inflammatory response evoked by exogenous compounds and their regulation by estrogen will lead to an efficient strategy against sexually transmitted diseases including AIDS. 相似文献
15.
Bone morphogenetic protein (BMP) 15 and growth differentiation factor (GDF) 9 are oocyte-secreted growth factors that are critical local regulators of ovarian function and may be involved in preovulatory cumulus expansion. As cumulus expansion occurs in response to the ovulatory surge, the present study was designed: 1) to investigate whether GDF9 and BMP15 are regulated by gonadotropins in the mouse ovary; and 2) to visualize changes in both GDF9 and BMP15 immunostaining in response to gonadotropins. Immature 21-day-old mice were sequentially treated with recombinant human FSH (r-hFSH), 5 IU daily, at Days 21, 22, and 23 of life, then injected with 5 IU hCG at Day 24 of life. In response to r-hFSH, steady-state Bmp15 mRNA expression levels increased in both total ovaries and cumulus-oocyte complexes, whereas Gdf 9 mRNA levels did not. In addition, BMP15 protein levels increased in total ovaries. The GDF9 immunostaining was exclusively seen in growing oocytes in both control and gonadotropin-treated mice, whereas that of BMP15, which was also primarily seen in growing oocytes, exhibited important changes in response to gonadotropins. Strong BMP15 immunostaining was observed in the follicular fluid of atretic antral follicles after FSH treatment and in expanded, but not in compact, cumulus cells after hCG. The present results show for the first time that BMP15 levels increase during gonadotropin-induced follicular development, in parallel with oocyte maturation, and that this local factor is likely involved in cumulus expansion as previously suggested by studies in Bmp15-null mice. 相似文献
16.
The effects of five different gonadotropins and homologous pituitary homogenate (HP) on germinal vesicle breakdown (GVBD) were investigated in vitro using folliculated oocytes of Clarias batrachus. Among all the gonadotropins, salmon gonadotropin (SG-G100) was the most potent in vitro inducer of oocyte maturation. At concentrations of 1, 0.1, 0.01 and 0.001 microgram/ml it induced 86.98 +/- 2.71, 68.74 +/- 2.85, 44.56 +/- 1.75 and 25.90 +/- 2.36% GVBD. Next to SG-G100 in inducing GVBD was luteinizing hormone (LH) which was consistently found to be effective at all the concentrations used. Human chorionic gonadotropin was also found to be effective at all the concentrations but when compared to SG-G100 and LH, it was less effective. Follicle stimulating hormone and pregnant mare serum gonadotropin were found to be effective at higher concentrations but were ineffective at the lowest concentration. HP treatment resulted in a significant number of GVBD at all the three concentrations used. 相似文献
17.
The objectives were to determine the effects of (i) time during the first FSH increase of the estrous cycle (time-course study) and (ii) exogenous steroid treatment (steroid feedback study) on the relationship between circulating serum gonadotropins, and the proportions of pituitary cells immunoreactive for gonadotropins and steroid receptors during the estrous cycle in heifers. Pituitaries were collected from heifers (n=40) slaughtered at 13h (n=8), 30h (n=24) and 66h (n=8) after estrous onset, corresponding to before, during and after the first FSH increase of the estrous cycle. Heifers slaughtered during the FSH increase (at 30h) either received no treatment (n=8), or were treated (n=16) with estradiol benzoate and/or progesterone before slaughter. During the time-course study, the proportion of pituitary cells immunoreactive for FSH increased (P<0.05) during the first transient FSH increase reflecting serum concentrations. The proportion of pituitary cells immunoreactive for LH was unaltered, a reflection of serum LH concentrations. The proportion of estrogen receptors (ER)-alpha, but not ER-beta, was decreased (P<0.05) at 30h compared with at either 13 or 66h. During the steroid feedback study, exogenous progesterone with or without estradiol suppressed (P<0.05) the proportions of pituitary cells immunoreactive for gonadotropins, serum FSH concentrations and LH pulse frequency. Steroid treatment did not alter the proportion of pituitary cells positive for estrogen receptors (alpha and beta). While progesterone receptors (PR) were not detected in the anterior pituitary by immunohistochemistry during the early estrous cycle or in response to steroid treatment, quantitative real-time PCR revealed that mRNA for progesterone receptors was expressed at very low levels. The expression of pituitary PR mRNA was decreased (P<0.05) at 30 and 66h compared with 13h, and was suppressed (P<0.05) following steroid treatments. Alterations in pituitary steroid receptors are implicated in the differential regulation of gonadotropin secretion during the first transient FSH rise, but not in response to exogenous steroids. The time-course study and steroid feedback responses support the hypothesis that LH pulse frequency is tightly linked to regulation of GnRH pulse frequency. Serum FSH is regulated by its own synthesis, as reflected by pituitary FSH content and perhaps by alterations in pituitary sensitivity to circulating steroids by changes in steroid receptor content. 相似文献
18.
Boars have high concentrations of plasma and testicular estrogens, but how this hormone is involved in feedback regulation of the gonadotropins and local regulation of testicular hormone production is unclear. The present study examined the effects of reducing endogenous estrogens by aromatase inhibition on concentrations of plasma LH and FSH and on testicular and plasma concentrations of testosterone (T) and immunoreactive inhibin (INH). Thirty-six littermate pairs of boars were used. One boar from each pair was assigned to the control group (vehicle); the other boar to the treatment group (aromatase enzyme inhibitor, Letrozole, 0.1 mg/kg body weight [BW]). Weekly oral treatment started at 1 wk of age and continued until castration at 2, 3, 4, 5, 6, 7, or 8 mo. Plasma concentrations of gonadotropins, INH, T, estradiol (E2), and estrogen conjugates (ECs) were determined. Testicular tissue was collected at castration for determination of INH and T and for confirmation of reduced aromatase activity. The acute effects of aromatase inhibition on gonadotropins were monitored in two adult boars treated once with Letrozole (0.1 mg/kg BW). Treatment with the aromatase inhibitor reduced testicular aromatase activity by 90% and decreased E2 and ECs without changing acute, long-term, or postcastration LH and FSH. Plasma T, testicular T, and circulating INH concentrations did not change. Testicular INH was elevated in treated boars compared with controls. In conclusion, estrogen does not appear to play a regulatory role on gonadotropin secretion in the developing boar. This is in direct contrast to findings in males of several other species. 相似文献
19.
Failure of daily injections of ketamine hydrogen chloride (HCL) to adversely alter menstrual cycle length, blood estorgen, and progesterone levels in the rhesus monkey is reported. The study was carried out with 30 adult female monkeys to determine the effects of daily administration of 8-10 mg ketamine HCL/kg. In physically restrained control monkeys there were 14 of 25 ovulatory cycles and inketamine-treated monkeys there were 28 of 32 ovulatory cycles. Menstrual cycle length was the same in both groups. The levels and time course of estrogen and progesterone levels were the same in the ovulatory cycles of both groups. In 30% of the control cycles and in 25% of the ketamine-treated there were luteal phases in which the preovulatory estrogen levels were normal and in which the luteal-phase progesterone levels were low and variable 6-8 days after the preovulatory surge. It is concluded that the daily use of ketamine HCL does not markedly alter menstrual cycle length, or serum estrogen or progesterone levels throughout the menstrual cycle. The incidence of anovulatory cycles and premature menstrual induction was reduced probably by reducing the stress of restraining the monkey for the purpose of taking a blood sample. 相似文献
20.
The objective of this experiment was to assess the relationship between electrical resistance of the vaginal mucosa and serum concentrations of estradiol (E2) and progesterone (P4) during the estrous cycle in ewes. Vaginal impedance was recorded daily using a 2-electrode impedometer in 10 nonprolific Western white-faced and 7 prolific Finn ewes, during the mid-breeding season (October to December). Transrectal ultrasonography of ovaries was performed once a day to confirm ovulation and monitor follicle growth (follicles > or =3 mm in diameter) and development of corpora lutea (CL). Jugular blood samples were collected daily for radioimmunoassay (RIA) of estradiol and progesterone. In all ewes, a decline in vaginal impedance (to <40 ohms) was closely associated with the onset of behavioral estrus. In both breeds of sheep, there was no significant correlation between daily serum concentrations of estradiol and vaginal impedance throughout the estrous cycle. Daily serum concentrations of progesterone and the E2:P4 ratio were correlated with vaginal impedance during the period of luteolysis and follicular phase in both breeds (Western white-faced ewes: r = 0.62, P = 0.0002 and r = -0.56, P = 0.0002; Finn ewes: r = 0.61, P = 0.001 and r = -0.45, P = 0.03, respectively) and early in the cycle (Days 0 to 2, Day 0 = day of ovulation) in white-faced ewes (r = 0.61, P = 0.0003 and r = -0.36, P = 0.052, respectively) but not during the remaining portion of the luteal phase in either breed. In conclusion, vaginal mucous impedance appears to be primarily controlled by progesterone, but it also changes in response to shifts in the E2:P4 ratio when progesterone concentrations are low. Impedometric characteristics of the vaginal mucosa in cyclic ewes are an indicator of serum concentrations of progesterone and E2:P4 ratios during the terminal stage of the estrous cycle. 相似文献
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