Cessation Of Ovulation Research Articles

224 OVARIAN FOLLICLE DEVELOPMENT DURING SEASONAL TRANSITION IN WAPITI

Wapiti are seasonally polyestrous. The transition into and out of the breeding season is marked by resumption of ovulation in autumn and cessation of ovulation in winter. Onset of ovulatory cyclicity is distinct and associated with aggressive breeding behavior of stags in rut. Cessation of ovulation at the end of the breeding season is not distinguished by behavioral patterns. The objective of the present study was to characterize follicular and luteal dynamics in wapiti during the transitional periods into and out of the breeding seasons. Transition from anestrus to estrus was monitored in 15 hinds, aged 2 to 14 years, over two successive seasons (11 in year 1, with 5 hinds from year 1 used again in year 2 along with 4 new hinds; n = 20 observations). Transition from estrus to anestrus was monitored in 11 hinds over 1 season (n = 11 observations). Hinds were maintained on a farm near Saskatoon, Saskatchewan (52°07′N, 106°38′W). The ovaries were examined daily during September through October by transrectral ultrasonography using a B-mode ultrasound machine and a 7.5 MHz linear array transducer for transition to estrus, and December through April for transition to anestrus. The first ovulation was recorded on September 15 and all hinds had ovulated for the first time by October 7. In 17 of 20 observations, the duration of the first interovulatory interval (IOI) was 9.3 ± 0.4 days (mean ± SEM). With one exception, these IOIs were characterized by one wave of follicular development. The remaining three IOIs ranged from 16 to 23 days and consisted of two or three waves of follicle development. The second ovulation occurred by October 15 in hinds with a short IOI and by October 17 in all remaining hinds. The mean dates of first and last ovulation were September 25 and February 7, respectively, an interval of 135 days. The median date of the last ovulation was February 15 and the range was from December 3 to March 22. Duration of the last IOI of the season (21.2 ± 0.6 days) was similar to the notional 21-day cycle for wapiti, but longer (P < 0.05) than the duration of the first IOI (10.9 ± 1.0 days). Maximum diameters of the first 2 ovulatory follicles were similar (11.3 ± 0.4 vs. 11.3 ± 0.2 mm), but were larger (P < 0.05) than the last 2 ovulatory follicles of the breeding season (10.3 ± 0.3 vs. 10.1 ± 0.4 mm). Maximum diameter of the corpus luteum (CL) tended (P = 0.06) to be smaller for the short IOI than for longer IOI of the first and last cycles. Diameter of the last CL of the season was not different from that of the previous CL (12.8 ± 0.6 vs. 12.5 ± 0.6 mm); however, it was detected for a longer period (22.3 ± 1.2 vs. 19.3 ± 0.7 days; P < 0.05). Estrous cycles during transition into the breeding season have been described as being irregular and those out of the breeding season as increasingly long. In the present study, the transition periods were characterized by regular events. Transition to regular estrous cycles was preceded by one short (9 days) IOI. The last IOI of the breeding season was the same as that reported during the rut. Transition to anestrus occurred most commonly in February and was marked by a failure of the dominant follicle to ovulate after luteal regression.

Circadian ovulatory rhythms in Japanese quail: role of ocular and extraocular pacemakers.

Previous studies have shown that the circadian system of Japanese quail is composed of multiple photic inputs and multiple oscillators. Among these are extraretinal photoreceptors that mediate both circadian and photoperiodic responses and circadian pacemakers in the eyes that, via neural and hormonal outputs, help to maintain rhythmicity of central circadian clocks (presumably located in the suprachiasmatic area of the hypothalamus). Furthermore, a component of the central circadian system is influenced by reproductive hormones. Under certain conditions, the circadian system of female quail can be induced to split into two circadian components: one driven by ocular pacemakers and one driven by feedback from reproductive hormones. Importantly, ovulation is either inhibited or permitted as these two oscillators (or sets of oscillators) constantly change internal phase relationships with each other, suggesting an "internal coincidence" mechanism in the control of ovulation. The oviposition patterns of quail in light-dark (LD) cycles also support an internal coincidence mechanism. The authors tested the hypothesis that the ocular pacemakers are an important component of an internal coincidence mechanism controlling ovulation by examinig the effects of blinding by complete eye removal (EX), and the effects of eye-patching, on the body temperature and oviposition patterns of quail exposed to 24-h LD cycles. They also examined the effects of EX on quail exposed to continuous light (LL) and to continuous darkness (DD). Neither EX nor eye-patching affected the oviposition patterns of birds in LD. Furthermore, robust body temperature and oviposition rhythms continued in EX birds in LL, but body temperature became arrhythmic in DD with the cessation of ovulation. The results do not show a role for ocular pacemakers in the control of ovulation, but they do support the hypotheses that (1) entrainment of the central oscillators by extraretinally perceived light is sufficient to preserve a normal ovulatory pattern in LD in the absence of the ocular pacemakers, and (2) in LL, feedback of reproductive hormones onto the central oscillators is sufficient to organize the circadian system even in the absence of the ocular pacemakers. Whether or not the ocular pacemakers are normally involved in the control of ovulation is still an open question.

An essential role for ovarian inhibin in pineal gland-mediated anestrus in Syrian hamsters.

When transferred from long photoperiod (LP) to short photoperiod (SP), female Syrian hamsters exhibit depressions of follicle stimulating hormone (FSH) and follicular development, cessation of ovulation, and marked ovarian interstitial tissue hyperplasia. Pinealectomy prevents these effects of SP. The object of this study was to determine the role of inhibin in the regulation of FSH during SP-induced anestrus. Adult LSH/SsLak hamsters maintained in LP (LD 14:10 hr) were transferred to SP (LD 8:16 hr) on the day of estrus, and groups of animals killed at either 16.00 hr on proestrus or 08.00 hr on estrus during each of five consecutive 4-day estrus cycles after transfer. Groups of females that became anestrus in SP were killed either at 08.00 or 16.00 hr, 12 days after the last observed estrus discharge. Compared to LP controls, serum FSH levels on estrus increased significantly (P<0.01) during the first two cycles in SP before declining to concentrations that were significantly lower than control values (P<0.01). Serum inhibin levels increased significantly by the third, fourth, and five days of estrus in SP. Regression analysis revealed a significant inverse correlation between serum inhibin and FSH levels on estrus during SP exposure (P=0.021) but not on proestrus. Relative levels of inhibin alpha- and betaA-subunit mRNAs were lower in ovaries from SP proestrus and anestrus females killed at 16.00 hr as compared to those from proestrus LP controls; they were elevated in ovaries from SP estrus and anestrus females killed at 08.00 hr compared to those from estrus LP controls. The absence of antral follicles on estrus in the last cycles of SP and anestrus suggests that the increase in circulating inhibin and inhibin mRNAs may be derived from hyperplastic interstitium. These observations suggest that inhibin may play an essential role in suppressing FSH secretion during pineal gland-mediated anestrus in Syrian hamsters.

Ovarian response after gonadotropin treatment of heifers immunized against gonadotropin-releasing hormone.

Angus x Hereford heifers were used to determine whether the ovaries of heifers immunized against GnRH would respond to exogenous gonadotropins. Heifers (n = 23; 24 mo; 491 +/- 23 kg) were assigned to a 2 x 2 factorial experiment: immunization against GnRH conjugated to human serum albumin (GnRH-IMM) or human serum albumin alone (HSA-IMM), and treatment with gonadotropins (GTH) or saline. The GTH treatment was 2,000 IU PMSG + 1,000 iu hCG, and control heifers were given saline (s.c.). Immunization against GnRH (GnRH-IMM) caused cessation of ovulation (progesterone < 1 ng/mL plasma for 3 wk) and GTH treatment began within 3 to 5 wk after heifers became anovulatory. Heifers immunized against HSA (HSA-IMM) were treated between d 9 and 11 of the estrous cycle. All heifers were given PGF (i.m.) on d 2 (d 0 = start of GTH treatment) and 2,000 IU of hCG (i.m.) on d 4. Ovaries of heifers were evaluated by ultrasound. Blood was sampled daily from d 0 to d 8 and every second day through d 24 to quantify progesterone and estradiol. Concentrations of estradiol increased with time after GTH but the response was reduced by GnRH-IMM (IMM x GTH x day, P < .01). Number of follicles > or = 6 mm (d 0 to 14) was increased after GTH (GTH x day, P < .001) but was decreased (P < .03) by GnRH-IMM. Immunization against GnRH reduced total follicles > or = 6 mm on d 4 in heifers on both saline and GTH treatments. Treatment with gonadotropins increased the number of follicles > or = 16 mm on d 14 compared with control heifers. The number of CL was increased by GTH (GTH x day, P < .001) but the response was reduced (P < .03) in GnRH-IMM heifers compared with HSA-IMM heifers. We conclude that treatment with gonadotropins will induce follicular growth and ovulation in heifers that are anovulatory due to immunization against GnRH.

Perimenopausal Increase in Serum Cholesterol: A 10-Year Longitudinal Study

The relative contribution of menopause to the age-related increase in serum total cholesterol concentration in women is not exactly known. Cross-sectional studies suggest a considerable contribution of menopause, whereas in short-term longitudinal studies, only a small increase was observed around menopause. In a 10-year follow-up study (1979-1989), serum total cholesterol concentration and dietary intake were measured annually in 167 healthy perimenopausal women (initially aged 49-56 years) who lived in the mixed rural/industrial community of Ede, the Netherlands. The longitudinal design enabled us to study the "natural course" of serum total cholesterol concentration and the influence of dietary fat intake during and after cessation of ovulation. For data analysis, three menopausal cohorts were created based on years relative to menopause: 2 years before ("perimenopausal"), 2 years after ("early postmenopausal"), and 6 years after ("late postmenopausal"). In each cohort, the analysis was conducted on data from 4 years of follow-up. The results show that from 2 years before to 6 years after menopause, serum total cholesterol concentration increased on average by at least 1.1 mmol/liter (19%). Thereafter, only a minor increase was observed. The rise was significantly lower in women who increased their intake of polyunsaturated fatty acids as compared with women who reduced their intake during that period. It is concluded that cessation of ovulation appears to be associated with a major increase of 19% in serum total cholesterol concentration during an 8-year period around menopause. This increase may be reduced by increasing the intake of polyunsaturated fatty acids.

Is 'Male Menopause' Real or Just an Excuse?

IT'S BECOMING popular to blame for the strange behavior of some middle-aged men during their so-called midlife crisis. Some researchers are suggesting that what they call andropause can be treated with supplemental testosterone. However, the changes that occur in men as they age have little in common with the changes that women experience when they go through menopause, says Christopher Longcope, MD, professor of obstetrics and gynecology and medicine at the University of Massachusetts Medical Center, Worchester. No Comparison The gradual decline of testosterone production in aging men, he says, does not compare with the sudden plunge in estrogen levels and the cessation of ovulation that women experience during menopause. According to Longcope, who led a luncheon round table discussion on male menopause at the recent third annual meeting of the North American Menopause Society in Cleveland, Ohio,midlife crisis in men is not a menopausal analogue.(Please see previous

Daily infusion of corticosterone and reproductive function in the domestic hen ( Gallus domesticus)

The purpose of this study was to examine the effect of the daily infusion of corticosterone on reproductive function in the laying hen and to determine the relationship between the cyclic pattern of plasma concentrations of corticosterone on the open-period for the preovulatory release of LH. An exogenous rhythm of plasma levels of corticosterone was generated using an osmotic pump. Corticosterone was infused subcutaneously into laying hens at rates of 5, 10, 15 or 30 μg/hr for a duration of 10hr beginning with the onset of darkness or at 15 μg/hr for 4hr, or continuously at 30 μg/hr. Daily infusions greater than 15 μg/hr and the continuous infusion resulted in cessation of ovulation, ovarian and oviductal regression, hyperphagia, and elevated levels of plasma corticosterone compared to that observed in control hens. The hens which were infused with 5 or 10 μg/hr of corticosterone maintained normal reproductive function with plasma concentrations of corticosterone that were approximately the same as those in the control hens. The effect of infusing 10 μg/hr of corticosterone on the open-period for the preovulatory release of LH was determined under constant light. No significant changes were observed in the frequency distribution of the times of oviposition when hens were infused with 10 μg/hr of corticosterone for 12hr from 9:00 to 21:00hr or 21:00 to 9:00hr each day. The results of this study indicate that a circadian rhythm in plasma levels of corticosterone cannot drive the open-period under constant illumination and that the effects of the infusion of corticosterone on reproductive function and feed intake are dependent upon the dose and duration of infusion.

Microscopic study of fetal hypothalamic tissue transplanted into the third ventricle of senescent female rats

As the female rat ages, her ovarian cycles become irregular and she ceases to ovulate. This aging process of reproductive function appears to be partially due to a neurodegenerative process in the hypothalamic areas responsible for the control of the anterior pituitary gland. There has been some success in recovery of function after transplantation of neural tissue in some cases of genetic neural deficits or in deficits due to lesions of the hypothalamus. This experiment was conducted to determine whether the senescent female rat will regain her ability to ovulate after fetal hypothalamic transplants. Here we describe the morphological development of the hypothalamic transplants.Basal hypothalamic or cortical (control) tissue from fetal rats at 17E were transplanted into senescent Sprague-Dawley female rats demonstrating the cessation of ovulation. Fetal tissue was mechanically dissociated and placed in artificial CSF. Ten μI aliquots of the transplant preparation were infused into the third ventricle of 6 experimental and 6 control animals with a 26 ga Hamilton syringe at a rate of 1 μl/min. The needle remained in place for 5 additional min before it was removed. Animals were monitored for vaginal cyclicity for 30 days. Cyclicity was partially restored in animals transplanted with hypothalamic but not cortical tissue.

Year and season effects on oestrus and ovarian activity in ewes of different breeds and crosses

The dates of onset and cessation of ovulation and oestrus and the duration of the ovulatory, oestrous, anovulatory and anoestrous seasons were determined for Suffolk, Rambouillet, Dorset, Finnish Landrace and reciprocal F 1 crosses between the last three breeds in a study which extended over 3 years. Ovulation rate, duration of oestrus and cycle length were also examined. Among the purebreds the major source of variation in these traits could be attributed to differences between the Rambouillet and the remaining breeds. Rambouillet ewes commenced and ceased ovarian and oestrous activity earlier than the Finn; first ovulation also occurred earlier in the Rambouillet than in the Suffolk and the duration of ovarian activity was longer for the Rambouillet than for either of these breeds. The oestrous season was 27 days shorter for the Rambouillet than for the Dorset, due to a higher incidence of ovulation without oestrus in the Rambouillet. The anoestrum was between 27 and 65 days longer for the Rambouillet than for any of the other purebreds. The period of anovulation was longest for the Suffolk breed. There was little evidence for heterosis in the duration of the breeding and non-breeding seasons. The repeatability of components of the breeding season was generally low. Ovulation rate increased slightly from early to mid-season and then declined significantly as the breeding season advanced, in all breeds.

Hormone-stimulable adenylyl cyclase and steroid concentration of follicles of the pregnant mare's serum gonadotropin-treated hen.

Pregnant mare's serum gonadotropin (PMSG) treatment of the hen disrupts the follicular hierarchy and causes cessation of ovulation. We measured serum progesterone (P4) and estradiol (E2) concentrations and follicular steroid levels and adenylyl cyclase (AC) activity of PMSG-treated hens. Serum P4 and E2 levels were elevated (P less than 0.01 and P less than 0.05, respectively) in PMSG-treated hens compared to controls. There was no significant difference in P4 and E2 concentrations in granulosa and theca layers, respectively, between follicles from PMSG-treated hens and the largest (F1) follicles from control hens. Basal, luteinizing hormone (LH)-, and follicle-stimulating hormone (FSH)-stimulable AC activity was measured in granulosa layers of the largest follicles from PMSG-treated hens and the F1 and second largest (F2) follicles from control hens. Basal AC activity was increased in follicles from PMSG-treated hens (P less than 0.05) compared to F1 control follicles. There was no difference in LH- and FSH-stimulable AC of PMSG-treated hens compared to F1 controls. Control F2 follicles had lower LH- (P less than 0.001) and FSH-stimulable (P less than 0.005) AC activity than follicles from control F1 or PMSG-treated hens. Relative LH- and FSH-stimulable AC (hormone stimulable vs. basal) for follicles from PMSG-treated hens did not differ statistically from the relative AC activity of vehicle-injected F1 or F2 follicles. Therefore, in spite of the high serum P4 and E2 levels in the PMSG-treated hens, there was no change in the hormone-stimulable AC system.(ABSTRACT TRUNCATED AT 250 WORDS)

The anovulatory hamster: a comparison of the effects of short photoperiod and daily melatonin injections on the induction and termination of ovarian acyclicity.

Cyclic female hamsters were rendered anovulatory by daily subcutaneous melatonin injections (25 microgram/0.1 ml oil) in 29 days or by transfer to a short light cycle, LD 6:18 (lights 1000-1600 hrs) in 33 days. Estrous cyclicity was reinitiated in these animals in 44 or 45 days following cessation of melatonin injections or transfer to long light cycles (LD 14:10, lights 0600-2000 hrs), respectively. Exposure of both groups to LD 6:18 after reinitiation of estrous cyclicity caused a second cessation of ovulation in 75 (melatonin group) or 61 (short light cycle group) days. Thus, although both treatments disrupted estrous cyclicity for nearly 6 weeks, this was not sufficient to induce photorefractoriness (failure to respond to short light cycles with continued estrous cyclicity). Rather, every animal responded to LD 6:18 and ceased ovulating. Melatonin-induced anovulatory hamsters showed daily gonadotropin release patterns identical to those reported in hamsters in other anovulatory states (lactating, prepubertal, and photoinduced anovulatory hamsters); that is, peak LH and FSH release at 1700 hrs daily.

Emptying of the Uterovaginal Sperm Storage Glands in the Absence of Ovulation and Oviposition in the Domestic Hen

Domestic hens were treated with pregnant mare serum to study the temporal pattern of sperm gland emptying in the absence of ovulation and oviposition. After a cessation of ovulation and oviposition, the hens were artificially inseminated with .034 ml of pooled semen. Subsequent histological examination of the uterovaginal sperm glands on days 1, 6, and 12 post-insemination indicated that the temporal rate of sperm-gland emptying was not significantly different from that of control birds which were laying normally. This observation suggests that ovulation and oviposition, along with their associated humoral factors, have a minimal effect on the emptying of the uterovaginal sperm storage glands.

Maternal age, dizygotic twinning rates and age at menopause.

The dizygotic (DZ) twinning rate declines after about maternal age 38 in Caucasian populations. Bulmer (1970) offered the explanation that waning ovarian function causes a decline in rates of double ovulation in originally twin-prone women. The present note suggests that some small part of the decline is caused by the earlier cessation of ovulation altogether in these women (presumably also as a result of waning ovarian function).

Hypothalamic regulation of gonadotropin release in female Japanese quail.

The control mechanisms of the hypothalamo-hypophysio-ovarian axis were investigated in breeding Japanese quail by means of electrolytic or radiofrequency lesions in various regions of the hypothalamus. Depending on the site of damage to the hypothalamus, two forms of ovarian dysfunction were observed. Lesions in anterior regions of the infundibular nuclear complex or in the anterior division of the median eminence resulted in regression of the ovary and oviduct; all follicles of the ovaries of these birds measured less than 3 mm in diameter. These conditions are interpreted as indicative of cessation of the release of folliclestimulating hormone from the adenohypophysis. Lesions in medial, ventral and posterior regions of the infundibular nuclear complex or in the preoptic region of the hypothalamus resulted in cessation of ovulation, but did not cause complete regression of the ovary and oviduct. In these birds the ovaries and oviducts were reduced somewhat in weight, but the ovarian follicles remained large and laden with yolk. This condition is thought to result from the cessation of the release of luteinizing hormone from the adenohypophysis.

The induction of ovulation in starving pullets using mammalian and avian gonadotropins.

Laying pullets deprived of all nourishment, except water and oyster shell grit, showed ovarian degeneration and cessation of ovulation within 72 hours. Injections of gonadotropins prevented ovarian degeneration and, in some cases, induced regular daily ovulations for 8 or more days after removal of food. With the limited range of doses investigated, intramuscular injections of dried chicken anterior pituitary glands were more effective in causing daily ovulations than was a combination of intramuscular injections of mammalian follicle stimulating hormone with intravenous injections of mammalian luteinizing hormone. There was a progressive decline in the weight of yolks ovulated by starved, hormone-supported pullets. It is suggested that failure to lay in the starved pullet is primarily due to failure of the pituitary to secrete adequate gonadotropins. The possibility that less extreme dietary deficiencies affect egg production via pituitary function is discussed briefly.

XI.—Further Observations on the Liver Clearance of Bromo-sulphthalein in the Fowl and its Relation to Œstrogen-androgen Balance

SynopsisPrevious work has shown a sex difference dependant upon œstrogen-androgen balance, in the rate of clearance by the fowl liver of intravenously administered sodium bromosulphthalein. Further observations reported here indicate an apparent rapid fluctuation of the Œ-A balance which takes place in immature chickens, both sexes snowing what is interpreted as hyperœstrogenization about the age of twelve weeks. Attention is drawn to other evidence that profound metabolic and hormonal changes occur at this stage. The effect of exogenous sex-hormones on the clearance rate of BSP has been further studied, particularly the influence of extra androgen on adult males with aberrant clearances unassociated with liver lesions. More evidence for the relation between the rate of BSP clearance and the Œ-A balance is provided by the study of the effect of cessation of ovulation on the clearance, and the effect of the development of virilizing tumours at the site of the rudimentary right ovary after left ovariectomy. Other changes which confirm hyperœstrogenization as assessed by the BSP clearance test are (a) decrease of the packed cell volume, (b) the development of a precipitable phospholipid in the plasma, (c) renal vascular changes, (d) adrenal cortical hyperplasia, (e) a frequent association with oviduct ligament “fibroids” and persistent cystic right oviducts.

Mechanism of Molting in the Hen

ABSTRACT MOLTING is associated with low laying activity or complete cessation of ovulation, a fact of both endocrinological and economical interest. It is well known that the administration of thyroid substance induces molting in any season of the year in domestic fowl (Torrey and Horning, 1922; Zavadovsky, 1925; Cole and Hutt, 1928; Van der Meulen, 1939; and others). Some investigators reported that histological examination revealed an activation of thyroidal function during molting in several species of birds, e.g. in the pigeon (Elterich, 1936), and in the canary (Takewaki and Mori, 1944). So the assumption has generally been accepted that annual molt is caused by increased thyroid activity of the birds. Sulman and Perek (1947) showed, however, that thiouracil feeding precipitated molting in the hen. Recently Shaffner (1954 Recently Shaffner (1955) and Adams (1955) reported that the administration of a large amount of progesterone induced molting outside the normal molting season. These findings throw . . .

Angina-like Pain: A Manifestation of the Male Climacterium

IN BOTH THE MALE and the female, at some period of life, a readjustment normally occurs in the body secondary to a change in the entire system of endocrine glands as a result of a lessening activity of the gonads. This change frequently takes place without distressing or untoward manifestations other than those to be expected as an integral part of the aging process. However, in a certain proportion of individuals, any of a number of unpleasant reactions may occur which are not infrequently confused with disease entities of one type or another. To such disturbances we apply the term climacterium, and in this sense it is used here. In a certain proportion of women the presence of the climacterium is generally acknowledged, perhaps because the cessation of ovulation and menstruation marks an episode in, but is not necessarily either the beginning or the end of that critical period.

Biphasic Effect of Male Sex Hormone on the Pituitary of the Female Rat

It is known that testosterone and testosterone propionate are capable of suppressing the cyclic activity of the ovaries in several species of animals.1234 Because rats which were treated with these substances presented ovaries with large corpora lutea, it was suggested that the androgenic hormones caused a release of the luteinizing principle from the anterior pituitary. This, in turn, gave rise to the persistent corpora lutea as in the diestrus of pregnancy or lactation. In monkeys and humans, on the other hand, similar treatment resulted in a cessation of ovulation and some degree of ovarian atrophy. This apparent species difference in the response to testosterone was also reflected in the uterus. The uteri of rats and rabbits developed progestation-like changes,5,6 while the uteri of the primates underwent involution.3,7It seemed to us to be significant that Hertz and Meyer,8 who used 1/10 to 1/20 of the amounts of testosterone propionate which had been employed by others to induce persistent corpora l...