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International audience; The objective of this review is to describe how dietary glucogenic precursors could stimulate ovarian activity in post-partum dairy cows and improve reproductive success. Although the nutrient requirements for the early resumption of ovarian cycles, and for follicle and embryo development are quantitatively small, reproductive success is deteriorated by post-partum negative energy balance. Since very little glucose is absorbed directly from the digestive tract of ruminants one of the targets for nutritional manipulation could be the glucogenic potential of the diet. This could be achieved by giving rumen-resistant starch or mono-propylene glycol. Both these adaptations increase glucose, insulin and insulin-like growth factor-1 plasma concentrations and stimulate ovarian follicle growth.

In multi-female multi-male group-living species, both sexes can copulate with diverse partners. According to the priority of access model, high-ranking males have higher access to females during their fertile phases than the lower-ranking competitors. However, when females' ovarian cycles are synchronized, dominant males are unable to monopolize all females, which gives a chance to lower ranking males to sporadically copulate and increase their likelihood to fertilize a female. Therefore, subordinate males perhaps show physiological characteristics allowing them to contend with the advantage that the dominant males already have. It was investigated if sperm counts, weight of the seminal coagulum, and testosterone levels showed any differences according to their social rank in male stump-tailed macaques. Testosterone levels increased linearly in relation to social rank (P = 0.004). No evidence was found that in the first ejaculation dominant rank was positively related to sperm counts and weight of the seminal coagulum. In the second ejaculation a positive correlation between dominant rank and sperm counts and weight of the seminal coagulum was found (P 0.001). By the third ejaculation there was a negative correlation between sperm counts and dominant rank (P 0.001), but no variability in the weight of the seminal coagulum. The results showed that high-rank is related to better physiological conditions to sustain multiple ejaculations, thanks to having higher testosterone levels.

Metformin has long been used in the treatment of polycystic ovarian syndrome (PCOS). Recently, sitagliptin has been reported to improve ovarian cycles and ovulation in PCOS. We suggest that a combination of sitagliptin and metformin can be more effective than either treatment alone in improving different aspects of PCOS.

This chapter reviews the normal anatomy, development, and histology of the rodent and human mammary gland. Mature resting, lactating, and atrophic mammary gland changes are discussed. Differences between rodent and human biologic structure and histologic findings are emphasized.

We evaluated the safety and postsurgical outcomes of endoscopic salpingectomy for sterilization of female Formosan macaques (Macaca cyclopis) as a method of population control. Nineteen adult female Formosan macaques were included in our study. The fallopian tubes of each anesthetized macaque were cauterized and excised endoscopically using a 2.7-mm rigid endoscope system. We recorded the complications encountered, and objectively scored the amount of hemorrhage throughout the procedure. Postoperative ovarian function was evaluated by monitoring the serum levels of sex hormones in ten of the macaques for two ovarian cycles following the salpingectomy. Two to 13 months later, eight of the 19 macaques underwent laparoscopy for the objective evaluation of inflammation at the surgical sites on the fallopian tubes. No major anesthetic- or surgical-associated complications were observed in any of the macaques. The hormonal evaluation showed cyclic ovarian function after salpingectomy in all of the ten macaques examined, and the parameters were comparable to those of other macaque species. The long-term postoperative level of inflammation at the surgical site was minimal to low, and was lower than that reported for other tubal occlusion techniques used in macaques. The use of a 2.7-mm rigid endoscope for salpingectomy in macaques is safe and efficient, with fewer postoperative complications than comparable sterilization techniques.

Objective Biomarkers associated with cancer screening (CA125, CA15‐3, CA72‐4, total prostate specific antigen [tPSA]) and the monitoring of pregnancy (pregnancy associated plasma protein‐A [PAPP‐A]) were measured during natural and stimulated ovarian cycles in disease‐free non-pregnant women to determine if they could reflect normal events relating to ovulation and/or endometrial changes. Methods A total of 73 blood samples (10 women) collected throughout the natural menstrual cycle, and 64 blood samples (11 women) taken during stimulated ovarian cycles, were analysed on the Roche Cobas e411 automated analyser. Results Detectable levels of tPSA were measured in at least one point in the cycle in 6/10 of women in the natural cycle and 10/11 of women in stimulated cycles, and CA72-4 was detected in only 12/21 women tested. Concentrations of CA125, tPSA, CA15‐3 and CA72‐4 showed no significant difference between the natural and stimulated ovarian cycle groups. On average the mean PAPP‐A of the natural group was (2.41±0.58) mIU/L higher than the stimulated group (t=4.10, P< 0.001). CA125 and CA15‐3 results were both significantly influenced by the stage of the cycle (P

Monitoring ovarian cycles through hormonal analysis is important in order to improve breeding management of captive elephants, and non-invasive collection techniques are particularly interesting for this purpose. However, there are some practical difficulties in collecting proper samples, and easier and more practical methods may be an advantage for some institutions and/or some animals. This study describes the development and validation of an enzymeimmunoassay (EIA) for progestins in salivary samples of African elephants, Loxodonta africana. Weekly urinary and salivary samples from five non-pregnant elephant cows aged 7–12 years were obtained for 28 weeks and analyzed using EIA. Both techniques correlated positively (r = 0.799; P

Objective To compare the results of two automated analysers by measuring reproductive hormones using the same quality control. Methods Results obtained by the Roche Cobas e411 automated analyser in a specialised fertility clinic were compared to the Siemens Centaur CP for the reproductive hormones oestradiol, progesterone, LH, FSH and hCG. Results Commercially-available quality control (QC) samples showed significant differences between the two assays for all five hormones at one or more levels. In clinical samples, the range of concentrations encountered was similar to the QC samples for LH and FSH but much higher for oestradiol, progesterone, and hCG showing the limitations of such QC samples in a specialised fertility setting when they are intended for general pathology use. There was a high degree of correlation for all hormones (all r >0.985) and a gradient close to 1 for all, except for hCG when the Siemens analyser read ≥1 000 IU/L ( r =1.209) and this is reflected in a large mean bias (-2 647.9 IU/L) and coefficient of repeatability (11 690.0 IU/L) when using a Bland-Altman plot. Conclusions Despite an overall agreement between the two assay platforms for progesterone, LH and FSH, small differences between the two analysers in the concentrations of oestradiol and hCG as encountered in natural ovarian cycles or at the time of pregnancy testing may require a redefinition of clinical cut-offs.

The objective of this study was to investigate the effects of abnormal ovarian cycles after superovulation treatment of Holstein Donor Cows. CIDRs were inserted into the vaginas of twenty two head of Holstein cows, regardless of estrous cycle. Superovulation was induced using folliclar stimulating hormone (FSH). For artificial insemination, donor cows were injected with PGF2α and estrus was checked about 48 hours after the injection. Then they were treated with 4 straws of semen 3 times, with 12-hour intervals. Embryos were collected by a non-surgical method 7 days after the first artificial insemination. The cows were considered to have resumed ovarian cyclicity on the day of ovulation if followed by regular ovarian cycles. Seventy two point seven percentage of the cows(16/22) had normal resumption of ovarian cyclicity(resumption within 40 days after superovulation), and 27.3%(6/22) had delayed resumption(resumption did not occur until＞40 days after superovulation). Delayed resumption Type Ⅱ(first ovulation did not occur until ≥40 days after superovulation, i.e. delayed first ovulation 13.6%) were the most common types of delayed resumptions. The mean numbers of total ova from < 10 and 10≤ of corpora lutea(CL) was 7.8±1.8 and 12.7±2.7, respectively. The number of transferable embryos differed between < 10 and 10≤ CL was 5.4±1.3 and 8.1±3.4, respectively. Four point five percentage of the cows(1/22) did not resumption their ovarian cyclicity until 60 days after superovulation treatment. Diverse researches on the superovulation treatment method that is suitable for high-producing Holstein donor cows would contribute to preventing ovarian cyclicity disorder, as well as to the early multiplication of cows with superior genes by increasing the utilization value of donor cows.

In captive callitrichid primates, female reproductive function tends to vary with social status. However, little is known about the interplay between these factors in wild groups. We report observations on normative ovarian function in dominant and subordinate female golden lion tamarins (Leontopithecus rosalia) living in wild groups. We monitored ovarian status by measuring, via enzyme immunoassay, concentrations of excreted pregnanediol glucuronide (PdG) and estrone conjugates (E1C) in fecal samples collected noninvasively from individuals in social groups in the Poço das Antas Biological Reserve, Rio de Janeiro State, Brazil. Dominant breeding females demonstrated steroid levels similar to those previously reported for wild cotton-top tamarin females, with statistically significant rises during pregnancy. The duration of elevation of fecal steroids in breeding females was ca. 4 mo, which corresponds with estimates of gestation from captive studies. Low steroid concentrations from December to June suggest a seasonally-related period of infertility in female golden lion tamarins. Dominant and subordinate females demonstrated several differences in endocrine function. In general, younger females living in intact natal family groups showed no evidence of ovarian cyclicity. We noted endocrine profiles consistent with ovulation and subsequent pregnancy for behaviorally subordinate females living in groups with unrelated males or in which a reversal in female dominance status occurred. Results suggest that in addition to changes in female reproductive endocrinology associated with puberty, the regulation of reproduction in females in wild callitrichid groups can be sensitive to status and relatedness to breeding males.

Lean and siscowet morphotypes of lake trout Salvelinus namaycush in Lake Superior are thought to be genetically separate, but the reproductive isolating mechanism is unknown. The testicular and ovarian cycles and reproductive hormone levels of these morphotypes were determined from May to October in populations east and west of the Keweenaw Peninsula in southern Lake Superior. The gonadosomatic index (GSI) increased from August to October for lean and siscowet males and females east of the Keweenaw Peninsula and for siscowets west of the Keweenaw Peninsula. Circulating estradiol-17β (E2) levels and ovarian GSIs increased simultaneously in females of both morphotypes. However, circulating 11-ketotestosterone (11-KT) levels in lean and siscowet males were not significantly elevated until October even though testicular GSIs increased by August. Transcripts of the follicle stimulating hormone (FSH) beta subunit (an indirect measure of FSH activity) increased in lean and siscowet males and females dur...

Sex differences have been reported in various phases of substance abuse, including relapse. In general, women show greater propensity to drug relapse than men, owing perhaps to divergent withdrawal experiences and increased reactivity to internal (emotional) and external (drug-associated) cues. Animal research tends to parallel human findings, revealing enhanced reinstatement of drug administration in females than males. Moreover, differences in vulnerability to relapse/reinstatement have been documented in women and female rodents across the ovarian cycles. Thus ovarian hormones seem to play an important role in determining susceptibility to relapse. Indeed, ovarian hormones interact with many of the neural circuits implicated in drug-primed, cue-instigated, and stress-induced relapse. By understanding the effects of ovarian hormones on the neural and behavioral mechanisms of drug relapse, sex differences and cyclical variations in relapse susceptibility can be elucidated and more effective treatment strategies can be explored.

The gonadotrophin-releasing hormone (GnRH) neurosecretory system involves both endocrine neurones and associated brain cells responsible for the control of GnRH release into the pituitary portal blood. Alternation between a pulsatile regime and the pre-ovulatory surge is the hallmark of GnRH secretion in ovarian cycles of female mammals. In previous studies, we have introduced a mathematical model of the pulse and surge GnRH generator and derived appropriate dynamics-based constraints on the model parameters, both to reproduce the right sequence of secretion events and to fulfil quantitative specifications on GnRH release. In the present study, we explain how these constraints amount to embedding time- and dose-dependent steroid control within the model. We further examine under which conditions the oestradiol-driven surge may be withdrawn by pre-surge progesterone administration and simulate both oestradiol and progesterone challenges in the pulsatile regime.

We studied two multimale-multifemale groups of black howler monkeys (Alouatta pigra) during a 14-month study (June 2006-July 2007) in Palenque National Park, Mexico to evaluate the ways in which their sexual behavior changes across ovarian cycles. We analyzed 231 fecal samples, collected every 2.2+/-1.4 days from five females. For four females, estradiol and progesterone profiles revealed an average (+/-SE) cycle length of 18.3+/-1.4 days. Copulations occurred significantly more frequently during the periovulatory period (POP), defined as the estimated day of ovulation +/-3 days (N=18). This was largely the result of cycling females soliciting sexual interactions during their POPs. Females directed their solicitations significantly more often toward "central" males of their group, who had close spatial associations with females at other times, compared with "noncentral" males, who did not associate closely with females. Central males rarely solicited sexual interactions, but instead monitored the females' reproductive status by sniffing their genitals, and maintained significantly closer proximity to females during their POPs, suggesting male mate guarding when conceptions are most likely to occur. Our findings indicate that the reproductive strategies of black howler central males and females coincide, highly skewing mating opportunities toward central males. Black howler females, however, occasionally choose to copulate with noncentral resident males or extra-group males during their POPs, undermining the ability of central males to monopolize all reproductive opportunities.

In the present study, pregnancy and the estrous cycle were monitored in captive brown brocket deer (Mazama gouazoubira) by measuring fecal progestagens with a commercial enzyme immunoassay (EIA), along with behavioral data. Fecal samples were collected twice a week during pregnancy and daily during the estrous cycle and post-partum period. It was possible to distinguish between inter-luteal and luteal phases of the estrous cycle. Behavioral estrus corresponded with low concentrations of fecal progestagens. Samples from two consecutive cycles were available from five hinds, and the mean estrous cycle (n = 10) was 26.9 ± 1.7 d (mean ± S.E.M.). However, when two extreme cycles (34 and 37 d) were deleted, the mean estrous cycle was 24.7 ± 1.2 d. Three animals became pregnant (gestation ranged from 208 to 215 d). After fertile breeding, progestagen concentration in these hinds remained among luteal phase concentrations throughout pregnancy, with the exception of a few peaks. Within 4 d post-partum, two hinds reached interluteal phase values, while one hind maintained luteal concentrations for at least 1 week.

The objective of this study was to evaluate postpartum resumption of ovulatory cycles among primiparous, suckled beef cows that were exposed continuously to mature bulls beginning at various intervals after calving. We sought to determine whether cumulative distributions of proportions of cows resuming ovarian cycles and interval from the start of bull exposure to resumption of ovarian cycling activity differed among cows exposed continuously (BE) or not exposed (NE) to bulls beginning on d 15, 35, or 55 after calving. Angus x Hereford cows (n = 56) were assigned randomly to one of six treatments in a 2 (exposure type) x 3 (day exposed postpartum) factorial arrangement. Blood samples were collected from each cow starting on d -1, and every third day until the end of experiment. An increase in baseline progesterone concentrations that exceeded 1.0 ng/mL in three consecutive samples was used as evidence of resumption of ovarian cycling activity. More (P < 0.05) BE cows resumed cycling activity by the end of the experiment than NE cows. Proportions of cows resuming cycling activity did not differ (P = 0.30) among cows exposed to bulls on d 15, 35, or 55 postpartum. Proportions of BE cows that were exposed to bulls on d 15, 35, or 55 were greater for each 10-d interval (P < 0.05) than those for NE cows during the first 40 d after exposure. More (P < 0.05) BE cows exposed to bulls on d 55 resumed cycling activity by 30 d after exposure than BE cows exposed to bulls on either d 15 or 35. Interval from calving to resumption of cycling activity was decreased (P < 0.05) by the presence of bulls. Day of exposure did not affect (P = 0.21) interval from calving to resumption of cycling activity; however, interval from day of bull exposure to resumption of cycling activity decreased (P < 0.05) linearly as day of exposure to bulls after calving increased. We conclude that exposing primiparous beef cows to bulls decreased the postpartum anovulatory interval and increased the proportion of cows that exhibit resumption of ovarian cycling activity, independent of day of bull exposure. Furthermore, cows exposed to bulls at progressively later intervals postpartum seemed to respond more rapidly to the biostimulatory effect of bulls than when they were exposed earlier in the postpartum anestrous period.

The influence of the ram effect, starting at lambing, on the resumption of ovarian activity (determined by repeated laparoscopy observations) and oestrous behaviour of autumn-lambing Barbarine ewes was evaluated in 64 multiparous Barbarine ewes in the permanent presence (R; n=32) or totally isolated (NR; n=32) from rams. In the R treatment group, all ewes (100%) ovulated at least once before the 100-day postpartum period, compared to only 50% (P

The Asian and African elephant populations in North America are not self-sustaining, and reproductive rates remain low. One problem identified from routine progestagen analyses is that some elephant females do not exhibit normal ovarian cycles. To better understand the extent of this problem, the Elephant TAG/SSP conducted a survey to determine the reproductive status of the captive population based on hormone and ultrasound evaluations. The survey response rates for facilities with Asian and African elephants were 81% and 71%, respectively, for the studbook populations, and nearly 100% for the SSP facilities. Of the elephants surveyed, 49% of Asian and 62% of African elephant females were being monitored for ovarian cyclicity via serum or urinary progestagen analyses on a weekly basis. Of these, 14% of Asian and 29% of African elephants either were not cycling at all or exhibited irregular cycles. For both species, ovarian inactivity was more prevalent in the older age categories (>30 years); however, acyclicity was found in all age groups of African elephants. Fewer elephant females (∼30%) had been examined by transrectal ultrasound to assess reproductive-tract integrity, and corresponding hormonal data were available for about three-quarters of these females. Within this subset, most (∼75%) cycling females had normal reproductive-tract morphologies, whereas at least 70% of noncycling females exhibited some type of ovarian or uterine pathology. In summary, the survey results suggest that ovarian inactivity is a significant reproductive problem for elephants held in zoos, especially African elephants. To increase the fecundity of captive elephants, females should be bred at a young age, before reproductive pathologies occur. However, a significant number of older Asian elephants are still not being reproductively monitored. More significantly, many prime reproductive-age (10–30 years) African females are not being monitored. This lack of information makes it difficult to determine what factors affect the reproductive health of elephants, and to develop mitigating treatments to reinitiate reproductive cyclicity. Zoo Biol 23:309–321, 2004. © 2004 Wiley-Liss, Inc.

Objective: Endometrial perfusions were measured by Doppler ultrasound to evaluate the influence of spontaneous menstrual cycles and to study the effect of clomiphene citrate. Methods: Flow waveforms in right and left uterine arteries were obtained by using trans‑ vaginal color Doppler ultrasonography in infertile women with 60 spontaneous menstrual cycles and 37 clomiphene citrate stimulated cycles from the follicular to the luteal phase. Results: In the spontaneous menstrual cycles the uterine arterial blood flow increased significantly from the follicular phase to the day of ovulation and then increased markedly to about 200~230% of the follicular phase after the 6 th day of ovulation. In the clomiphene citrate stimulated cycles the uterine arterial blood flow did not change during the periovulatory period and then increased significantly to about 180~220% of the follicular phase after the 6 th day of ovulation. Conclusions: In the present study the clomiphene citrate stimulated cycles showed lower endometrial perfusion during the periovulatory period compared with those in the spontaneous menstrual cycles. The results suggest that the assessment of endometrial perfusion with Doppler ultrasound can be used to reveal unexplained infertility problems in induced ovarian cycles. (J Nippon Med Sch 2002; 69: 328―332)

Aspects of the influence of nutrition on the degree of ovarian development in selected anautogenous Diptera are reviewed. The Diptera considered are several mosquito species, with emphasis on Aedes aegypti, the house fly, Musca domestica, the Australian bush fly, M. vetustissima and the blowflies, Lucilia cuprina and Phormia regina. All the selected species display discrete ovarian cycles in which all oocytes destined to reach maturity in a particular ovarian cycle develop synchronously. In these species, the proportion of females maturing oocytes and, where such data exist, the number of oocytes they mature are positively correlated with the amount of any particular nitrogen-containing material ingested or given by enema or by infusion. In addition, the degree of ovarian development may be affected by the chemical composition of nitrogen-containing food. Possible physiological bases for the observed relationships are discussed. Available evidence suggests that whether or not a female matures any oocytes is hormonally regulated and that the number of oocytes matured is probably regulated by the availability of nutrients. Some approaches that might further elucidate the physiological regulatory mechanisms involved in ovarian development are outlined.

Living organisms have developed a multitude of timing mechanisms--"biological clocks." Their mechanisms are based on either oscillations (oscillatory clocks) or unidirectional processes (hourglass clocks). Oscillatory clocks comprise circatidal, circalunidian, circadian, circalunar, and circannual oscillations--which keep time with environmental periodicities--as well as ultradian oscillations, ovarian cycles, and oscillations in development and in the brain, which keep time with biological timescales. These clocks mainly determine time points at specific phases of their oscillations. Hourglass clocks are predominantly found in development and aging and also in the brain. They determine time intervals (duration). More complex timing systems combine oscillatory and hourglass mechanisms, such as the case for cell cycle, sleep initiation, or brain clocks, whereas others combine external and internal periodicities (photoperiodism, seasonal reproduction). A definition of a biological clock may be derived from its control of functions external to its own processes and its use in determining temporal order (sequences of events) or durations. Biological and chemical oscillators are characterized by positive and negative feedback (or feedforward) mechanisms. During evolution, living organisms made use of the many existing oscillations for signal transmission, movement, and pump mechanisms, as well as for clocks. Some clocks, such as the circadian clock, that time with environmental periodicities are usually compensated (stabilized) against temperature, whereas other clocks, such as the cell cycle, that keep time with an organismic timescale are not compensated. This difference may be related to the predominance of negative feedback in the first class of clocks and a predominance of positive feedback (autocatalytic amplification) in the second class. The present knowledge of a compensated clock (the circadian oscillator) and an uncompensated clock (the cell cycle), as well as relevant models, are briefly re viewed. Hourglass clocks are based on linear or exponential unidirectional processes that trigger events mainly in the course of development and aging. An important hourglass mechanism within the aging process is the limitation of cell division capacity by the length of telomeres. The mechanism of this clock is briefly reviewed. In all clock mechanisms, thresholds at which "dependent variables" are triggered play an important role.

Long-term experiments were conducted to study the progression of vitellogenic cycles in Rana tigrina (an annual breeder) having different foraging backgrounds and held under conditions of weekly or daily food supply and in presence or absence of abdominal fat bodies. They were autopsied in June to assess fecundity. In nature an adult R. tigrina produces on an average 4,000 eggs/100 g body mass (b.m.) And spawns in June-July following monsoon rains. Weekly feeding from July to next breeding season, June resulted in a significant decrease in both fecundity (1700 eggs/100 g body b.m.) And mean size of eggs, compared to well-fed or wild-caught frogs. The abdominal fat bodies were barely seen in frogs fed weekly throughout, whereas in frogs fed weekly from July-December but daily from January onwards, the fat bodies became noticeable (1% of b.m.) And number and mean size of eggs increased significantly over those fed weekly throughout. Frogs captured in January possessed enlarged fat bodies (5% of b.m.), depicting a good foraging history. Maintenance of these frogs on a weekly feeding regimen led to an exhaustion of fat stores. They produced less number of eggs (2, 000/100 g b.m.) As compared to wild frogs but of normal size, whereas daily feeding slowed down a depletion of fat body mass and also significantly increased fecundity (3,000/100 g b.m.) Over the weekly fed individuals. Sham operation or fat body ablation in October or February had no significant effect on total fecundity per se (3,000-3,500 eggs/100 g b.m.) Compared to that of wild-caught frogs. However, eggs were significantly smaller due to fat body ablation despite daily feeding. The study shows that food abundance/fat bodies influence egg size and number in R. tigrina and that a direct or indirect functional relationship exists between fat body and ovarian cycles that are characteristically inverse to each other. J. Exp. Zool. 286:487-493, 2000.

Faecal oestrogen and progestin analyses were used to assess ovarian activity in non-pregnant scimitar-horned oryx (Oryx dammah) during a 13-month interval. Mean (± SE) luteal phase, interluteal phase and oestrous cycle duration were 18.8 (± 0.5), 5.1 (± 0.2) and 23.8 (± 1.3) days, respectively. All females exhibited a synchronized anovulatory period that ranged from 36‐95 days during spring. Short ovarian cycles (10.6 (± 0.8) days) were observed intermittently throughout the year and before the spontaneous resumption of oestrous cyclicity. Periovulatory peaks in oestrogen concentrations were detected for 42.5% (31/73) of ovarian cycles. A parallel analysis of reproductive data from the North American studbook (1985‐1994) revealed that captive-held scimitar-horned oryx gave birth throughout the year. Sex ratio at birth was male-biased (54.4%), and 19.1% of all calves failed to survive to 6 months of age (220 out of 1149 births). Only 0.7% of births resulted in twins. Median interbirth interval was 277 days, and 75% of these intervals were less than 332 days. Interbirth interval was extended (P < 0.05) if parturition occurred from January through May. In summary, the scimitar-horned oryx is a seasonally polyoestrous species that experiences a distinct anovulatory period during spring in north-east America.

The effect of lambing date on the subsequent onset and duration of ovarian cyclicity in Mule (Bluefaced Leicester × Scottish Blackface) ewes was investigated. Nineteen ewes which had lambed in January (16 January 1993 (s.e. 3 days)) and been weaned in February-March and 22 comparable ewes which had lambed in May (14 May 1993 (s.e. 2 days)) and been weaned on 23 August were maintained at pasture as two isolated groups. A raddled vasectomized ram was continually present with each group from 14 July 1993 to 26 May 1994 and marked (oestrous) ewes were recorded twice weekly. Ovarian activity was assessed by measuring peripheral progesterone concentrations in blood samples collected twice weekly and by laparoscopic viewing of the ovaries of all ewes during October, January and March. The onset and duration of ovarian activity were significantly affected by the previous lambing date. For January and May lambing ewes, mean dates of onset were 5 September 1993 (s.e. 2 days) v. 25 September 1993 (s.e. 4 days) (P < 0·001) and of cessation were 5 April 1994 (s.e. 5 days) v. 10 April 1994 (s.e. 3 days). Mean durations of ovarian activity were 212 (s.e. 6) and 195 (s.e. 5) days (P < 0·05) during which 12·4 (s.e. 0·29) and 11·5 (s.e. 0·38) ovarian cycles respectively were recorded. Ovulation rate was not affected by previous lambing date but was significantly lower in March compared with October (January lambing ewes 1·7 (s.e. 0·1) v. 2·3 (s.e. 0·1) (P < 0·001); May lambing ewes 1·6 (s.e. 0·1) v. 2·1 (s.e. 0·1) (P < 0·01)). Results demonstrate that (i) Mule ewes have a potential breeding season of up to 8 months duration; (ii) the onset and duration of ovarian activity can be influenced by previous lambing date; and (Hi) a seasonal decline in ovulation rate may, in practical terms, result in a lower lambing percentage for animals bred towards the end of their natural breeding period.

Reproductive patterns of wild cotton-top tamarin (Saguinus oedipus) females located in La Reserva Forestal Protectora Serrania de Coraza-Montes de Maria in Coloso, Colombia, were examined using long-term behavioral observations and fecal steroid analysis. Using an enzyme immunoassay, we analyzed fecal samples for E1C and PdG. Comparisons of reproductive cycles of a reproductively active female and her daughters were made. An inhibition of ovarian cycles has been observed in daughters living in their families. However, daughters also exhibited normal ovarian cycling that subsequently resulted in pregnancy. Factors influencing the fertility are discussed as they relate to the reproductive strategies of wild cotton-top tamarin females. Am. J. Primatol. 43:329–337, 1997. © 1997 Wiley-Liss, Inc.

The continuous, subcutaneous infusion of native GnRH into seasonally anovulatory mares stimulates the synthesis and secretion of LH without pituitary refractoriness, offering opportunities to markedly accelerate the timing of ovulation within the operational breeding season. Herein, we tested the hypothesis that ovarian cycles induced in winter anovulatory mares using continuous administration of native GnRH for 28 days, beginning in either early February or early March (North America) would not revert to an anovulatory state after treatment withdrawal. Anovulatory mares received sham pumps (control) or native GnRH (100 μg/h) for 28 days beginning from February 2 or 3 (GnRH-Feb) or March 2 or 3 (GnRH-Mar). Mean concentrations of LH were five- to seven-fold greater during February in the GnRH-Feb group compared with control and GnRH-Mar groups through February and ending on March 2 or 3. However, concentrations of LH returned to the winter baseline within 3 to 11 days after pump removal and all GnRH-Feb mares failed to remain cyclic after treatment withdrawal. Correspondingly, during March, concentrations of LH in the GnRH-Mar group were greater (P0.001) than in the control and GnRH-Feb groups during the 28-day treatment period. Follicular growth and frequency of ovulation (6/10 GnRH-Feb; 9/10 GnRH-Mar, 1/11 controls, respectively) were greater (P0.01) in GnRH-treated mares. Ovulatory cycles continued in five of nine GnRH-Mar mares that ovulated, with interovulatory intervals of 15 to 24 days; whereas, three of nine mares had extended (33-42 days) interovulatory intervals and one of nine mares had a persistent CL after cessation of treatment. In summary, continuous administration of native GnRH for 28 days, beginning in early February or March, elevated circulating LH adequately to stimulate follicular growth and ovulation up to 60 days earlier than in untreated controls. However, if continuous, subcutaneous infusion of GnRH is selected as the only pharmacologic or managerial intervention, and mares are not pregnant, treatment must be continued at least until the end of March. This will improve the likelihood of a normal interovulatory interval after treatment withdrawal.

Differences in spawning seasonality, inferred from ovarian cycles, and microhabitat use for two closely related Fundulus species were not effective as potential reproductive isolating mechanisms. Seasonal spawning periodicity of F. olivaceus and F. euryzonus as shown by changes in mean egg diameter and mean number of mature eggs recovered from ovaries showed nearly identical temporal patterns in reproductive activity. Peak egg development was between April and May and was lowest by the end of August. Univariate comparisons of 11 environmental variables associated with aggregations of Fundulus spp. revealed highly significant differences in several of these variables. However, individuals of both species were frequently collected together, and microhabitat differences did not remove the potential for mismating.

A nonsurgical technique for the recovery of uterine stage preimplantation embryos was developed for the common marmoset (Callithrix jacchus). In 54 flush attempts, using 19 different animals, 54 morphologically normal embryos, seven unfertilized oocytes or degenerate embryos, and five empty zonae pellucidae were recovered, giving a recovery rate of 1.0 embryo per flush or 1.2 ovulation products per flush. Because the ovarian cycles of common marmosets can be synchronized with prostaglandin PGF2 alpha, multiple marmosets can be flushed in a short period, providing age-matched embryos for controlled experiments.

A total of 40 mature Icelandic ewes were studied during four breeding seasons. Blood samples were collected at regular intervals and the progesterone concentrations assayed. The progesterone profiles were evaluated and the time of onset, cessation and duration of the breeding season as well as the pattern of the luteal function in non-pregnant and pregnant ewes was established. On average, the onset of the breeding season occurred on 15 November and its cessation on 20 February. The length of the breeding season was 97 ± 24 days. The earliest onset was in October and ovarian cyclicity ceased in April in the ewes with the longest breeding period. The onset of cyclicity spanned 53 days and its cessation 90 days. In 90% of the ewes the onset spanned 28 days and the cessation 70 days. In relation to daylength, all the ewes were cycling during the period when the centre of the sun was 5° above the horizon at noon with decreasing daylength until it was 5° above the horizon with increasing daylength (sunrise-sunset 5.5 h). The length of the ovarian cycle was 16 ± 2 days. The length of the luteal phase was 11 ± 2 days and was not significantly different between cycles but the mean progesterone concentration of the luteal phase of the first ovarian cycle was lower and the area under the progesterone curve was smaller (P

LH is a glycoprotein that plays a crucial role in folliculogenesis during the natural ovarian cycles. It has the same activity and shares receptors with hCG. However the use of LH in combination with FSH in controlled ovarian stimulation remains controversial. A practical approach concerning the usefulness of LH according to the endogenous level of LH is described herein. Specific groups of patients can benefit from ovarian stimulation with LH. New applications of LH/hCG activity are also discussed.

The South American shrimp Palaemonetes argentinus inhabits inland freshwater habitats such as lakes, rivers and streams, but also coastal brackish marshes and lagoons. Hence, this so-called "freshwater" shrimp is expected to be able to reproduce in a wide range of salinities. Here we examined effects of three salinities (1, 15, 25 ppt) on survival and reproductive cycle of females originating from two separate populations in Argentina: 1) Lake Chascoms (LC), a shallow inland lake with low and stable ionic concentrations; and 2) Vivorat Creek (VC), a lotic stream draining into the adjacent brackish lagoon Mar Chiquita, where salinity is tide-dependent. After an observation period of four months, survival was generally high, without showing significant differences between salinities or populations. Ovarian maturation was measured on a scale ranging from "empty" ovaries ( females with newly laid eggs) to fully developed ovaries ( females ready to spawn). Most LC shrimps (> 80) developed their ovaries again after an initial egg extrusion (beginning of the experiment) and produced new eggs at all tested salinities. In VC shrimps, ovarian maturation and egg deposition were successful in both the lowest and the highest salinity (1, 25 ppt), but developed ovaries were resorbed in most individuals at the intermediate salinity (15 ppt). Ovarian resorption was never observed at the highest salinity treatment, thus this phenomenon may have been provoked by unknown factors other than ionic concentration. At 15 and 25 ppt, the beginning of vitellogenesis started later and the total time to ovary maturation was longer than at 1 ppt, lengthening in both populations the time between consecutive spawning of eggs by nearly 10 days. Irrespective of the origin of a population, female P. argentinus survived and completed all reproductive events under a wide range of salinities, which supports the hypothesis that this species is in an early stage of evolutionary invasion of freshwater habitats. © 2010 The Crustacean Society. Fil: Ituarte, Romina Belen. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina Fil: Spivak, Eduardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentina Fil: Camiolo, Martina Daniela. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina Fil: Anger, Klaus. Institut fur Polar und Meeresforschung; Alemania

The ovarian cycles of female rats become synchronized when they live together, as do the cycles of many other mammals. Ovarian cycles also become synchronized when rats live apart if they share a common air supply, indicating that ovarian-cycle synchrony is mediated by pheromones. We developed a coupled-oscillator model of ovarian-cycle synchrony to test several hypotheses about its pheromonal and neuroendocrine mechanisms and to guide our experimental research. The model spans three levels of organization: the group, the rat, and the neuroendocrine components of the ovarian system. The ovarian system (not the ovaries themselves) are modeled as an oscillating system. Coupling among ovarian systems is mediated by the exchange of two pheromones, one that delays the phase of the ovarian system and one that advances it. Computer simulation experiments showed that this coupled-oscillator model can explain the levels of ovarian-cycle synchrony observed in groups of female rats while, at the same time, matching an empirical distribution of ovarian-cycle lengths. By successfully matching computer simulation data with empirical data, we were able to infer theoretical predictions in a number of areas: (1) effect of initial conditions on the probability that a group will change to different synchrony level and phase relationships, i.e. the transition probability between all synchrony levels and phase relationships; (2) effects of individual differences in pheromone sensitivity on ovarian-cycle synchrony; (3) the timing of pheromone sensitivity during the ovarian cycle; and (4) the existence of partial luteinizing hormone surges, which may cause the "spontaneous" prolonged ovarian cycles associated with ovarian-cycle synchrony. The paper concludes by discussing the integrative role of this model for experimental research. In particular, we focus on the role of this model in interpreting theoretical aspects of ovarian-cycle synchrony as well as for guiding future experimental research into its mechanisms and functions.