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PubMed1975

Motility of the oviduct and uterus of the cow during the oestrous cycle.

Recordings of electrical activity of the oviduct and uterus were obtained during three oestrous cycles in cows fitted with an extra-cellular multi-electrode assembly. The stages of the cycle were identified by the appearance of the cervico-vaginal secretions and changes in the peripheral plasma level of progesterone were determined by radioimmunoassay. A gradual transition from local non-propagating electrical activity to propagating electrical activity with increase in the duration of contractions and then of their amplitude occurred 48 hr before the onset of oestrus. The transition coincided with a rapid decrease in progesterone level from 5 to 10 ng/ml to less than 0-1 to 0-4 ng/ml. This phenomenon was recorded from all uterine electrode sites, but was most marked at the uterotubal junction. Two days before oestrus, trains of potentials and bursts of activity became progressively grouped, apparently randomly, into prolonged phases in the distal portion of the oviduct and over the entire myometrium. During oestrus, the phases of activity became synchronized at these sites and both their amplitude and frequency reached a maximum. The strength but not the frequency of the phases diminished progressively 3 days after oestrus, followed by relative inactivity. The last remaining zone of activity was the uterotubal junction. During oestrus, the activities of the oviduct and the uterus were modified by oxytocin and adrenaline, the effect of the former being more marked on the uterus and that of the latter on the oviduct.

Animals↗

PubMed1975

Synchronization of oestrus in mares with a prostaglandin analogue and HCG.

Following an initial observation period of 13 days when plasma progesterone levels were determined, synchronization of oestrus and ovulation was investigated in thirty-three mares treated with a prostaglandin analogue ('Equimate') and HCG. Two courses of treatment were given 8 days apart and each consisted of a single intramuscular injection of Equimate (250 mug) followed 6 days later by an intramuscular injection of HCG (2500 i.u.). The first course was designed to remove all luteal tissue and to induce ovulation of any follicles that developed in response to the withdrawal of progesterone. The second course had the effect of synchronizing oestrus and ovulation following luteolysis of the induced CL in all the mares. A high proportion of treated mares responded by ovulation within 24 and 72 hr after the second HCG injection and provided fertility was not disturbed, the prognosis for a high success rate by the double treatment was good. The plasma progesterone level is a reliable criterion of ovulation and would replace the need for the clinical procedures normally employed to determine the onset of oestrus and follicle rupture.

Animals↗

PubMedDate not supplied

Chronosynergistic effects of lighting schedule-shift and cefodizime on plasmacytoma growth and host survival time.

Lighting regimen shifts can modify the effects of cefodizime, for the purpose of a chronoimmunomodulation. Two experiments were carried out on male and female LOU rats inoculated subcutaneously with plasmacytoma cells. Some rats were kept on their original LD12:12 regimen, whereas others, after tumor implantation, were subjected every second day to 6-h shifts, instituted, in alternation, as advance or delay. Daily treatment with cefodizime or placebo started when, overall, about 50% of the animals had developed a palpable tumor. A subgroup of animals contributed daily smears for the determination of the estrus cycle and further provided core temperature and activity data by telemetry. In Experiment I, the repeated shifting of the LD regimen was associated with survival time prolongation (p less than 0.05), irrespective of drug administration. Moreover, in those (female) rats repeatedly exposed to shifts of the lighting schedule, cefodizime was found to prolong survival time (p less than 0.05). The effects of cefodizime vs placebo on survival time were found to be circadian stage-dependent. In Experiment II, differing from Experiment I in the initial conditions before the institution of the shifts, cefodizime treatment was associated with a prolongation of survival time of the female rats kept on a fixed LD12:12 regimen. Both male and female rats again showed a circadian stage-dependence of the cefodizime effect. These results suggest that interactions between synchronizers of rhythms (such as shifts of the lighting regimen, the latter simulating the daily routine) and immunomodulating agents such as cefodizime may be optimized to improve treatment strategies against cancer and other diseases.

Animals↗

PubMed1994

Splitting of porcine embryos at the four-cell or morula stage.

Porcine embryos obtained from estrus-induced prepuberal gilts were split at the 4-cell and morula stage. The in vitro development of the demi-embryos was compared with that of intact control embryos. The intact control embryos developed according to expectation. The in vitro survival of the demi-embryos was inferior to that of the respective controls. The splitting of 4-cell embryos was easier to accomplish and more efficient than the splitting of morulae. The in vitro development of the 4-cell embryos was also slightly better, although this difference was not significant. In vitro development of demi-embryos originating from morulae split at room temperature was slightly although nonsignificantly inferior to that of demi-embryos from morulae split on a warming stage at 37 degrees C. Between 14 and 18 demi-embryos were transferred to synchronous recipient gilts after 24 to 48 h of culture. Of 3 gilts receiving split 4-cell embryos, 1 gilt aborted 2 normal fetuses on Day 90 of pregnancy and 1 carried a single piglet to term. Of the 4 gilts receiving split morulae, 1 gilt had 4 normal and 3 degenerated fetuses upon slaughter on Day 35 of pregnancy.

Journal Article↗

PubMed1978

[Quantitative histoenzymologic characteristics of the submaxillary salivary glands of white rats during an ovarian cycle].

Ovarian cycle in albino rats was applied to ascertain the problem of the relationship between the salivary and endocrine glands, and also of the extent of participation of individual components of the salivary glands with different functional orientation in the endocrine regulation of individual components of the salivary glands. The content of protein, mucopolysaccharides, DNA, and RNA, the activity of NAD- and NADP-diaphorase, alkaline phosphatase, malate and isocitrate dehydrogenase, alpha-leucine-aminopeptidase was studied. Cytospectrophotometric analysis showed that synchronous changes in the activity of the enzymes under study occurred in all the portions of the salivary glands, depending on the ovarian cycle phases. Of the four successive phases of the cycle the greatest activity of the enzymes and of the protein and mucopolysaccharide content was noted during the proestrus and metaestrus. Different metabolic processes were observed in the salivary ducts in comparison with other parts of the gland; this was apparently connected with peculiarities of the secretion and hormone production.

Alkaline Phosphatase↗

PubMed1980

Effects of HCG with oestradiol benzoate on the luteal function in gilts.

Human chorionic gonadotrophin (HCG) combined with oestradiol benzoate was tested for induction and synchronization of heat in gilts. Judging from the progesterone levels in the blood, several of the gilts were already exhibiting spontaneous oestrous cyclicity on the day of treatment. Only gilts with low blood progesterone levels on the day of treatment showed standing oestrus within the expected time. On the basis of the results a second trial was carried out to elucidate the influence of the hormone compound on the ovarian activity in gilts during the luteal phase.

Animals↗

PubMed1996

Ovulatory cycles and anovulatory periods in the addax (Addax nasomaculatus).

Changes in serum oestradiol and progesterone were measured to study their dynamics during ovulatory cycles in six female addax, an endangered antelope. Blood was collected three times per week, during chute restraint, for 3 months (November to February) before introduction of a male, and continued until pregnancy was diagnosed with ultrasound. Serum was analysed by enzymeimmunoassay. Mean luteal phase, interluteal phase, and cycle durations were 22.7 +/- 2.0, 8.78 +/- 0.5 and 32.3 +/- 1.7 days, respectively. Ultrasonography revealed coiled uterine horns and maximum follicle and corpus luteum diameters of 15 and 27 mm, respectively. Each female experienced an anovulatory period, during which oestradiol continued to fluctuate, but progesterone remained below 2 ng ml-1. These periods ranged from 39 to 131 days and were not synchronous; ovulatory cycles resumed spontaneously in all females. All four females placed with a male conceived. Because addax give birth all year round, they are not considered seasonal breeders. The sporadic periods of anovulation that occurred during the winter months of this study suggest a possible seasonal effect. However, systematic sampling has not been conducted during summer and early autumn and will be necessary to address this question.

Anestrus↗

PubMed1982

Spontaneous motility of the cervix in cyclic and ovariectomized ewes and changes induced by exogenous hormones.

Continuous recordings of the electrical and mechanical activities of the cervix were made. Two basic patterns of electrical signal, short spike bursts and long spike bursts, showed close mechanical relationships with the record of mechanical activity. Electrical activity was organized in myoelectrical complexes including the regular alternation of phases of irregular spiking activity and phases of regular spiking activity. The myoelectrical complexes of the cervix existed independently of the sexual status although the frequency of recurrence did vary. The highest frequency was recorded during the periovulatory period around oestrus when each complex was synchronized with a similar pattern recorded from the uterine horns. At the end of the periovulatory period, the irregular spiking activity decreased, the myoelectrical complex pattern of the cervix and uterine horns consisting mainly of regular spiking activity at a high frequency until metoestrus. During the luteal phase, only the cervix remained active, with myoelectrical complexes formed mainly by phases of regular spiking activity recurring at long intervals. This pattern was also recorded after ovariectomy in the absence of hormonal treatment.

Action Potentials↗

PubMed1999

Role of male-female interaction in regulating reproduction in sheep and goats.

The induction of synchronous ovulatory activity in anovulatory sheep and goats after the introduction of males, the 'male effect', has probably been used to advantage since these species were domesticated and the underlying physiological and behavioural mechanisms have been progressively elucidated over the past 50 years. Less well understood is the analogous effect of oestrous females on males. This review examines the nature and importance of these male-female interactions in sheep and goats, and describes the most important internal and external factors influencing the reproductive outcomes of such interactions. It is proposed that the male and female effects are both components of a self-reinforcing cycle of stimulation that, under ideal conditions, culminates in the synchronous very rapid onset (within days) of fertile reproductive activity. However, precisely because of the speed of this response, it is suggested that mechanisms have evolved to limit its efficacy, and thus prevent conception at inappropriate times. The complexity of these factors and the interactions between them are highlighted, and a broad conceptual framework for understanding them is proposed based upon an appreciation of variation in both the responsiveness of the target animal and the quality of the signal from the signalling animal.

Animal Nutritional Physiological Phenomena↗

PubMed1997

[Sex steroid profiles and ovarian activities of the female panda Yan Yan in the Berlin Zoo].

The nine years old giant panda YAN YAN was received in April 1995 on loan for 5 years to the Berlin Zoo. Urine samples were collected daily or every second day from April 1995 to June 1996 in order to follow up sex hormone secretions and ovarian activities. Conjugated steroids were hydrolysed, extracted and measured with two enzyme immuno assays (EIA) being specific for either total oestrogenes or pregnandiol. The evaluation of the hormone secretion pattern yielded the following results: There is a significant synchronous cross correlation between estrogen and progestin metabolites secretion indicating its simultaneous synthesis. In addition, we found a regular increase and decrease of both hormones with a 13 days interval. This secretory pattern indicates repeating development and atresia of follicle cohorts with a cycle length of about 13 days. Only a single period of slightly elevated oestrogen synthesis was monitored in Feb. 96 without any signs of oestrus. Obviously the stimulation of ovarian function was insufficient for complete ovulation and corpus luteum formation.

Animals↗

PubMed1999

Effect of stage of anestrus on the induction of estrus by the dopamine agonist cabergoline in dogs.

Beagle bitches were administered the dopamine D2 receptor agonist cabergoline in 3 groups of 5 animals each, starting on known days of the estrous cycle. Cabergoline treatment was started in either early anestrus (Days 93 to 108), mid-anestrus (Days 123 to 156), or late anestrus (Days 161 to 192) at doses of 5 ug/kg/d, per os, and was continued until the confirmation of induced proestrus or for 40 d. Reproductive parameters were compared with those in 5 control anestrous bitches (Days 90 to 150). In control bitches, the mean (+/- SEM) interval to the next proestrus (73+/-11 d) resulted in an interestrus interval (192+/-9 d) similar to that of the previous cycles (196+/-11 d). In 14 of the 15 cabergoline-treated bitches, the next proestrus occurred within 4 to 30 d, was premature in early and mid-anestrous bitches and developed with low variability within groups. The resulting intervals to proestrus in bitches treated with cabergoline in early anestrus (20+/-2 d), mid-anestrus (14+/-3 d) and late anestrus (6+/-1 d) resulted in interestrus intervals in those groups of 131+/-5, 166+/-7 and 196+/-2 d, respectively. In response to treatment, interestrus intervals were reduced (P<0.05) and more synchronous (P<0.05) in early and mid-anestrus bitches, and were more synchronous (P<0.05) in late-anestrous bitches compared with those of control bitches or those of the previous cycle. Periovulatory estradiol and progesterone profiles of induced cycles in treated bitches were similar to those of spontaneous cycles in control bitches. Four of 5 control bitches and 12 of the 14 responding cabergoline-treated bitches became pregnant and produced normal litters. Plasma prolactin concentrations at Days 2 and 5 of treatment (0.3+/-0.1 ng/mL) and at the onset of proestrus shortly before the end of treatment (0.4+/-0.1 ng/mL) were lower (P<0.05) than those present in anestrus prior to treatment (1.7+/-0.6 ng/mL) or in control bitches. Prolactin was also low at the onset of proestrus in control bitches (0.5+/-0.2 ng/mL). The results demonstrate that prolactin-lowering doses of the dopamine agonist cabergoline can terminate the normal obligate anestrus in dogs, and that the effect occurs more slowly in early anestrus than in mid or late anestrus.

Anestrus↗

PubMed2003

[Immune response to equine Chorionic Gonadotropin used for the induction of ovulation in goats and ewes].

In dairy goats and ewes the use of equine Chorionic Gonadotropin (eCG) as a convenient hormone for the induction of ovulation is necessary for out-of-season breeding and artificial insemination (AI). Treatment for induction and synchronization of ovulation consists of a progestagen delivered by vaginal sponge, followed by an eCG injection. In some females, the first injection of eCG induces a humoral response with high concentrations of anti-eCG antibodies in contrast to other females displaying a very low concentration of anti-eCG antibodies. Females eliciting a low response were also poor responders after the following treatments. Conversely, high responders at the first treatment systematically yielded high immune responses upon the following treatment. By a molecular genetic approach using microsatellites we showed that the anti-eCG immune response phenotypes were associated with MHC class II polymorphism. Females with high residual antibody concentrations at the time of eCG injection exhibited a much lower kidding rate than other females did. Lower fertility of these females, inseminated at a fixed time after eCG treatment (43H for goats and 55H for ewes), might be due to the delay in estrus occurrence and the pre ovulatory LH surge. Consequently, under field conditions old females selected for AI are only those with low residual anti-eCG antibody concentrations and old females with high residual antibody concentration are culled from AI breeding because of their low fertility during the previous year. So we have undertaken comparative studies to establish if the anti-eCG immune response is correlated with the global immunity in animals.

Animals↗

PubMed1980

Collection, description and transfer of embryos from cattle 10--16 days after oestrus.

Of 226 donor cattle treated with PMSG to induce superovulation, 76.5% responded with 3 or more ovulations. Flushing at surgery or slaughter 10-16 days after oestrus recovered eggs and embryos that represented 49.3% of the number of ovulations. Of those recovered, 73.3% were embryos, an average yield of 4.0 embryos/treated cow or 4.8 embryo/flushed cow. The location of eggs and embryos was determined in 65 of the donors. Embryos and unfertilized eggs (6.1% of those recovered) were occasionally found in the oviducts. Empty zonae pellucidae were also found in the uterus on all days. The lengths, or diameters, of embryos were extremely variable within days and within donors, but mean values indicated logarithmic growth between Days 10 and 16. Eighty-four synchronous (+/- 1 day) recipients received single embryos, and 51 recipients twin embryos, by surgical transfer. Pregnancies were obtained in recipients up to Day 16 but not on Day 17, indicating the stage by which an embryo must be present to prevent luteolysis. The overall pregnancy rate at Day 42 was 50.4% and further 18.1% of the recipients exhibited extended oestrous cycles. Of 35 recipients that were allowed to go to term, 12 lost their pregnancies, most often between Days 42 and 63.

Abortion, Veterinary↗

PubMed2001

Influence of oestrus synchronization on male reproductive success in the domestic cat (Felis catus L.).

Previous studies have predicted that the availability over time of females in oestrus influences the variance of male reproductive success in a given year. When females are spatially aggregated, they represent a potentially defendable resource for each male when oestrus is asynchronous, and the most competitive males are expected to gain priority of access to receptive females. When females breed synchronously, a single male, even when highly competitive, is not able to prevent them from mating with other males. This hypothesis was tested in a large multimale-multifemale group of domestic cats, Felis catus, which was monitored for three years. The results support the prediction that the variance in male reproductive success was four times greater in years when females bred asynchronously, and dominant males sired the highest proportion of offspring. We conclude that the temporal availability of mates plays a role in the adoption of reproductive tactics in the domestic cat.

Animals↗

PubMed1990

Human menopausal gonadotropin induces ovulation in sheep, but embryo recovery after prostaglandin F2alpha synchronization is compromised by premature luteal regression.

Using pregnant mares' serum gonadotropin (PMSG) and follicle stimulating hormone (FSH-P) as conventional gonadotropins, human menopausal gonadotropin (hMG) was tested for its comparative ability to induce multiple ovulations in sheep. Estrous cycles were synchronized using either prostaglandin F2alpha (PGF2alpha) or progestogen (MAP)-impregnated pessaries. During the mid-luteal phase, control ewes received serial saline injections, whereas test females (which also served as embryo donors) received either a single PMSG injection (1200 IU) or serial injections of FSH-P (total, 21 mg) or hMG (total, 1350 IU) over 3.5 d. These sheep were naturally mated and artificially inseminated (AI) in utero. Number of CL and transferable-quality embryos 5 d after AI was greater (P<0.05) in FSH-P-and hMG-treated donors than in PMSG-treated ewes. The lower number of transferable-quality embryos produced by PMSG-treated donors was attributed to a reduced (P<0.05) fertilization rate compared with that of the other treatment groups. There were no differences (P>0.05) in daily circulating estradiol-17beta and progesterone concentrations among the gonadotropin treatment groups. Gonadotropin-treated ewes demonstrated estrus approximately 24 h earlier than control ewes and, therefore, exhibited an accelerated estradiol-17beta surge and rise in circulating progesterone. Progesterone production in gonadotropin-treated ewes was also more variable than in the controls; this was due, in part, to premature luteal regression which occurred in 4 of 10 PMSG-, 3 of 10 FSH-P- and 6 of 10 hMG-treated ewes also given PGF2alpha. Ewes with prematurely regressing CL experienced transient luteal tissue development within 4 d of ovulation and produced no embryos. Overall results 1) demonstrate that serial administration of hMG induces multiple ovulations in sheep comparable to FSH-P, and 2) suggest that PGF2alpha treatment during ovulation induction adversely affects newly formed luteal tissue compromising subsequent embryo recovery.

Journal Article↗

PubMed2005

Neonatal handling and reproductive function in female rats.

Neonatal handling induces anovulatory estrous cycles and decreases sexual receptivity in female rats. The synchronous secretion of hormones from the gonads (estradiol (E2) and progesterone (P)), pituitary (luteinizing (LH) and follicle-stimulating (FSH) hormones) and hypothalamus (LH-releasing hormone (LHRH)) are essential for the reproductive functions in female rats. The present study aimed to describe the plasma levels of E2 and P throughout the estrous cycle and LH, FSH and prolactin (PRL) in the afternoon of the proestrus, and the LHRH content in the medial preoptic area (MPOA), median eminence (ME) and medial septal area (MSA) in the proestrus, in the neonatal handled rats. Wistar pup rats were handled for 1 min during the first 10 days after delivery (neonatal handled group) or left undisturbed (nonhandled group). When they reached adulthood, blood samples were collected through a jugular cannula and the MPOA, ME and MSA were microdissected. Plasma levels of the hormones and the content of LHRH were determined by RIA. The number of oocytes counted in the morning of the estrus day in the handled rats was significantly lower than in the nonhandled ones. Neonatal handling reduces E2 levels only on the proestrus day while P levels decreased in metestrus and estrus. Handled females also showed reduced plasma levels of LH, FSH and PRL in the afternoon of the proestrus. The LHRH content in the MPOA was significantly higher than in the nonhandled group. The reduced secretion of E2, LH, FSH and LHRH on the proestrus day may explain the anovulatory estrous cycle in neonatal handled rats. The reduced secretion of PRL in the proestrus may be related to the decreased sexual receptiveness in handled females. In conclusion, early-life environmental stimulation can induce long-lasting effects on the hypothalamus-pituitary-gonad axis.

Animals↗

PubMed2006

Ovarian and endocrine responses to prostaglandin F2alpha (PGF2alpha) given at the expected time of the endogenous FSH peak at mid-cycle in ewes.

In the ewe, a rise in circulating concentrations of FSH preceding follicular wave emergence begins in the presence of growing follicles from a previous wave. We hypothesized that prostaglandin F(2alpha) (PGF(2alpha)) given at the time of an endogenous FSH peak in cyclic ewes would result in synchronous ovulation of follicles from two consecutive waves, increasing ovulation rate. Twelve Western White Face (WWF) ewes received a single i.m. injection of PGF(2alpha) (15 mg/ewe) at the expected time of a peak in FSH secretion, from Days 9 to 12 after ovulation. The mean ovulation rate after PGF(2alpha) treatment (2.3+/-0.3) did not differ (P>0.05) from the pre-treatment ovulation rate (1.7+/-0.1). Five ewes ovulated follicles from follicular waves emerging before and after PGF(2alpha) injection (3.0+/-0.6 ovulations/ewe) and seven ewes ovulated follicles only from a wave(s) emerging before PGF(2alpha) treatment (2.0+/-0.3 ovulations/ewe; P>0.05). The mean interval from PGF(2alpha) to emergence of the next follicular wave (1.0+/-0.4 and 4.0+/-0.0 d, respectively; P<0.001) and the interval from PGF(2alpha) treatment to the next FSH peak (0 and 3.5+/-0.4d, respectively; P<0.05) differed between the two groups. Six ewes ovulated after the onset of behavioral estrus, with a mean ovulation rate of 1.7+/-0.2, and six ewes ovulated both before and after the onset of estrus (3.0+/-0.5 ovulations/ewe; P<0.05). None of the ovulations that occurred before estrus resulted in corpora lutea (CL) with a full life span. At 24h before ovulation, follicles ovulating before or after the onset of estrus differed in size (4.1+/-0.3 or 5.5+/-0.4mm, respectively; P<0.05) and had distinctive echotextural characteristics. In conclusion, the administration of PGF(2alpha) at the expected time of an FSH peak at mid-cycle in ewes may alter the endogenous rhythm of FSH secretion and was not consistently followed by ovulation of follicles from two follicular waves. In non-prolific WWF ewes, PGF(2alpha)-induced luteolysis disrupted the normal distribution of the source of ovulatory follicles and may be associated with untimely follicular rupture and luteal inadequacy.

Animals↗

PubMed2000

Monitoring of estrous cycle of ewes by ram-seeking behavior.

For 6 years adult, non-synchronized Hampshire ewes (n=2,5,8,8,9 and 12) and rams (n=6,10,12,11,11 and 9) were maintained separately and released to contiguous pastures having in common a woven-wire fence about 80m long and 1.1m high. Natural estrous cycles were monitored daily by observations of ram-seeking behavior as defined as a ewe being persistent in staying at the common fence with attention focused on the ram to the virtual exclusion of grazing. Day 0 of the estrous cycle is the first day that ram-seeking is observed. One hundred and thirty four fence stays and 115 estrous cycles have been observed. For cycles falling within the normal range, the mean cycle duration (+/-SE) was 16.53+/-0.03 days. During the first four study years, a copulation test with an intact ram, carried out on a spot-check basis, indicated that all tested ewes showing ram-seeking, except one, were in estrus. Ram-seeking never occurred outside of the estrous period of the cycle. During the fifth year, daily copulation tests with an intact ram and daily observations for ram-seeking has indicated that estrus generally lasts about two days while ram-seeking lasts for one of these days, so that the two behaviors while overlapping are not coextensive. During the sixth year, daily copulation tests with a vasectomized ram showed again a partial coincidence of the two behaviors, but also that occasionally they appeared to have the same duration. It is concluded that the utilization of ram-seeking provides an alternative, practical means to monitor the estrous cycle.

Journal Article↗