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PubMed1986

Intracranial sites regulating the biphasic action of progesterone in estrogen-primed golden hamsters.

Diencephalic and mesencephalic neural sites regulating the biphasic effect of progesterone (P) were investigated using the hormone implantation technique in ovariectomized female golden hamsters primed with estrogen. Double barreled cannulae were implanted unilaterally and bilaterally in the medial preoptic area, anterior hypothalamus, ventromedial hypothalamus (VMH), central gray, or interpeduncular nucleus. Testing was conducted using a sequential paradigm; facilitation tests commenced after 44 h of estrogen priming. P-filled cannulae placed in the VMH region facilitated lordosis behavior in 42% and 60% of unilaterally and bilaterally implanted females, respectively. In the anterior hypothalamus, only P implants adjacent to the VMH area effectively promoted receptivity. Lordosis behavior was also observed in 20-36% of females with P implants in the medial preoptic area. P implants in central gray and interpeduncular nucleus regions had no significant facilitating effect on sexual behavior. Tests for inhibition occurred 24 h after facilitation testing and consisted of a pretest, followed by systemic P administration and a behavioral test 4-5 h later. During the pretest for inhibition, females that were receptive in the facilitation test attacked males more rapidly than previously nonreceptive animals and showed decrements in lordosis scores after systemic P delivery. This biphasic effect of P completely inhibited receptivity among several animals in the VMH group. Additional experiments, however, investigating the biphasic effect of P implants in the VMH suggested that the occurrence of copulation in the facilitation test may have been involved in mediating the subsequent increase in aggressive behavior and the suppression of sexual responsiveness in the inhibition test. Nevertheless, a final experiment showed that when P was implanted sequentially in the VMH, facilitation and, more importantly, a later reduction in lordosis behavioral scores occurred even when copulation was eliminated in the facilitation test. P implants in mesencephalic regions exerted no significant inhibitory effect on receptivity. These findings demonstrate that the biphasic action of P in the female hamster is regulated by nerve cells located in the diencephalon, especially in the VMH region.

Animals↗
PubMed1976

Prolactin and delayed pseudopregnancy in the rat.

In (RXU)F1 hybrid rats delayed pseudopregnancy was induced in three different ways: 1) by removal of all recent corporl lutea on day 2 of pseudopregnancy, 2) by removal of the in situ ovaries from ovarian graft-bearing animals on day 0 of pseudopregnancy, 3) by administration of 1 mg of ergocornine hydrogenmaleinate (ECO) on day 1 of pseudopregnancy. These procedures ended pseudopregnancy and in 50-60% of the animals a delayed pseudopregnancy with a duration of 6-15 days was observed after the experimental cycle. After sterile copulation two daily prolactin peaks were observed. Removal of the ovaries in situ (from ovarian graft-bearing animals) or of recently formed corpora lutea (from non-grafted animals) caused the disappearance of the prolactin peak at 19.00 h, without affecting the occurrence of the 03.00 h peak. The administration of ECO caused the disappearance of both prolactin peaks. Until the day of estrus prior to delayed pseudopregnancy there were no differences in prolactin concentrations at 03.00 or 19.00 h between animals which became delayed pseudopregnant and those which remained cyclic. In the latter animals the 03.00 h surges decreased slowly in the luteectomized and the ovariectomized animals and were no longer present 7-9 days after copulation. In animals becoming delayed pseudopregnant both prolactin peaks were present from day 0 of delayed pseudopregnancy onwards. Progesterone cencentrations during delayed pseudopregnancy were relatively low when delayed pseudopregnancy had a duration of 6-9 days. When delayed pseudopregnancy lasted 10 days or more normal progesterone values were found.

Animals↗
PubMed1977

Fusion and erosion of cell walls during confugation in the fussion yeast (Schizosaccharomyces pombe).

Conjugation in Schizosaccharomyces pombe was studied by transmission electron microscopy. Mural and nuclear events were scored from induction, the initial event, to meiosis I, the start of sporulation. These morphogenic markers were separately identifiable as flocculation, copulation, conjugation-tube formation, cross-wall formation, cross-wall erosion, conjugation-tube expansion, cytoplasmic fusion, de-differentiation of site of union, nuclear migration and karyogamy. The following were identified as new structural elements: sex hairs, which presumably mediate hydrogen bonding between cells during flocculation; crimp at the site of union; dark patch, which presumably serves as a leak-proof seal at the time of cross-wall erosion; suture, an electron-dense seam formed by the union of a copulant pair; and small electron-dense particles close to the site of wall erosion. No special structures on the cell wall could be identified as indicative of specific sites for potential copulatory activity. The discontinuity of the 2 cell walls at the site of union became so de-differentiated after fusion and erosion that it was no longer possible to pinpoint the site of union.

Ascomycota↗
PubMed2003

Auto-spermatophore extrusion in male crickets.

The reproductive cycle of the male cricket consists of the mating stage and the sexually refractory stage. The latter is further divided into the first refractory stage (RS1) from spermatophore extrusion in copulation to spermatophore preparation after copulation, and the second refractory stage (RS2) from spermatophore preparation to recommencement of a calling song. RS2 is time-fixed and unaffected by the female or by stress, hence RS2 is assumed to be controlled by the reproductive timer. Previously, we suggested that the timer is located in the terminal abdominal ganglion (TAG), because functional inactivation of the TAG by local cooling lengthened RS2 in proportion to cooling time. To obtain further evidence of timer localization and to examine the operation of the timer in dissected animals, we investigated the characteristics of auto-spermatophore extrusion, a phenomenon in which males eject the mature spermatophore themselves without any prior courtship. The occurrence of auto-spermatophore extrusion was 100% in dissected males with the TAG separated, compared to 1.7% in intact males. The time interval (SPaSE) between spermatophore preparation and auto-spermatophore extrusion was comparable to RS2 measured by the calling song. Spike recording from a genital motor neurone in the separated TAG indicated that burst discharge associated with auto-spermatophore extrusion occurred with a SPaSE comparable to RS2. Other efferent neurones, some of which were identified as dorsal unpaired median (DUM) neurones, showed a time-dependent spike frequency increase during SPaSE. These results strengthen our previous conclusion that the reproductive timer is located within the TAG, and demonstrate that the timer functions normally even when the TAG is separated from the central nervous system.

Action Potentials↗
PubMed1997

Nervous control of male sexual drive in the hermaphroditic snail

We studied the role of the prostate gland in determining the level of male sexual drive in the hermaphroditic pond snail Lymnaea stagnalis. Male sexual drive is high after a period of social isolation and decreases after copulation as a male. A positive correlation exists between the level of male sexual drive and the volume of the prostate gland. Like male sexual drive, the volume of the prostate gland increases during a period of social isolation and decreases after copulation as a male. Behavioural experiments demonstrated that animals with a lesion of the nerve that innervates the prostate gland (NP1) have a lower level of male sexual drive after social isolation than control animals. However, lesion of NP1 did not affect the increase in the volume of the prostate gland caused by social isolation. Extracellular recordings from NP1 in a semi-intact preparation show a change in firing pattern during an experimentally induced increase in prostate gland volume. The results indicate that NP1 serves as a nervous pathway for the male sexual drive. We propose a simple motivational model for male sexual behaviour in L. stagnalis in which the volume of the prostate gland sets the level of male sexual drive.

Journal Article↗
PubMed1992

Influence of melatonin on reproductive behavior in male rats.

The influence of melatonin on reproductive behavior was examined by administering it to pinealectomized male rats for 30 consecutive days. After the 30-d administration of melatonin or vehicle, each male rat was introduced into a female rat's cage on the day of proestrus and allowed to mate overnight. All rats administered the vehicle and the pinealectomized rats copulated; five of the twelve melatonin (8.0 mg/kg)-treated rats did not copulate. These findings suggest that melatonin inhibits the reproductive behavior of male rats.

Animals↗
PubMed1996

Collection of semen from marmoset monkeys (Callithrix jacchus) for experimental use by vaginal washing.

Assisted reproductive techniques make an important contribution to the conservation of endangered primate species. In our laboratories marmoset monkeys (Callithrix jacchus) are used as a model species for developing assisted reproductive technologies for New World primates. The studies require a reliable method for collecting functional sperm from these small animals. For this purpose a minimally invasive procedure, vaginal washing after natural mating, was evaluated for its suitability as a routine method of obtaining ejaculated sperm of high quality. The objective of the first series of tests was to identify a behavioural pattern which was easily discernible by the observer and provided a reliable indication that ejaculation had occurred. In a second series of tests the influence of length of separation of the male prior to copulation on the quality of the ejaculate was evaluated. Six adult ovariectomized and five adult intact females were used for vaginal washing, while their mates served as donors of ejaculates. Matings at specific times were achieved by separating the males from their females for a certain time period and subsequently introducing either their own mates or unfamiliar males to the females. After each observed mating vaginal washing was performed on the unsedated females. The seminal samples obtained were analysed for sperm concentration, the proportion of motile sperm and the proportion of live sperm. The results have shown (a) that ejaculation was indicated with a reliability of 86.1% by the behaviour of the female, who terminates a copulation by moving away from her partner; (b) that separation of the male for up to six days had no negative effect on the sperm quality; (c) that the sperm samples were of high quality. Vaginal washing after natural matings appears to be a practical, reliable and gentle method for routinely collecting ejaculates from marmoset monkeys and possibly other New World primates.

Animals↗
PubMed2004

Fine structure and function of the genital pore of the female of Intoshia variabili (Orthonectida).

The genital pore of the female of Intoshia variabili Aleksandrov et Sljusarev, 1992 is located on a transverse ring of non-ciliated cells. Before copulation it is occupied by 6-7 cells that develop in the epithelium and that for a time are beneath the surface. When fully developed, these cells contain many electron-dense granules and their apical surface is covered with numerous microvilli. After copulation the granules disappear and the apical surface becomes smooth. The cells still form a plug closing the opening. After one larva pushes the pore cells out and escapes, others follow.

Animals↗
PubMed1975

Changes in social organization during the breeding season of wild talapoin monkeys.

Two adjacent troops of talapoin monkeys were studied near Mbalmayo, Cameroon, during a predicted 3-month breeding season. Mating continued for just over 2 months. One troop began to mate at least 2 weeks before the other, suggesting that, though climatic changes were probably important, precise timing was mediated through some intra-troop social facilitation effect. Before the breeding season, adult males and females lived in separate sub-groups. Males began to move into female sub-groups before there was any sign of the perineal swellings characteristic of receptive talapoin females. Copulation occurred only with females with medium or large swellings, except towards the end of the season. It is probable that the majority of females were monoestrous. At the height of the mating period, females joined mainly male sub-groups, leaving their infants with the mainly female groups which also included a few males. Copulations were observed in both these types of sub-groups. Consort behaviour was not observed, males frequently returning to all-male sub-groups immediately after ejaculation. Intersexual grooming was not characteristic of sexual interactions. At the end of the season, adults were seen more frequently in groups of their own sex or with juveniles only, and there was some indication that increased aggressiveness by newly pregnant females might be partly responsible for this separation.

Age Factors↗
PubMed1980

Sexual dimorphism of the phallus in spotted hyaena (Crocuta crocuta).

The weight of the skinned phallus and the diameter of its shaft and glans did not differ significantly in the two sexes of spotted hyaena, but phallus length was greater in males. The urethra of the penis was surrounded by corpus spongiosum, while the urogenital canal of the clitoris was suspended beneath the erectile bodies in loose connective tissue, an arrangement compatible with dilatation of the canal during copulation and parturition. The average width of the phallic meatus in juvenile females exceeded that in males of any age and, in adults, the clitoridal meatus was > 10 times the width of the penile meatus. A robust retractor muscle situated dorsal to the urogenital canal further distinguished the clitoris from the penis; this muscle may play an important role in facilitating copulation.

Animals↗
PubMed1983

Studies on the vaginal plug of the Japanese greater horseshoe bat, Rhinolophus ferrumequinum nippon.

The vaginal plug of the Japanese greater horseshoe bat is composed of an outer, thick, hard and homogeneous layer originating from the stratum disjunctum of the vaginal mucosa and a thin, soft and opaque central core containing accidentally trapped dead spermatozoa. The vaginal plug appeared to be expelled just before or after ovulation in spring. Immediately after copulation in autumn, uterine spermatozoa were dead but few leucocytes were present. As time passes after copulation, however, the infiltration of leucocytes into the uterus increased gradually, and extensive leucocytic phagocytosis of dead spermatozoa occurred during hibernation.

Animals↗
PubMed1985

Observations on variability in LH release and fertility during oestrus in the domestic cat (Felis catus).

Hormonal changes, behaviour, ovulation and fertility were examined in response to coitus at two different times during oestrus in the female domestic cat housed in conditions of natural light (N = 13). On Day 2 or Day 4/5 of oestrus females were allowed 1 copulation in 15 min (single matings) or 2-3 copulations in 30 min (multiple matings). Plasma LH, oestradiol-17 beta and progesterone concentrations during the 24-h period after coitus were measured by radioimmunoassay; ovulation was assumed to have occurred if progesterone values were elevated 7-30 days after coitus. With the exception of 2 out of 3 animals receiving single matings on Day 2 of oestrus, all animals showed subsequent elevated progesterone values. Females receiving multiple matings had significantly greater releases of LH as measured by the area under the curve than those receiving single matings. There was significantly greater variability in the LH response of queens on Day 2 of oestrus compared to those on Day 4/5 for peak values and area under the curve; the only failure in release of LH was in queens on Day 2. Oestradiol levels did not differ significantly between Day 2 and Day 4/5 of oestrus. Progesterone values remained less than 1 ng/ml for 24 h after coitus. Both LH peak values and area under the curve were significantly greater for animals that became pregnant. There were also significant differences in coital behaviour between queens on Day 2 and those on Day 4/5 of oestrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Chlorpromazine inhibits the mitotic index, cell number, and formation of mouse blastocysts, and delays implantation of CBA mouse embryos.

Chlorpromazine, administered to pregnant CBA mice 56 h after copulation in single doses of 10 or 15 mg/kg bodyweight, inhibited the compaction of embryos, formation of blastocysts, and reduced the mitotic index and cell number of embryos 86 h after copulation but did not adversely influence their viability or induce structural chromosomal aberrations. Blastocyst formation was more severely affected than embryo compaction. When 86-h embryos were treated with chlorpromazine (10 or 15 mg/kg) and subsequently cultured for 120 h, there was delayed hatching from the zona pellucida, delayed attachment to the culture dish, outgrowth of the trophoblast and expansion of the inner cell mass. Mice treated identically and evaluated on the 18th day of gestation had fewer implanted embryos than did controls, and the fetuses weighed less. No resorptions, malformations or significant differences in intrauterine deaths were found. Chlorpromazine given in the same manner but at 0.5 mg/kg did not affect any of the aforementioned criteria. When 56 h embryos were cultured in vitro in the presence of 50 microM-chlorpromazine for a further 40 h, embryo compaction, blastocyst formation, the mitotic index and the total cell number were significantly reduced compared with controls. Blastocyst formation was again more severely affected than embryo compaction. The inhibition of embryo compaction, blastocyst formation, and reduction in mitotic index and cell number associated in this study with chlorpromazine in vivo and in vitro indicate that the drug inhibits the development of cleavage-stage embryos in the mouse. These effects might be mediated by antagonistic effects of calmodulin.

Animals↗
PubMed1991

Monitoring ovarian function and pregnancy by evaluating excretion of urinary oestrogen conjugates in semi-free-ranging Przewalski's horses (Equus przewalskii).

Immunoreactive urinary oestrogen conjugates were assessed in daily urine samples (approximately 5 samples/week) collected from 8 Przewalski's mares maintained under semi-free-ranging pasture conditions. The relative percentage contributions of immunoreactive urinary oestrogens during different reproductive stages (oestrus, luteal phase, early, mid- and late gestation) were determined using high-pressure liquid chromatography. In general, conjugated forms of oestrone (oestrone sulphate and oestrone glucuronide) were the major excreted immunoreactive oestrogens in nonpregnant and pregnant Przewalski's mares. Variations in urinary oestrogen conjugates indicated that the onset of oestrous cyclicity coincided with increasing daylengths, and the non-conception oestrous cycle was 24.1 +/- 0.7 days (n = 17) in duration. Most copulations (29/35, 82.9%) were observed between Day -4 and Day +1 from the preovulatory oestrogen conjugates peak (Day 0). Based on known copulation dates, the mean gestation length was 48.6 +/- 0.4 weeks (range 47.3-50.3 weeks). During pregnancy, urinary excretion of oestrogen conjugates increased approximately 300-fold over levels in non-pregnant mares, reaching peak concentrations by Week +24 (51% of gestation). These results demonstrate that longitudinal reproductive events, including oestrous cyclicity and pregnancy, can be monitored precisely by evaluating urinary oestrogen conjugates in samples from Przewalski's mares maintained under semi-free-ranging conditions.

Animals↗
PubMed1997

Fate and distribution of seminal plasma proteins in the genital tract of the female rat after natural mating.

This paper describes the distribution and fate of seminal plasma proteins in the rat female genital tract after insemination, using immunological detection in tissue sections and in fluids collected from different regions. The localization of seminal plasma proteins in the uterus and the vagina correlated with that of spermatozoa, suggesting that passive transport mechanisms operate in these regions. No seminal plasma proteins were detected in the oviduct, indicating that their presence is probably restricted to the uterine environment. Possible mechanisms for eliminating seminal plasma molecules after copulation include leakage from the uterus after relaxation of the cervical muscles and endocytosis by the endometrial cells. Large amounts of both vesicular and coagulating gland proteins were detected in the vagina of females at the time of cervical relaxation, indicating that the first mechanism of leakage from the uterus after cervical relaxation operates. Immunocytochemical procedures were used and seminal vesicle antigens were detected inside uterine epithelial cells, which indicates that endocytosis is also a mechanism for elimination of these molecules after copulation. Western blot results suggest proteolytic cleavage as a third mechanism. However, coagulating gland antigens are neither endocytosed nor cleaved, and their elimination takes place only by backflow to the vagina. The seminal plasma distribution in experimental situations in which sperm transport is altered was also studied. The implications of our findings for mechanisms of sperm transport in the female are discussed.

Animals↗
PubMed2004

The quantitative genetic basis of male mating behavior in Drosophila melanogaster.

Male mating behavior is an important component of fitness in Drosophila and displays segregating variation in natural populations. However, we know very little about the genes affecting naturally occurring variation in mating behavior, their effects, or their interactions. Here, we have mapped quantitative trait loci (QTL) affecting courtship occurrence, courtship latency, copulation occurrence, and copulation latency that segregate between a D. melanogaster strain selected for reduced male mating propensity (2b) and a standard wild-type strain (Oregon-R). Mating behavior was assessed in a population of 98 recombinant inbred lines derived from these two strains and QTL affecting mating behavior were mapped using composite interval mapping. We found four QTL affecting male mating behavior at cytological locations 1A;3E, 57C;57F, 72A;85F, and 96F;99A. We used deficiency complementation mapping to map the autosomal QTL with much higher resolution to five QTL at 56F5;56F8, 56F9;57A3, 70E1;71F4, 78C5;79A1, and 96F1;97B1. Quantitative complementation tests performed for 45 positional candidate genes within these intervals revealed 7 genes that failed to complement the QTL: eagle, 18 wheeler, Enhancer of split, Polycomb, spermatocyte arrest, l(2)05510, and l(2)k02206. None of these genes have been previously implicated in mating behavior, demonstrating that quantitative analysis of subtle variants can reveal novel pleiotropic effects of key developmental loci on behavior.

Animals↗
PubMed2006

The genetic basis of prezygotic reproductive isolation between Drosophila santomea and D. yakuba due to mating preference.

Sexual isolating mechanisms that act before fertilization are often considered the most important genetic barriers leading to speciation in animals. While progress has been made toward understanding the genetic basis of the postzygotic isolating mechanisms of hybrid sterility and inviability, little is known about the genetic basis of prezygotic sexual isolation. Here, we map quantitative trait loci (QTL) contributing to prezygotic reproductive isolation between the sibling species Drosophila santomea and D. yakuba. We mapped at least three QTL affecting discrimination of D. santomea females against D. yakuba males: one X-linked and one autosomal QTL affected the likelihood of copulation, and a second X chromosome QTL affected copulation latency. Three autosomal QTL also affected mating success of D. yakuba males with D. santomea. No epistasis was detected between QTL affecting sexual isolation. The QTL do not overlap between males and females and are not disproportionately concentrated on the X chromosome. There was some overlap in map locations of QTL affecting sexual isolation between D. santomea and D. yakuba with QTL affecting sexual isolation between D. simulans and D. mauritiana and with QTL affecting differences in pigmentation between D. santomea and D. yakuba. Future high-resolution mapping and, ultimately, positional cloning, will reveal whether these traits do indeed have a common genetic basis.

Animals↗
PubMed1978

[Reproductive lifespan and reproductive performance in SPF C3H mice: the onset of reproductive life and production efficiency (author's transl)].

To improve the production system, the onset and the termination of reproductive life of C3Hf/HeMsNrs mice mated immediately after weaning and reared for 400 days of life, were studied. From weaning females mated with a full grown male (group A), the first litter was obtained at a mean age of 47 days, suggesting the first copulation at 26 days of age. The age of males at the first copulation was estimated to be at 44 days of age from the age giving the first litters in weanling males mated with weanling (group B) and full grown (group C) females. The sex ratio of litters delivered by young dams tended to be excess in males. The reproductive performance of dams in later life was not affected by the parturition in earlier age. The production efficiency with weaned youngs per pair during the first 200 days after mating was the highest in group A. It was found from these results that the C3H females attained their sexual maturity at 5 to 6 days after weaning, being available for breeding without any deletion in reproductive performance.

Age Factors↗