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PubMed1982

[Gonadal function in the rat exposed to a high intensity electric field of 50 Hz].

The effects of 50 Hz AC electric field of high intensity (100 kV/m) have been studied on the reproductive system of male rats exposed acutely (30 minutes a day) or chronically (8 hours a day) for up to 48 days. Groups of controls were studied simultaneously. Weight of the testicles, sperm viability, number of copulations, pregnancies, foetal implantations and reabsorptions as well as macro and microscopic anatomy have been investigated after mate with unexposed females. For acutely exposed animals, the number of copulations and fertility appeared lower than during chronic exposure. On the contrary, no changes were observed in sperm viability, morphology and in the others parameters under study. During chronic exposure no changes of any of the parameters analyzed occurred. However, in both modes of exposure the weight of the offsprings was about 10% lower than in controls. We conclude that exposure of male animals to extremely high electric field does not cause any damage to the reproductive system.

Animals↗
PubMed1995

Appetitive as well as consummatory aspects of male sexual behavior in quail are activated by androgens and estrogens.

Appetitive male sexual behavior was measured in male quail with the use of a learned social proximity procedure that quantified the time spent by a male in front of a window providing a view of a female that was subsequently released into the cage, providing an opportunity for copulation. The learned response is not acquired by castrated males but can be acquired when castrates are treated with testosterone (T) or with the synthetic estrogen diethylstilbestrol or with the endogenous estrogen 17 beta-estradiol. Only birds that become sexually active acquire the response. Conversely, birds in which the consummatory copulatory behavior is disrupted by treatment with the antiestrogen tamoxifen lose the anticipatory response. These results demonstrate that appetitive sexual behavior is, like copulation, activated by T and by estrogens. This suggests that intracerebral aromatization of T also plays a critical role in the activation of this behavior.

Androgens↗
PubMed1995

Effects of sexual conditioning of devaluing the US through satiation.

Male Japanese quail were conditioned to approach a visual CS that predicted an opportunity to copulate with a female quail. Subsequently the subjects were tested in both non-reinforced and reinforced test trials while sexually satiated and sexually deprived. In the satiation condition the sexual US was devalued by allowing the male subjects to copulate repeatedly with female birds just prior to testing. The subjects displayed significantly less approach to the CS when sexually satiated than when sexually deprived. These results are compatible with a mechanism in which performance of Pavlovian sexual approach conditioning is mediated by activation of a memorial representation of the US.

Animals↗
PubMed1994

Effects of intrathecal administration of adrenergic agonists on the frequency of copulatory pelvic thrusting of the male rat.

The effects of the intrathecal perispinal administration of adrenergic agonists on the characteristics of frequency, duration, and vigor of pelvic thrusting displayed by male rats during copulation was assessed by an accelerometric technique. A different dose of one drug (noradrenaline, clonidine or isoproterenol) and saline as control was administered at the lumbosacral level of the spinal cord to sexually active male rats in tests of sexual behavior performed at weekly intervals. The intrathecal administration of noradrenaline (alpha-adrenoceptor agonist) increased the frequency of pelvic thrusting in mount and intromission responses, whereas both the alpha 2-adrenoceptor agonist clonidine (25 micrograms) and the beta-adrenoceptor agonist isoproterenol (40 micrograms) reduced the frequency of pelvic thrusting in these responses as compared to values obtained under the intrathecal administration of saline. On the other hand, the duration of the thrusting trains and the potency or vigor of pelvic thrusting in mounts and intromissions did not differ from values obtained under saline treatment. These findings indicate a possible participation of noradrenaline in the modulation of the spinal mechanisms involved in the generation of rhythmic pelvic thrusting performed by the male rat during copulation.

Adrenergic Agonists↗
PubMed1998

Are Eulemur species pair-bonded? Social organization and mating strategies in Eulemur fulvus rufus from 1988-1995 in southeast Madagascar.

Strong social relationships have been reported between adult male and female prosimian primates in the genera Eulemur and Varecia and have been referred to as "pair-bonding." It has been hypothesized that females benefit from these affiliative relationships with an adult male by having protection against infanticidal males, implying that the male member of the dyad also is the father of her offspring. I evaluated this hypothesis and whether or not the term pair-bond was appropriate by using field data collected on two groups of Eulemur fulvus rufus in southeastern Madagascar. Four predictions were tested: 1) male-female dyads will be stable throughout the year, 2) male-female dyads will be more prevalent during the mating season, and/or the birth season when infants would be most vulnerable to infanticide, 3) females should copulate either exclusively or most often with their male dyad partner than with other males during the mating and/or birth season, and 4) rates of aggression will be higher between males or between females and males who are not their dyad partner. Predictions 1, 2, and 3 were not supported and Prediction 4 was only partially supported. Adult male-female dyads however, were more prominent in feeding contexts during the mating season and food scarcity periods. Most aggression occurred during feeding between males and nondyad group members. Since female feeding rates were often higher when feeding near male dyad partners, adult male-female dyads may serve as a way of increasing foraging efficiency for the female, which in turn may influence reproductive success. All males who were dyad partners also copulated first and more frequently with all females. It is suggested that "dyad" is a better descriptive term than pair-bonding for the social patterns observed since dyads were comprised of same-sex individuals, were temporary, and did not exclusively serve a reproductive function.

Aggression↗
PubMed1997

Axial orthogonal fiber reinforcement in the penis of the nine-banded armadillo (Dasypus novemcinctus).

Examination of histological sections from flaccid and artificially erected nine-banded armadillo (Dasypus novemcinctus) penises confirms that the mammalian corpus cavernosum is the first known biological hydrostat reinforced by collagen fibers arranged at 0 degree and 90 degrees to its long axis. The morphology of this axial orthogonal fiber array affects the mechanical behavior of mammalian penises during erection and copulation. Specifically, the axial orthogonal array gives the erect penis a reproducible shape, maximum size and resistance to tensile, compressive, and bending forces. These features are more appropriate for the mechanical regime associated with copulation than those found in structures reinforced by crossed-helical fibers, although the axial orthogonal array also gives the corpus cavernosum a tendency to fail by kinking. Crimped collagen fibers in the flaccid array as well as three-dimensional folding of the wall in the flaccid corpus cavernosum allow the structure to expand during erection.

Anatomy, Artistic↗
PubMed1997

Steroid excretion during the ovarian cycle in captive and wild muriquis, Brachyteles arachnoides.

Urine, feces, and copulation frequency were collected from two captive muriqui females, Brachyteles arachnoides, at the Centro de Primatologia do Rio de Janeiro following the resumption of postpartum ovarian cycles. Fecal steroid profiles from seven wild muriqui females at the Estação Biologica de Caratinga, Minas Gerais, Brazil, were compared to the captive females to determine the approximate patterns of steroid excretion relative to the urinary LH peak. Hormonal profiles from one of the captive female muriquis revealed a discrete urinary LH peak. For this female, fecal progesterone increased on the same day as the urinary LH peak, while fecal estradiol increased 6 days later and urinary steroids increased 5 days later. For both captive females, the onset of fecal progesterone increase was preceded by the onset of copulations, which occurred during at least a 5-day period. The complete fecal hormonal profiles of the one captive female for which continuos data were available were similar to those found in wild muriqui monkeys, with the onset of an increase in sustained progesterone levels occurring several days prior to the onset of sustained estradiol increase. These patterns suggest that fecal progesterone may be excreted rapidly in this species. The onset of sustained increase in fecal progesterone levels, together with the consistent delay in the onset of the sustained increase in estradiol, may provide the best indicators of the periovulatory period for muriqui females.

Animals↗
PubMed1997

Special relationships instead of female dominance for redfronted lemurs, Eulemur fulvus rufus.

Most lemurs yet studied in detail exhibit some mode of adult female social dominance over males. The known exception, a brown lemur subspecies known as rufous or redfronted lemurs (Eulemur fulvus rufus), forms multimale-multifemale social groups within which unambiguous dominance relations are not observed among adults. Resting groups of redfronted lemurs consistently include huddling adult male-female pairs whose males selectively scentmark and rub their heads in the scentmarks of their female huddling partners. Quantitative observations confirmed that some of these male-female pairs maintain special relationships satisfying all criteria originally developed in research on cercopithecine monkeys. Observations before, during, and after mating season, intergroup encounters, male transfers, and changes in male-female affiliations illuminated developmental and functional aspects of male-female partnerships. Each adult female in two semi-free-ranging study groups shared high rates of association, grooming, and agonistic support and low rates of agonistic interaction with one unrelated or distantly related adult male partner. Such affinity characterized small proportions of adult male-female relationships. Several males directed not only support but also aggression toward adult females with whom they sought to affiliate. All bonded males sought to copulate with their partners, and some appeared to ignore estrus in nonpartners. All females accepted copulation attempts from partners and some seemed to prefer their partners as mates. Partial synchronization of brief estrus periods together with concealed ovulation appeared to minimize chances for polygynous mating. Results support the view that the male-female pair is the fundamental social unit of E. fulvus and suggest that female partnership with individual males obviates dominance behavior, including female dominance, in this lemurid primate.

Agonistic Behavior↗
PubMed2004

Genotyping from semen of wild Japanese macaques (Macaca fuscata).

The noninvasive collection of animal cells is crucial for DNA analyses in wild populations that cannot be disturbed by capture. We describe the collection of 68 semen samples following copulation and masturbation events in wild habituated and nonhabituated troops of Japanese macaques on the protected island of Yakushima. We used this DNA to amplify 390 base pairs (bp) of the mitochondrial DNA control region in 16 individuals from eight troops, and found a monomorphic pattern in agreement with the low variability imposed by geographic isolation and female philopatry. We also amplified two microsatellite loci from samples collected after the resident males of a focal troop had copulated with different females. We found several different allele combinations in samples collected after the observed mating of a single male, indicating the presence of contaminant DNA, presumably from males that had previously mated with the same female. This discovery made it impossible to assign a given sample to a specific male except when the samples were recovered after masturbation events. Thus, it was not possible to test for kinship or estimate allele frequencies from the semen samples. The mixing of semen, and the pattern of sample collection observed in morphologically identified individuals support the notion that strong mating and sperm competition exists among resident and nonresident males.

Animals↗
PubMed2005

Behavioral indicators of ovarian phase in white-faced capuchins (Cebus capucinus).

In many primate species, conspicuous behavioral and/or morphological changes are indicators of the fertile phase of the female cycle. However, several primate species, such as the white-faced capuchin, lack these cues. This is referred to as "concealed ovulation," and is argued to be a reproductive strategy that confuses paternity and lowers the risk of infanticide. We studied 10 adult female white-faced capuchins in Santa Rosa National Park, Costa Rica, from January to June 2002. We determined their ovarian cycling patterns by analyzing fecal ovarian hormones, and compared simultaneously collected behavioral data to determine which, if any, cues females use to signal their fertile phases. We found that four females cycled during the study period but ceased to cycle without becoming pregnant. We considered several explanations for the lack of conception during our study, including reproductive seasonality. We found that female C. capucinus showed only small increases in rates of affiliative/proceptive behaviors directed toward adult males during their periovulatory phases. The best indicator of cycle phase was a significant increase in male affiliative behaviors (e.g., following and grooming bouts) and sexual behaviors (e.g., copulations and courtship displays) directed toward females during the periovulatory phase compared to the nonovulatory phase. Our finding that females exhibit little proceptive behavior, but that copulations and male courtship are nonetheless concentrated in periovulatory phases suggests that even though females do not provide behavioral and morphological cues to ovulation, males are still able to detect it. Infanticide occurs with some frequency in these monkeys, and there is evidence for postconceptive mating as a female strategy to lower risk of infanticide via paternity confusion. However, despite this occurrence of nonconceptive mating and the absence of female cues to ovulation, truly concealed ovulation does not appear to be characteristic of this study population of white-faced capuchins.

Animals↗
PubMed2006

What Hanuman langur males know about female reproductive status.

In species with a high risk of infanticide, a conflict of interest exists between the sexes over the amount of paternity information that is available to males. While females are expected to keep males unaware of their reproductive status in order to confuse paternity, selection should favor those male traits that enhance the males' assessment of female status and consequently of paternity probability. In Hanuman langurs (Semnopithecus entellus), a species that is extremely vulnerable to infanticide, females have been shown to successfully conceal the exact timing of ovulation from males--perhaps because they exhibit no sexual swelling and mate during all reproductive phases, including gestation. Nevertheless, it remains unclear whether males have hitherto unrecognized information about females' reproductive condition on a broader level that could still enhance male reproductive success. We investigated male assessment of female reproductive states in a population of wild Hanuman langurs as indicated by changes in male behavior, such as rates of copulations, anogenital inspections, and consortships, in relation to different female receptive periods (pregnant, fertile-nonconceptional, and conceptional). Our data indicate that males were able to discern qualitatively distinct reproductive states. Males were more interested in fertile than pregnant females, as indicated by higher copulation rates. Based on consortships, males distinguished fertile from nonfertile phases, as well as fertile, nonconceptional receptive periods from conceptional ones. Hanuman langur males are thus not as unaware of female reproductive condition as previously thought, supporting the idea of an ongoing battle of the sexes over paternity information. However, granting some knowledge while at the same time concealing the exact day of ovulation may also reflect a pure female strategy of balancing paternity concentration with paternity confusion, which is the most likely strategy in this system with high infanticide risk and male defense of infants.

Animals↗
PubMed2004

Reproductive toxicity assessment of lasofoxifene, a selective estrogen receptor modulator (SERM), in male rats.

BACKGROUND: Lasofoxifene is a nonsteroidal selective estrogen receptor modulator (SERM) with greater than 100-fold selectivity against all other steroid receptors and is a potentially superior treatment for postmenopausal osteoporosis. The purpose of this study was to evaluate the effects of lasofoxifene on male reproduction in rats in light of the known effects of estrogen modulating compounds on male reproductive ability. METHODS: Lasofoxifene was administered to adult male rats at doses of 0.1, 1, 10, and 100 mg/kg for 66-70 consecutive days. After 28 days of dosing, male rats were cohabited with untreated female rats. Female rats were euthanized on gestation day 14 and a uterine examination was carried out for evaluation of reproductive parameters and embryo viability. Male rats were euthanized after 66-70 days of dosing and epididymal sperm motility and concentration were assayed. The testes, epididymides, prostate, and seminal vesicles were weighed and microscopically examined. RESULTS: The duration of cohabitation was increased for 100 mg/kg males by 0.7 days. The number of males copulating and the number of implantation sites produced per copulation were reduced in the 10 and 100 mg/kg groups. Weights of the seminal vesicles and epididymides were reduced for all groups, although the testes weight and epididymal sperm motility and concentration were not affected by treatment. There were no microscopic findings in the male reproductive tissues. CONCLUSION: The changes in male fertility and reproductive tissue weights after exposure to lasofoxifene are consistent with those previously described for estrogen receptor-modulating compounds.

Animals↗
PubMed1983

Rooting and the development of male sexual behavior in two inbred mouse strains.

The sexual development of C57BL 6/J and SEC/IReJ male mice was studied during twice-weekly pairings with estrus females from 5 weeks of age. SEC were far slower to begin copulating than C57 and their responses to the female included a much higher frequency of rooting. Rooting, where the male's snout is pushed below the female's flank and jerked upwards, declines over tests as the full copulatory pattern develops. SEC also spent a higher proportion of their time in close contact with the female and groomed her more than C57. Both strains showed more rapid development of copulation if testing was delayed until 10 weeks of age, especially if they had exposure to female scent during this maturation period. The frequency of rooting and the speed of development are inversely related in these strains, but in segregating hybrid populations no such relationship is maintained. It is argued that the slowness of SEC's development cannot be ascribed to low sexual motivation. The significance of rooting remains obscure, but it seems possible that it may represent an aspect of exploratory behavior that is highly developed in SEC and some other strains.

Animals↗
PubMed2005

Continuous male presence required for fertilization in captive painted dragons, Ctenophorus pictus.

Understanding proximate determinants of reproductive events is an important issue for many biologists. In the present paper, we show that follicular recruitment and fertilization are dependent on male stimuli in long-term captive female painted dragon lizards, Ctenophorus pictus. Hibernated females kept separated from males did not initiate reproduction, despite visual contact with displaying males and repeated copulation attempts. Follicular stimulating hormone stimulated ovarian growth and female receptivity, but did not result in successful fertilization of eggs, despite repeated copulations. When housed continuously together with males, however, follicle recruitment and fertilization were achieved. Thus, not only ovarian growth, but also fertilization, is dependent on male stimuli.

Animals↗
PubMed2006

Right-handed penises of the earwig Labidura riparia (Insecta, Dermaptera, Labiduridae): evolutionary relationships between structural and behavioral asymmetries.

The number of penises vary in the insect suborder Forficulina (order Dermaptera; earwigs). Males of the families Diplatyidae, Pigidicranidae, Anisolabididae, Apachyidae, and Labiduridae have two penises (right and left), while those of the Spongipohridae, Chelisochidae, and Forficulidae have a single penis. The proposed phylogenetic relationships among these families suggest that the single-penis families evolved from an ancestor possessing two penises. To date, examinations of double-penis earwig species have found that only a single penis is used per single copulation. These diversities in structural and behavioral aspects of genitalia raises the following intriguing questions: How are the two penises used? Why did a penis degenerate in several earwig families, and which one was lost? To address these questions, structural and behavioral asymmetries were examined in detail for a representative species Labidura riparia (Labiduridae). Although there was no detectable morphological differentiation between the right and left penises, male L. riparia predominantly used the right one for insemination. This significant "right-handedness" developed without any experience of mating and was also manifested in the resting postures of the two penises when not engaged in copulation. However, surgical ablation of the right penis did not influence the insemination capacity of males. In wild-caught males, only about 10% were left-handed; within this group, abnormalities were frequently observed in the right penis. These lines of evidence indicate that the left penis is merely a spare intromittent organ, which most L. riparia males are likely never to use. Additional observations of five species of single-penis families revealed that the left penis degenerated in the common ancestor of this group. Considering the proposed sister relationship between the Labiduridae and the single-penis families, it is possible that such behavioral asymmetries in penis' use, as observed in L. riparia, are parental to the evolutionary degeneration of the infrequently used left penis.

Animals↗
PubMed1977

Fine structure and role in behavior of sensilla on the terminalia of Aedes aegypti (L.) (Diptera: Culicidae).

The terminalia of male and female Aedes aegypti (L.) bear numerous hairs of various shapes and lengths, all of which are mechanoreceptors. Each hair is innervated by one bipolar neuron which contains ciliary rootlets, two basal bodies, and a region assuming the structure of a non-motile cilium. At the distal tip of the dendrite is a tubular body, a characteristic of cuticular mechanoreceptors. Covering the outer dendritic segment is a cuticular sheath which ends proximally in a net-like felt-work and distally attaches to the hair base. Each hair sensillum has two sheath cells. Presumed efferent fibers are associated with the sheath cells. On the insula of the female terminalia are a few campaniform sensilla, the domes of which are raised into small pegs. The sensilla on the terminalia function in copulation and oviposition and probably in warning. A sequence of neurological events is traced for copulation an oviposition. Other cuticular structures, viz., scales, microtrichia, acanthae, and aedeagal spines, which occur on the terminalia are not innervated.

Aedes↗
PubMed1986

Maternal administration of cyclophosphamide induces chromosomal aberrations and inhibits cell number, histone synthesis, and DNA synthesis in preimplantation mouse embryos.

The effects of cyclophosphamide (CPA), administered to pregnant inbred CBA/Ca mice 60 h after copulation, on cell number, mitotic index, chromosome structure, histone synthesis, and DNA synthesis of 84-h blastocysts, and the subsequent development of these blastocysts cultured for a further 120 h in vitro are described. Cyclophosphamide 4, 20, and 40 mg/kg significantly increased the number of chromosomally aberrant cells, chromosomal aberrations, and chromosome breaks in the blastocysts. Chromosomal rearrangements were significantly increased in the CPA 20 and 40-mg/kg treated groups, and in the 40-mg/kg group the number of cells with ring chromosomes was significantly increased. Histone synthesis and DNA synthesis were significantly inhibited in the CPA 20 and 40-mg/kg treated groups. Blastocyst cell number in each of the treated groups was less than the controls. On subsequent culture in vitro, significantly fewer embryos in the CPA 20 and 40-mg/kg groups hatched, attached, developed trophoblast outgrowths, and expanded their inner cell masses. However, the differentiation of inner cell mass into ectoderm and endoderm was impaired by all three doses of the drug. These results demonstrate that CPA administered to pregnant mice 60 h after copulation has a clastogenic effect and interferes with synthesis of DNA and histones in the preimplantation embryo, and that the drug inhibits the subsequent development and differentiation of these embryos. Cytogenetic analysis of preimplantation embryos might be a useful adjunct to the existing methods in the evaluation of the embryotoxicity of drugs and chemicals.

Animals↗
PubMed1997

Variation in sperm precedence during mating in male flies, Dryomyza anilis

To understand how individual differences in fertilization success arises in the fly Dryomyza anilisvariation in sperm precedence between and within males was studied. In D. anilisa mating consists of a copulation followed by tapping sequences during which the male taps the external genitalia of the female. These tapping sequences increase last male sperm precedence. Each male in the experiment was repeatedly mated with a set of females. In the first treatment, mating was interrupted after the male had an intromission. In the second treatment, the male was allowed to perform five tapping sequences after an intromission. In the third treatment, the male was allowed to perform an unlimited number of tapping sequences after an intromission until interrupted by female resistance. There were large differences between males in all three treatments as shown by the 95% confidence limits of the mean fertilization success. Repeatabilities of mating time and the number of tapping movements per tapping sequence were high indicating clear differences between males in these components of mating behaviour. Within individual males, the more tappings per sequence, the higher the fertilization success. In matings with an unlimited number of tapping sequences, fertilization success depended on female resistance. Within-male variation in fertilization success was higher in matings with an unlimited number of tapping sequences than in matings interrupted after a copulation. Several components of male mating behaviour thus contribute to the variation in sperm precedence in D. anilisFemale behaviour, in particular, resistance of tapping movements, can also increase variation in sperm precedence.

Journal Article↗