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Sperm Number (sperm + number)
Selected AbstractsInvestment in Mate Guarding May Compensate for Constraints on Ejaculate Production in the Cricket Gryllodes sigillatusETHOLOGY, Issue 12 2001Philip W. Bateman Although there is a corpus of evidence that females of many taxa are choosy about males, there is less information on how males may react to females of different ,quality' (i.e. potential fecundity). The cricket Gryllodes sigillatus shows distinct mate guarding behaviour. We examined how long males mate guard females of different sizes (reflecting egg load and potential fecundity). We also examined the sperm number in ampullae donated to females of different sizes to see if males make a concomitant difference in investment in ejaculate. We also examined mate-guarding behaviour and ejaculate size of males mated to virgin and nonvirgin females of the same size to see if males equate size with increased age and increased likelihood of mating (increased sperm competition). The results showed that males mate guard larger females for longer but make no difference in ejaculate investment between sizes of female. Males make no significant difference in mate guarding investment or ejaculate investment between virgins and nonvirgins of the same size. There is evidence that other species of crickets do alter their ejaculate depending on the female size and mating history, but have less distinct guarding behaviour. We suggest that mate-guarding investment in G. sigillatus may serve a similar function to that of ejaculate investment in other crickets. [source] Adverse trends in male reproductive health: we may have reached a crucial ,tipping point'INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2008A.-M. Andersson Summary Healthy men produce an enormous number of sperms, far more than necessary for conception. However, several studies suggest that semen samples where the concentration of sperms is below 40 mill/mL may be associated with longer time to pregnancy or even subfertility, and specimens where the concentration of sperms is below 15 mill/mL may carry a high risk of infertility. Historic data from the 1940s show that the bulk of young men at that time had sperm counts far above 40 mill/mL with averages higher than 100 mill/mL. However, recent surveillance studies of young men from the general populations of young men in Northern Europe show that semen quality is much poorer. In Denmark approximately 40 percent of the men have now sperm counts below 40 mill/mL. A simulation assuming that average sperm count had declined from 100 mill/mL in ,old times' to a current level close to 40 mill/mL indicated that the first decline in average sperm number of 20,40 mill/mL might not have had much effect on pregnancy rates, as the majority of men would still have had counts far above the threshold value. However, due to the assumed decline in semen quality, the sperm counts of the majority of 20 year old European men are now so low that we may be close to the crucial tipping point of 40 mill/mL spermatozoa. Consequently, we must face the possibility of more infertile couples and lower fertility rates in the future. [source] Geographic variation in sperm traits reflects predation risk and natural rates of multiple paternity in the guppyJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2010K. E. ELGEE Abstract Guppies (Poecilia reticulata) are models for understanding the interplay between natural and sexual selection. In particular, predation has been implicated as a major force affecting female sexual preferences, male mating tactics and the level of sperm competition. When predation is high, females typically reduce their preferences for showy males and engage more in antipredator behaviours, whereas males exploit these changes by switching from sexual displays to forced matings. These patterns are thought to account for the relatively high levels of multiple paternity in high-predation populations compared to low-predation populations. Here, we assess the possible evolutionary consequences of these patterns by asking whether variation in sperm traits reflect differences in predation intensity among four pairs of Trinidadian populations: four that experience relatively low levels of predation from a gape-limited predator and four that experience relatively high levels of predation from a variety of piscivores. We found that males in high-predation populations had faster swimming sperm with longer midpieces compared to males in low-predation populations. However, we found no differences among males in high- and low-predation populations with respect to sperm number, sperm head length, flagellum length and total sperm length. [source] Male body size predicts sperm number in the mandarinfishJOURNAL OF ZOOLOGY, Issue 3 2010M. B. Rasotto Abstract Theory predicts that, in species with non-resource-based mating systems, female preference for male sexual traits might be selected to ensure higher levels of fertility. Accordingly, secondary sexual traits used by females to assess males are expected to covary with ejaculate size and/or quality transferred during copulation, and female fecundity should be directly linked to mating with more attractive males. To date, direct tests of this hypothesis have been performed on internal fertilizing species, where several factors, such as for instance sperm competition, cryptic female choice, male parasite load, may affect ejaculate characteristics and female fecundity. Here, we used as a model the mandarinfish Synchiropus splendidus a small pelagic spawner where males only provide females with ejaculates and sperm competition does not occur. Males are significantly larger than females and we experimentally demonstrated that females prefer larger males. In addition, by collecting gametes from 67 natural spawning events, we attained a measure of the number of eggs and sperm released in each spawning event and the fertilization rates. The mean number of gametes produced positively correlates with body size in both sexes. Males do not regulate sperm number according to egg number and/or female body size. Fertilization success is significantly related to the mean number of sperm released but not directly to male body size. These findings, despite not fully accomplishing theoretical expectation, suggest that larger and more fecund females may suffer sperm limitation in mating with smaller males. In addition, our results have possible implications for the aquarium fishery of this species, which targets large males. [source] Mammalian sperm quality and aromatase expressionMICROSCOPY RESEARCH AND TECHNIQUE, Issue 8 2009Serge Carreau Abstract In most mammalian species the aromatase is encoded by a single gene (cyp19), which contains 18 exons, 9 of them being translated. In adult rats, together with Leydig cells germ cells represent an additional source of estrogens. The amount of P450arom transcript is threefold higher in pachytene spermatocytes compared to younger cells (spermatogonia-preleptotene spermatocyte) or round spermatids; conversely, aromatase activity is more intense in haploid cells. In man besides Leydig cells, we have shown the presence of a biologically active aromatase and of estrogen receptors (ER, and ERß) in immature germ cells and ejaculated spermatozoa. Concerning aromatase, a 30% decrease of the amount of mRNA is observed in immotile compared to motile sperm fraction from the same sample; moreover, the aromatase activity is diminished. We have amplified aromatase mRNA by RT-real time PCR in spermatozoa from asthenospermic, teratospermic, and asthenoteratospermic men and recorded respectively 44, 52, and 67% decreases of the amount of transcripts as compared to controls. Statistical analyses between the sperm morphology and the aromatase/GAPDH ratio have revealed a high degree of correlation (r = ,0.64) with the percentage of abnormal spermatozoa (especially microcephaly and acrosome malformations). Alterations of sperm number and motility have been described in men genetically deficient in aromatase, which together with our data, suggest a likely role for aromatase/estrogens in the acquisition of sperm motility. Therefore besides gonadotrophins and testosterone, estrogens produced locally should be considered as a physiologically relevant hormone involved in the regulation of mammalian spermatogenesis. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc. [source] Impaired sexual behavior in male mice deficient for the ,1,3 N -Acetylglucosaminyltransferase-I geneMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 5 2008Franziska Biellmann Abstract The ,1,3 N -acetylglucosaminyltransferase-1 (B3gnt1) gene encodes a poly- N -acetyllactosamine synthase which can initiate and extend poly- N -acetyllactosamine chains [Gal(,1,4)GlcNAc (,1,3)n]. Previous investigations with heterozygous and homozygous null mice for this gene have revealed the importance of poly- N -acetyllactosamine chains for the formation of olfactory axon connections with the olfactory bulb and the migration of gonadotropin releasing hormone neurons to the hypothalamus. The possible long-term effects of these developmental defects, however, has not yet been studied. Here we have examined a reproductive phenotype observed in B3gnt1 -null mice. Whereas the B3gnt1 null females were fertile, the B3gnt1 null males were not able to sire litters at the expected rate when mated to either wildtype or B3gnt1 -null females. We assessed male sexual behavior as well as male reproduction parameters such as testes size, spermatogenesis, sperm number, morphology, and the development of early embryos in order to identify the source of a reduced rate of reproduction. Our findings show that the B3gnt1 null male reproductive organs were functional and could not account for the lower rate at which they produced offspring with wildtype conspecifics. Hence, we propose that the phenotype observed resulted from an impaired sexual response to female mating partners. Mol. Reprod. Dev. 75: 699,706, 2008. © 2007 Wiley-Liss, Inc. [source] Intraperitoneal Insemination in Mammals: A ReviewREPRODUCTION IN DOMESTIC ANIMALS, Issue 2 2002JL Yaniz Contents This review focuses on factors associated with the development of intraperitoneal insemination in mammals. Findings to date indicate that fertility improves as the sperm cell concentration rises, but that the optimal sperm number differs in each species. Sperm washing before intraperitoneal insemination favours fertility. Peritoneal fluid shows a variable effect on spermatozoa, depending on the hormonal status of the female. The optimal time for insemination appears to be just prior to ovulation. The technique may be performed either through the abdominal or the vaginal wall. Verification of sperm deposition in the proximity of the ovaries improves fertility rates. Although associated with some risk of infection and an immune reaction against spermatozoa, the intraperitoneal technique rarely gives rise to severe anaphylactic shock, peritonitis, adhesion formation and the production of anti-sperm antibodies and these complications may be prevented by adequate sperm pretreatment and antibiotic therapy. The success of intraperitoneal insemination in humans, with results comparable with those of intrauterine insemination in the treatment of infertility, suggest the potential use of this technique in domestic mammals, especially in those in which intrauterine insemination poses practical difficulties. Some of the methods applied in human intraperitoneal insemination, such as confirming the position of the needle in the peritoneal cavity, and sperm pre-treatments might also improve results in domestic species. Conversely, the use of the animal model should help to develop some aspects of this technique in humans. [source] Tropaeolum tuberosum (Mashua) reduces testicular function: effect of different treatment timesANDROLOGIA, Issue 6 2008I. Cárdenas-Valencia Summary Tropaeolum tuberosum Ruiz & Pavon, along with other several species, is an edible-tuber crop that grows in the Andean region. Folk medicine describes the use of mashua to reduce reproductive function in men. The present study aimed to evaluate the effect of mashua (1 g kg,1) on sperm production in rats during 7, 12, 21 and 42 days of treatment. The following parameters were assessed: reproductive organ weights, spermatid count and daily sperm production (DSP), sperm count in epididymis and sperm transit and serum testosterone levels. Freeze-dried extract of mashua had 3.7 g 100 g,1 of benzyl glucosinolate. Mashua-treated rats showed a reduction in testicular spermatid number and DSP from day 12 to day 42; meanwhile, the effect of mashua was noted in epididymal sperm count after 12 and 42 days of treatment. In addition, epididymal sperm transit time was delayed at day 7 and it was accelerated on days 12 and 21 of treatment. No differences in serum testosterone levels were found between rats treated with vehicle and mashua after 42 days of treatment. Finally, mashua reduces testicular function after one spermatogenic cycle by reducing spermatid and sperm number, DSP and epididymal sperm transit time. [source] Male and female effects on fertilization success and offspring viability in the Peron's tree frog, Litoria peroniiAUSTRAL ECOLOGY, Issue 3 2008CRAIG D. H. SHERMAN Abstract There is increasing theoretical and empirical evidence that genetic compatibility among partners is an important determinant of fertilization success and offspring viability. In amphibians, females often actively choose partners from among a variety of males and polyandry is common. Genetic compatibility among partners may therefore be an important determinant of fertilization success and offspring viability in some amphibians. Amphibians also show some of the highest levels of genetic differentiation among neighbouring populations known in vertebrates, and as such, populations may have evolved different co-adapted gene complexes. This means that offspring from among-population crosses may have reduced fitness. It is therefore essential to understand to what extent crossings between and within populations may interfere with successful fertilization and offspring viability. Here, we test whether crossing individuals within and between two different populations of the Australian Peron's tree frog (Litoria peronii) using artificial fertilizations affect fertilization success and offspring viability. Fertilization success per se is strongly influenced by male identity, which is likely to depend at least to some extent on the experimental procedure (e.g. resulting in variation in sperm number per ejaculate), whereas there was no fertilization effect of female identity. More importantly, male and female identity, independently of each other, explained significant variation in offspring viability, whereas no such effect could be linked to population of origin. Thus, our experiments suggest that crossing populations may not always be the most significant factor affecting fertilization success or offspring viability, but may be more influenced by the genetic quality or the genetic compatibility of partners. [source] Effect of infusion volume and sperm numbers on persistence of uterine inflammation in maresEQUINE VETERINARY JOURNAL, Issue 2 2000E. Nikolakopoulos No abstract is available for this article. [source] Operational Sex Ratio and Alternative Reproductive Behaviours in Chinese Bushcricket, Gampsocleis gratiosaETHOLOGY, Issue 4 2006Yong Gao The effects of operational sex ratio (OSR) on male mating tactics in the Chinese bushcricket Gampsocleis gratiosa were investigated in male- and female-biased environments. We measured fresh and dry spermatophore contents and copulation duration, and counted sperm numbers of each copulation. The fresh weight of spermatophore and spermatophylax was positively correlated with male body weight. The males in a strongly male-biased environment produced significantly heavier fresh ampulla and more sperm per ejaculation, which were likely tactics for successful matings under the competition of rivals. The spermatophore might function as a structure to protect the fertilization potential of the ejaculate from rival males. [source] PLASTICITY IN REPRODUCTIVE PHENOTYPES REVEALS STATUS-SPECIFIC CORRELATIONS BETWEEN BEHAVIORAL, MORPHOLOGICAL, AND PHYSIOLOGICAL SEXUAL TRAITSEVOLUTION, Issue 5 2008Charlie K. Cornwallis Reproductive success is determined by a complex interplay between multiple sexual traits that promote mate acquisition and, following copulation, provide control over paternity. The intensity of sexual competition that individuals experience often fluctuates, and here we investigate how this influences the expression of reproductive traits and their relationships. We show in the fowl, Gallus gallus, that males of different social status, which experience different intensities of sexual competition, before and after copulation, have different reproductive phenotypes. Dominant males are more vigilant, feed less, and have larger sexual ornaments than subordinate males. Experimentally manipulating social status revealed that these differences were phenotypically plastic, indicating multiple sexual traits were dependent on the social environment. We integrated these data with previous published findings on changes in sperm numbers and velocity to show that relationships between traits were different for males when they were dominant and when they were subordinate. Furthermore, when males switched status a complex array of negative and positive correlations between the degree traits changed was observed. Our results suggest that variation in the intensity of sexual competition generates reversible plasticity in reproductive phenotypes and that relationships between sexual traits may be variable and influence the evolution of reproductive strategies. [source] Mice lacking cyclin-dependent kinase inhibitor p19Ink4d show strain-specific effects on male reproductionMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 8 2007Gregory M. Buchold Abstract p19Ink4d is a member of the INK4 family of cyclin-dependent kinase inhibitors, which are important negative regulators of the G1-phase cyclin-dependent kinases CDK4 and CDK6. On a mixed C57BL/6,×,129P2/OlaHsd background, mice deficient for p19Ink4d exhibited defects in male reproductive function including testicular atrophy, alteration in serum follicle stimulating hormone, qualitative increase in germ cell apoptosis, and delayed kinetics of meiotic prophase markers (Zindy et al., 2001. Mol Cell Biol 21:3244,3255; Zindy et al., 2000. Mol Cell Biol 20:372,378). In this study, a quantitative assessment of these aspects of reproductive capacity demonstrated relatively mild deficits in p19Ink4d,/, males compared to controls. These effects did not dramatically worsen in older males although some seminiferous tubule defects were observed. Following marker-assisted backcrossing into the C57BL/6 background, p19Ink4d,/, males did not display defects in testis weights, sperm numbers, serum FSH, germ cell apoptosis, or kinetics of selected meiotic prophase markers. These studies indicate that a reduction in Ink4 family function by the loss of p19Ink4d is sufficient to induce mild reproductive defects in male mice with a mixed genetic background, but not in the C57BL/6 genetic background. Mol. Reprod. Dev. 74: 1008,1020, 2007. © 2007 Wiley-Liss, Inc. [source] Expression of aquaporins in the efferent ductules, sperm counts, and sperm motility in estrogen receptor-, deficient mice fed lab chow versus caseinMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2006Ricardo Ruz Abstract Estrogens play an important role in the male reproductive tract, and this is especially so for the efferent ductules, where ,-estrogen receptors (ER,) have been localized. Mice deficient in ER, (,ERKO mice) are infertile, and the effect appears to be due in part to retention of water at the level of the efferent ductules. In the present study, we examined the consequences of ER, deletion on the distribution of certain aquaporins (AQPs), water protein channels, in the efferent ductules and on sperm numbers and motility. In addition, the effects of feeding mice a regular lab chow diet, which contains phytoestrogens, known to affect male reproductive tract functions, and a casein diet, which lacks phytoestrogens, were also assessed. Light microscope immunolocalizations of AQP-1 and AQP-9 revealed dramatic reduction and patchier staining in ,ERKO mice with distal areas of the efferent ductules being more affected than proximal areas. No other changes in immunolocalizations were noted as a consequence of diet. Computer-assisted sperm analyses demonstrated a 62% reduction in cauda epididymal sperm/ml in ,ERKO mice fed lab chow, whereas 87% fewer sperm/ml were observed in ,ERKO mice fed casein, suggesting an enhanced role for sperm production and concentration in a diet containing phytoestrogens. All sperm motility parameters were altered to some degree in ,ERKO mice fed lab chow. Alterations in sperm motility parameters were also detected, but were less dramatic in ,ERKO mice fed casein. These data suggest that the decrease in AQP expression in the efferent ductules of ,ERKO mice contributes in part to water retention in this tissue, eventually leading to backflow of water into the testis, with subsequent decreases in sperm concentration and motility. The data also suggest that phytoestrogens, which are present in regular lab chow, can influence the male reproductive tract with and without the presence of ER,, promoting efferent ductule and epididymal functions when ER, is expressed, but inhibiting these same functions when ER, is missing. Taken together the data underscore the importance of estrogens and ER, in maintaining sperm maturation and preventing male infertility. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc. [source] Effects of FSH receptor deletion on epididymal tubules and sperm morphology, numbers, and motilityMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2005Amit Grover Abstract Follicle stimulating hormone (FSH) interacts with its cognate receptor (R) on Sertoli cells within the testis and plays an important role in the maintenance of spermatogenesis. Male FSH-R knockout (FORKO) mice show fewer Sertoli cells and many that are structurally abnormal and as a consequence fewer germ cells. Lower levels of serum testosterone (T) and androgen binding protein (ABP) also occur, along with reduced fertility. To assess the effects of FSH-R depletion as an outcome of testicular abnormalities, sperm from the cauda epididymidis were counted and examined ultrastructurally. As reduced fertility may also reflect changes to the epididymis, the secondary responses of the epididymis to lower T and ABP levels were also examined by comparing differences in sizes of epididymal tubules in various regions of FORKO and wild type (WT) mice. Sperm motility was evaluated in FORKO mice and compared to that of WT mice by computer assisted sperm analysis (CASA). Quantitatively, the data revealed that epithelial areas of the caput and corpus epididymidis were significantly smaller in FORKO mice compared to WT mice. Cauda epididymal sperm counts in FORKO mice were also much lower than in WT mice. This resulted in changes to 9 out of 14 sperm motility parameters, related mostly to velocity measures, which were significantly lower in the FORKO mice. The greatest change was observed relative to the percent static sperm, which was elevated by 20% in FORKO mice compared to controls. EM analyses revealed major changes to the structure of the heads and tails of cauda luminal sperm in FORKO mice. Taken together these data suggest a key role for the FSH receptor in maintaining Sertoli cells to sustain normal sperm numbers and proper shapes of their heads and tails. In addition, the shrinkage in epididymal epithelial areas observed in FORKO mice likely reflect direct and/or indirect changes in the functions of these cells and their role in promoting sperm motility, which is noticeably altered in FORKO mice. Mol. Reprod. Dev. © 2005 Wiley-Liss, Inc. [source] Reproduction in male rats is vulnerable to treatment with the flavonoid-rich seed extracts of Vitex negundoPHYTOTHERAPY RESEARCH, Issue 1 2004Suwagmani Das Abstract A partially puri,ed ,avonoid-rich extract was prepared from the seed of Vitex negundo. The effect of this extract on the reproductive system of male rats was investigated at four different concentrations. All the major accessory sex organs shed weight when the preparation was administered at doses of ,15 mg/rat/day after 15 days of treatment. The drop in weight was also re,ected in disturbed tissue biochemistry. Secretory products such as citric acid in the prostate, fructose in seminal vesicles and epididymal , -glucosidase activity, indices of accessory sex organ function in males, diminished. Microscopic examination of the sperm derived from the cauda epididymides of treated animals showed only a marginal change in vitality. However, sperm numbers dwindled and slackness in their motility was observed, factors that may impede fertility. Toxicity testing in blood did not point to distress in any of the vital organs. Taken together, it is inferred that the seed extracts of V. negundo interfere with male reproductive function without producing adverse toxicity in other vital organs. Copyright © 2004 John Wiley & Sons, Ltd. [source] Assessing in vivo Fertilizing Capacity of Liquid-Preserved Boar Semen According to the ,Hanover Gilt Model'REPRODUCTION IN DOMESTIC ANIMALS, Issue 2 2003F Ardón Contents The goal of this study was to determine the ability of the Hanover gilt model to assess in vivo fertilizing capacity of preserved sperm and to consider whether any modifications to this model were needed. This model evaluates the fertilizing capacity of semen based on the fertilization rate, the rate of normal embryos and the accessory sperm count of 3,5-day embryos. Its distinguishing characteristics are the use of one-time insemination of sperm in reduced numbers, of spontaneously ovulating gilts and of ovulation detection through ultrasound examination of ovaries. Reduced sperm numbers allow for an accurate evaluation of the fertilizing potential of different semen treatments, thereby avoiding the compensatory effect of doses calibrated to maximize fertility. The model's usefulness was assessed in a trial run designed to compare the fertilizing capacity of liquid boar semen diluted into two different extenders. The diluent, the boar and the backflow, had no significant effect on any of the parameters studied. Gilts inseminated less than 24 h before ovulation had a significantly higher (p < 0.01) fertilization rate and accessory sperm cell count (p < 0.05) than those inseminated more than 24 h before ovulation. Very good/good embryos from homogeneous litters (only very good/good embryos were present) had a significantly higher (p < 0.01) accessory sperm count than those from heterogeneous litters (at least one embryo was of a different quality and/or oocytes were present). Both very good/good and degenerated/retarded embryos from heterogeneous litters had low accessory sperm numbers. This suggests that accessory sperm count is significantly related to the quality of the litter, but not to the quality of the embryo within gilts. It can be concluded that the Hanover gilt model is sensitive enough to show fertility differences (in this study, those associated with in vivo ageing of semen), while using relatively few gilts and little time. [source] | |||||||||||||