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PubMed2002

Comparison of the Sperm Quality Analyzer IIC variables with the computer-aided sperm analysis estimates.

Sperm Quality Analyzer (SQA) IIC, an upgrade version, is an inexpensive device and provides a quantitative estimation of sperm motility, whereas the use of computer-aided sperm analysis (CASA) provides high precision and provision of quantitative data on sperm kinetics. The aim of the present study was to evaluate if the SQA IIC variables correlated with the CASA estimates. Semen quality analysis of 71 fresh semen samples was performed using SQA IIC and CASA. Total sperm concentration, percentage of progressively motile sperm, percentage of normal morphology, motile sperm concentration, sperm motility index (SMI) and functional sperm count (FSC) determinations were performed using SQA IIC. Sperm concentration, sperm motility, and sperm motion variables including amplitude of lateral head displacement (ALH), beat cross frequency (BCF), curvilinear velocity (VCL), straight line velocity (VSL), average path velocity (VAP), linearity (LIN=VSL/VCL), and straightness (STR=VSL/VAP) were evaluated simultaneously on the same semen samples using CASA. The sperm characteristics were compared between SQA IIC and CASA. There were significant correlations of sperm concentration (r=0.634, p < 0.0001), sperm motility (r=0.697, p < 0.0001), and motile sperm concentration (r=0.757, p < 0.0001) between the two devices. Both SMI and FSC significantly correlated with eight CASA estimates, including sperm concentration, sperm motility, motile sperm concentration, ALH, VCL, VSL, VAP, and Rapid. SQA IIC is simple and easy to use. Moreover, the SQA IIC variables well correlated with the CASA estimates. As a screening test for semen quality, SQA IIC is considered as useful in the management of male infertility.

Diagnosis, Computer-Assisted↗

PubMed2001

Subcellular localization of beta1,4-galactosyltransferase on bull sperm and its function during sperm-egg interactions.

The process of sperm-oocyte recognition is a complex interaction between the plasma membrane of sperm and the extracellular matrix of the oocyte. The best studied mammalian system is the mouse, in which sperm plasma membrane receptors recognize specific oligosaccharides on the egg coat glycoprotein ZP3. A well-defined ZP3 receptor on mouse sperm is beta1,4-galactosyltransferase (GalT). In this study, we investigated the possibility that GalT is present on bull sperm, and that it may participate during bovine sperm-oocyte binding. Using Western immunoblotting, bull sperm were found to have a protein of molecular weight similar to mouse GalT at approximately 60 kDa. Immunogold low voltage scanning electron microscopy reveals that GalT epitopes are confined to the anterior cap of fresh or capacitated bull sperm. To investigate the function of bovine sperm GalT, fresh bull sperm were pretreated with either preimmune or anti-GalT antibody and added to in vitro-matured bovine oocytes. Sperm exposed to preimmune serum fertilized 82.7% (153 of 185) of the oocytes, whereas sperm exposed to anti-GalT antiserum fertilized only 42.3% (202 of 478) of the oocytes. We determined whether the inhibition of fertilization resulted from a direct inhibition of sperm-oocyte binding. The number of sperm bound to eggs was determined by low voltage scanning electron microscopy following pretreatment with preimmune or anti-GalT antibody. An average of 25.3+/-2.2 (mean +/- SEM) sperm bound per half-oocyte when treated with preimmune serum. In contrast, exposure of sperm to anti-GalT antiserum significantly lowered (P<0.001) the frequency of sperm binding to 9.9+/-0.8 bound per half-oocyte. These results show that GalT is present on the anterior cap of the bovine sperm head, where it participates in fertilization by facilitating sperm-oocyte binding. The function of GalT in both the murine and bovine systems suggests that it may serve as a generalized gamete receptor in mammals.

Animals↗

PubMed2004

Effects of heparin and sperm concentration on cleavage and blastocyst development rates of bovine oocytes inseminated with flow cytometrically-sorted sperm.

The objective was to determine the optimal concentration of heparin for sperm capacitation, as well as the optimal sperm concentration for in vitro fertilization using flow cytometrically-sorted sperm from individual bulls. A total of 5327 bovine oocytes and sperm from four bulls were examined. Oocytes from slaughterhouse ovaries were matured in TCM199 for 22-24 h. Flow cytometrically-sorted sperm as well as unsorted control sperm from the same bulls were cryopreserved. For sperm from each of the four bulls, oocytes were inseminated in a three-by-three factorial design plus one control group (three heparin concentrations: 0, 2, and 10 microg/ml and three sperm concentrations: 0.5 x 10(6), 1.5 x 10(6), and 4.5 x 10(6) ml(-1); 10 microg/ml of heparin and 1.5 x 10(6) ml(-1) of sperm were used for the unsorted control). Presumptive zygotes were cultured in chemically defined media, CDM-1 and CDM-2 for 52-54 h and 96 h, respectively. Samples of about 10 oocytes from each of the 10 treatment groups per replicate were fixed at 18-20 h after insemination to determine sperm pronuclei formation and polyspermy. Increased polyspermy resulted as heparin and sperm concentrations increased (P < 0.05). A higher rate of polyspermy was found in oocytes inseminated with unsorted control sperm compared with sorted sperm (P < 0.05). Sperm of one of four bulls tested required no heparin and lower concentration (0.5 x 10(6) ml(-1)) to obtain optimal cleavage and blastocyst rates while optimal parameters for another bull were higher heparin (10 microg/ml) and sperm concentrations (4.5 x 10(6) ml(-1)). Optimal parameters for the other two were intermediate levels of heparin and sperm. Sperm appeared to be partially capacitated during the flow cytometric-sorting process used for sex pre-determination. When heparin and sperm concentrations were optimized for individual bulls, blastocyst production per oocyte was similar for sorted and unsorted sperm for three of the four bulls studied.

Animals↗

PubMed2001

[The associations between concentration of selenium in semen and sperm parameters as well as oxidative DNA damage in human sperm].

OBJECTIVE: To explore the associations between concentrations of selenium (Se) in serum and semen and sperm parameters as well as oxidative DNA damage in human sperm. METHODS: Concentrations of selenium in serum and semen were determined using atomic absorption spectrophotometer (AAS). The sperm parameters were detected according to WHO laboratory manual for the examination of human sperm. The levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and deoxyguanosine (dG) in human sperm DNA were measured using HPLC-ECD and HPLC-UV. RESULTS: Mean semen concentration of selenium was significantly higher in fertile subjects (0.74 mumol/L) than that in infertile subjects (0.56 mumol/L), while there was no significant difference in serum concentrations of selenium between the two groups. Semen volume (3.91 ml vs. 2.79 ml), sperm density (46.4 x 10(9)/L vs. 36.5 x 10(9)/L) and sperm count (168.0 x 10(6) vs. 102.0 x 10(6)) were significantly higher in fertile subjects than those in infertile subjects. There was no significant difference in motility and viability of sperm, and proportion of deformity sperm between the two groups, Significantly positive correlation was observed between semen concentration of Se and sperm density (r = 0.48, P < 0.01 for fertile subjects and r = 0.32, P < 0.05 for infertile subjects) as well as sperm count (r = 0.32, P < 0.05 for fertile subjects and r = 0.26, P < 0.05 for infertile subjects), sperm motility (r = 0.46, P < 0.01 for fertile subjects and r = 0.65, P < 0.01 for infertile subjects) and viability (r = 0.33, P < 0.05 for fertile subjects and r = 0.64, P < 0.01 for infertile subjects). There was no correlation between serum Se concentrations and sperm parameters. Moreover, 8-OHdG levels in sperm DNA inversely correlated with semen Se concentrations in fertile (r = -0.21, P < 0.05) and infertile (r = -0.28, P < 0.05) subjects. However, no significant correlation was found between 8-OHdG levels in sperm DNA and serum Se concentrations in all subjects. CONCLUSIONS: Semen concentrations of Se were associated with sperm quality and 8-OHdG levels in human sperm. Serum concentrations of Se did not affect sperm quality and oxidative DNA damage in human sperm.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2002

Morphometric characterization and classification of alpaca sperm heads using the sperm-class analyzer computer-assisted system.

Sperm morphology has been identified as one characteristic which can be useful in the prediction of sperm fertility, therefore, we hope that this study aimed at establishing standardized morphological criteria might serve in future studies dealing with the search for sperm parameters which facilitate an estimation of sperm quality. For this purpose, ejaculates from fertile alpacas were used to evaluate sperm head morphometry by means of the Sperm-Class Analyzer (SCA) computer-aided image analysis system. We defined three morphological categories according to sperm head size (normal 50%, small 26%, large 24%) and five categories according to sperm head shape (normal 47%, pyriform 3%, short 20%, round 1%, long 29%). Sperm classification according to shape was performed by first morphometrically characterizing sperm heads clearly falling into each of the shape categories. Thereafter, discriminant analysis was performed on the data from these typical sperm heads and the resulting classification functions were used to categorize 2,200 spermatozoa from 11 alpacas. Classification of sperm heads by this method agreed in 88% of the cases with most of the misclassifications being due to pyriform heads classified as long heads. Morphometric values obtained from samples of 50, 100, 150, 175 and 200 sperm heads were compared. At least 150 sperm heads should be evaluated to overcome sample size influence on sperm measurements. Significant differences in sperm morphometry were found between individuals (CV for morphometric parameters ranging from 1.3 to 13.0) and there were marked differences in the sperm morphological composition of the ejaculates. Within-animal CV ranged from 4.7 to 17.8 thus showing the high degree of sperm polymorphism present in the alpaca ejaculate.

Animals↗

PubMed2003

Sperm mobility phenotype not determined by sperm quality index.

We tested the capacity of the AviMate sperm quality analyzer to predict sperm mobility phenotype. A preliminary experiment was performed to determine a sperm concentration that afforded maximal sperm quality index (SQI) values with sperm from males with high sperm mobility. In order to facilitate comparison of sperm motility indexes, semen was diluted to aconstant concentration of 1.25 million sperm/mL rather than a constant ratio of 1:75 as recommended for the sperm quality analyzer. Thereafter, sperm mobility, motile concentration, and SQI were measured from a single ejaculate collected from each of 70 broiler breeders. Coefficients of variation were 60, 37, and 30%, respectively. Neither sperm mobility (r = 0.01) nor motile concentration (r = 0.14) was highly correlated with SQI. Neither motile concentration nor straight line velocity (VSL) differed (P > or = 0.05) among roosters whose SQI values were below or above one standard deviation from the population mean (n = 10 per group). In contrast, both motile concentration (P < or = 0.01) and VSL (P < or = 0.05) differed between roosters whose sperm mobility values were below or above a standard deviation from the population mean (n = 10 per group). Sperm mobility was a function of the size of a highly motile subpopulation of sperm. A replicate experiment was performed with a flock of New Hampshire roosters (n = 126). Neither the properties of motile sperm nor fertility differed among males characterized by extreme SQI scores. We concluded that variation in SQI scores was enigmatic because sperm concentration was controlled in our experiments, sperm viability was invariant, and motile concentration did not differ among roosters characterized by extreme SQI scores. In summary, the AviMate sperm quality analyzer did not predict sperm mobility phenotype.

Animals↗

PubMed1995

Sperm immobilizing antibodies interfere with sperm migration from the uterine cavity through the fallopian tubes.

PROBLEM: It is well known that sperm migration in cervical mucus is impaired by sperm immobilizing antibodies secreted in the mucus. However, it is not clear yet whether sperm migration from the uterine cavity through the fallopian tubes to the peritoneal cavity is impaired by sperm immobilizing antibodies. To test the possible impairment of sperm migration in the tubes, laparoscopic examinations were carried out and the presence of motile sperm in the peritoneal fluid after intra-uterine insemination was investigated. METHOD: Peritoneal sperm recovery tests were performed in 28 infertile women with sperm immobilizing antibodies in their sera, and the results were compared with those in 322 infertile women without the antibodies. Both the sperm immobilizing antibody titers (SI50) and complement activities (C'H50) in peritoneal fluid were compared with those in patients' sera. In some experiments, the supernatant of the peritoneal fluid was used as a source of complement for the sperm immobilization tests instead of guinea pig serum. RESULTS: Among couples with normal semen characteristics by the criteria of WHO, sperm recovery in the peritoneal fluid was observed in only 3 (11.1%) of 27 patients with sperm immobilizing antibodies, compared with 72 (34.0%) of 212 patients without the antibodies (P < 0.025). The antibody titers of the patients with the sperm recovery were very low by the quantitative sperm immobilization test. In most patients, a similar amount of sperm immobilizing antibodies was present in the peritoneal fluid and the sera. Though the complement activities in the peritoneal fluid were less than those in sera, the former were still found to be sufficient to immobilize sperm in vivo. CONCLUSIONS: These results suggest that the complement-dependent sperm immobilizing antibodies could interfere with sperm migration in the female genital tract at the level of the fallopian tubes.

Animals↗

PubMed1996

Relationship between the zona pellucida (ZP) and ionophore A23187-induced acrosome reaction and the ability of sperm to penetrate the ZP in men with normal sperm-ZP binding.

OBJECTIVE: To determine whether the proportions of sperm undergoing the acrosome reaction (AR) on the zona pellucida (ZP) or on exposure to the calcium ionophore A23187 correlate with sperm-ZP penetration in men with normal sperm-ZP binding. DESIGN: Sperm samples from 14 fertile, 50 normozoospermic, and 21 teratozoospermic men with normal sperm-ZP binding were used to study ZP and ionophore-induced AR and sperm-ZP penetration. SETTING: University research unit associated with a clinical infertility and IVF program. MAIN OUTCOME MEASURES: The proportion of sperm undergoing the AR induced by ZP and A23187, the number of sperm bound to and penetrating into the ZP, the proportion of ZP penetrated by sperm, and semen characteristics were analyzed. RESULTS: There were highly significant correlations between the percentage AR of sperm bound to the ZP and both the proportion of ZP penetrated and average number of sperm penetrating per ZP (Spearman r = 0.697 and 0.703). In contrast, A23187-induced AR did not correlate with either ZP-induced AR or sperm-ZP penetration. Although sperm concentration in semen correlated with both ZP-induced AR and sperm-ZP penetration by Spearman test, it was not significant in multivariate regression analyses. CONCLUSION: Ionophore A23187-induced AR does not correlate with either ZP-induced AR or sperm-ZP penetration. The ZP-induced AR is correlated highly with sperm-ZP penetration. Testing ZP-induced AR may be useful for assessing infertile men with normal sperm-ZP binding. In particular, it will identify failure of ZP penetration because of specific defects of the AR on the ZP.

Acrosome↗

PubMed1990

Hyaluronic acid (Sperm Select) improves retention of sperm motility and velocity in normospermic and oligospermic specimens.

The effects of Sperm Select (Pharmacia AB, Uppsala, Sweden), a hyaluronic acid medium, on the motility and membrane integrity properties of sperm were studied. In 15 normospermic specimens after overnight incubation, the motility parameters in the control versus the Sperm Select group were as follows (mean +/- SEM): motility, 18.8% +/- 2.8% versus 27.4% +/- 2.9%; velocity, 21.5 +/- 2.4 versus 27.2 +/- 2.2 microns/s; linearity, 3.8 +/- 0.3 versus 4.4 +/- 0.2; lateral head displacement, 1.5 +/- 0.2 versus 1.9 +/- 0.1 microns; and tail beat/cross frequency, 8.8 +/- 1.3 versus 10.8 +/- 1.4 Hz. The density of motile sperm was 10.8 +/- 2.3 versus 18.5 +/- 2.5 X 10(6) sperm/mL. Finally, the velocity coefficient, the multiple of the sperm motility and linear velocity, was 4.6 +/- 1.1 versus 8.1 +/- 1.4. However, we found no Sperm Select related differences when testing sperm membrane integrity with hypoosmotic swelling and supravital staining. Thus, Sperm Select improves the retention of sperm motility (most prominently velocity) apparently due to a direct action of hyaluronic acid on sperm metabolism or contractility rather than to preservation of sperm membrane integrity. In 20 oligospermic specimens, Sperm Select caused similar improvements in sperm motility, and the duration of motility could be predicted from the degree of enhancement in sperm velocity after short-term Sperm Select exposure. A modified Sperm Select protocol is described that further increases motile sperm yield without a centrifugation step.

Bisbenzimidazole↗

PubMed1994

Sib competition and sperm competitiveness: an answer to 'why so many sperms?' and the recombination/sperm number correlation.

Sperm, or inter-ejaculate, competition leads to the evolution of many sperm per ejaculate. However, sperm competition theory does not predict the correlation between sperm number and chiasma, or that between sperm number and haploid chromosome number. Firstly, we show that phylogenetic inertia cannot account for at least the latter relation, and secondly, a model is presented which incorporates sib competition (intra-ejaculate competition) and sperm competitiveness to explain the relation between sperm numbers and recombination and the question 'Why so many sperms?'. It is argued that if there are deleterious mutations which affect sperm competitiveness this will lead to sib or intra-ejaculate competition. If inter-ejaculate competition also exists, then there will be selection for increased recombination. A chiasmate male heterozygous for n mutations which reduce sperm competitiveness can produce gametes with 0...n mutations. The proportion of gametes with 0 mutations per ejaculate is s = 0.5n, which is a small fraction. This means that to ensure on average one sperm with 0 mutations per ejaculate, a chiasmate male must produce 1/s sperm. We may therefore expect that 1/s will be positively correlated with sperm numbers. If inter-ejaculate competition leads to an optimum sperm number of x, then the optimum number of sperm per ejaculate is x/s. Sperm numbers will be increased by: (i) the number of loci which affect sperm competitiveness in the haploid state; (ii) the mutation rate; and (iii) the recombination rate. A correlation between recombination rates and sperm numbers is therefore to be expected.

Animals↗

PubMed1992

Effects of antibodies to sperm surface fertilization antigen-1 on human sperm-zona pellucida interaction.

OBJECTIVE: To investigate the effects of antibodies to well-defined sperm surface antigens (the fertilization antigen [FA-1] and germ-cell antigen [GA-1]) and nuclear antigen (protamine) on human sperm-zona interaction. DESIGN: Number of total and acrosome-reacted human sperm bound to the human zona pellucida and the sperm movement characteristics assessed by computer-aided sperm analysis were evaluated after incubation of sperm with the antibodies. SETTING: Academic research environment approved by the Institute Review Board. PATIENTS: Human oocytes were obtained from ovaries removed at surgery. Semen from fertile donors was used in all assays. INTERVENTIONS: Human oocytes were stored in salt solution at -80 degrees C until used. Spermatozoa were treated with the antibodies to various sperm antigens. MAIN OUTCOME MEASURES: Total and acrosome-reacted sperm bound to zona pellucida and sperm movement characteristics were evaluated after 3 to 5 hours of incubation of the antibodies with human sperm. RESULTS: Anti-FA-1 antibodies significantly reduced human sperm fusion with zona-free hamster oocytes and sperm binding to the human zona pellucida but did not affect binding of acrosome-reacted sperm and sperm movement characteristics. Anti-GA-1 and antiprotamine antibodies did not affect sperm-oocyte interaction, acrosomal reaction, or sperm motility. CONCLUSIONS: Antibodies to FA-1 but not to GA-1 and protamine inhibit human sperm-zona interaction.

Acrosome↗

PubMed1998

The risk of sperm competition and the evolution of sperm heteromorphism.

Members of the Drosophila obscura species group exhibit sperm heteromorphism in which males simultaneously produce two different morphologies of sperm, short and long. Short sperm represent at least 50% of the ejaculate in several species but do not function in fertilization and thus, the evolutionary significance of this phenomenon is unknown. Selective pressures associated with the risk of sperm competition have been suggested to explain the maintenance of sperm heteromorphism. Here I test: (1) whether males alter their behaviour or ejaculate characteristics in response to the risk of sperm competition, and (2) whether short, nonfertilizing sperm serve as 'cheap filler' in the female reproductive tract, thereby delaying female receptivity to subsequent matings. Males did not alter tactics based on the risk of sperm competition; copulation durations of males mated to nonvirgin females were unexpectedly shorter than when both sexes were virgin and, contrary to sperm competition predictions, males did not alter the ratio of fertilizing:nonfertilizing sperm relative to female mating status or female age. Short sperm had a small, if any, role in influencing female remating behaviour. The number and proportion of short sperm present in sperm storage organs did not differ between nonvirgin receptive and nonvirgin nonreceptive females. The proportion of short sperm present in the ventral receptacle, however, was lower in receptive than nonreceptive females. Remating behaviour was strongly linked to oviposition patterns. Nonvirgin receptive females oviposited more eggs than nonreceptive females, and female remating interval was positively related to both the number of eggs and progeny produced. Although, oviposition parameters are related to fertilization and thus, the use of long sperm, nonvirgin receptive and nonreceptive females did not predictably differ in the number or proportion of long sperm in storage. These results suggest oviposition per se is probably more important than sperm in determining female receptivity and that sperm heteromorphism may play a marginal, if any, role in affecting female remating. (c) 1998 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1982

A role for mouse sperm surface galactosyltransferase in sperm binding to the egg zona pellucida.

Past studies have suggested that mouse sperm surface galactosyltransferase may participate during fertilization by binding N-acetylglucosamine (GlcNAc) residues in the zona pellucida. In this paper, we examined further the role of sperm surface galactosyltransferase in mouse fertilization. Two reagents that specifically perturb sperm surface galactosyltransferase activity both inhibit sperm-zona binding. The presence of the milk protein alpha-lactalbumin specifically modifies the substrate specificity of sperm galactosyltransferase away from GlcNAc and towards glucose and simultaneously inhibits sperm binding to the zona pellucida. Similarly, UDP-dialdehyde inhibits sperm binding to the zona pellucida and sperm surface galactosyl-transferase activity to identical degrees. Of five other sperm enzymes assayed, four are unaffected by UDP-dialdehyde, and one is affected only slightly. Covalent linkage of UDP-dialdehyde to sperm dramatically inhibits binding to eggs, while treatment of eggs with UDP-dialdehyde has no effect on sperm binding. Heat-solubilized or pronase-digested zona pellucida inhibit sperm-zona binding, and they can be glycosylated by sperm with UDP-galactose. Sperm are also able to glycosylate intact zona pellucida with UDP-galactose. Thus, solubilized and intact zona pellucida act as substrates for sperm surface GlcNAc:galactosyltransferases. Finally, pretreatment of eggs with beta-N-acetylglucosaminidase inhibits sperm binding by up to 86%, while under identical conditions, pretreatment with beta-galactosidase increases sperm binding by 55%. These studies, in conjunction with those of the preceding paper dealing with surface galactosyltransferase changes during capacitation, directly suggest that galactosyltransferase is at least one of the components necessary for sperm binding to the zona pellucida.

Acetylglucosaminidase↗

PubMed1998

Sperm pellet analysis: a technique to detect the presence of sperm in men considered to have azoospermia by routine semen analysis.

PURPOSE: In men considered to have azoospermia by routine semen analyses sperm may be identified after centrifuging the semen. Because these sperm may be used for intracytoplasmic sperm injection, we describe our technique and findings of sperm pelleting. MATERIALS AND METHODS: Semen centrifugation for sperm pellet analysis was performed in 140 consecutive men in whom no sperm was identified on routine semen analysis and who were categorized as having obstructive or nonobstructive azoospermia. Obstructive azoospermia was defined as failed vasectomy reversal, failed reconstruction for congenital vasal or epididymal occlusion, or an acquired obstruction unrelated to ejaculatory duct obstruction. Patients with congenital absence of the vas deferens or who had undergone vasectomy were not included in the study. Nonobstructive azoospermia was defined as moderate to severe testicular atrophy with markedly elevated serum follicle-stimulating hormone (greater than 3 times normal), or a testicular biopsy that revealed maturational arrest, severe hypospermatogenesis or the Sertoli-cell-only pattern. Obstructive and nonobstructive azoospermia were present in 70 men who provided 109 samples and 70 who provided 103, respectively. RESULTS: Motile and nonmotile sperm was identified in 13 of the 70 patients (18.6%) with obstructive and in 16 of the 70 (22.8%) with nonobstructive azoospermia. Pellet variability, that is the absence of sperm in 1 specimen and its presence in another from the same patient, was noted in 7 of the 17 men (41.2%) with obstructive and 2 of the 17 (11.8%) with nonobstructive azoospermia (not statistically significant). Motile sperm was present in the pellets of 6 of the 70 men (8.6%) with obstructive and 15 of the 70 (21.4%) with nonobstructive azoospermia. The median number of motile sperm was lower in the obstructive than in the nonobstructive group (0 sperm in 17 samples versus 5 sperm in 41 samples, p <0.001). The median value of 0 in the obstructive azoospermia group reflects the finding that 9 of the 17 samples did not contain motile sperm. Similarly the median number of nonmotile sperm was lower in the obstructive than in the nonobstructive group (5 versus 8 sperm). CONCLUSIONS: We demonstrated the presence of motile and nonmotile sperm in a significant number of men considered to have azoospermia by routine semen analysis. Semen centrifugation (sperm pelleting) should be performed in all men considered to have this condition by routine semen analysis, especially those with testicular failure and those in whom intracytoplasmic sperm injection is possible.

Centrifugation↗

PubMed2001

Sperm competition experiments between lines of crickets producing different sperm lengths.

Sperm numbers can be important determinants of fertilization success in sperm competition. However, the importance of variation in sperm size is less well understood. Sperm size varies significantly both between and within species and comparative studies have suggested that some of this variance can be explained by sperm competition. In this study we examine whether variation in sperm length has consequences for fertilization precedence using controlled sperm competition experiments in the field cricket Gryllus bimaculatus. This species is an ideal model for such investigations because the mechanism of sperm competition generates complete mixing of different males' spermatozoa in the female (thereby allowing individual sperm to express their own competitive abilities). We successfully bred lines of crickets, the males of which produced short, medium and long sperm types with narrow and non-overlapping distributions. Males of different lines were then sequentially mated with control females in order to create two-male sperm competitions. The paternity outcomes of these competitions were measured after matings using an irradiated male technique (with a full reciprocal design that controls for natural fertility and any irradiation effects on gamete competitiveness) over a 12 day oviposition period. However, having successfully bred diverging sperm length lines and competing males that differed in sperm length, we found no evidence that a male's sperm size explained any of the variation in their relative fertilization success. Males from lines producing longer sperm showed no fertilization advantage over males producing shorter sperm across 97 double matings. There was also no advantage for males producing a sperm length close to the population mean over those competitors whose sperm length had been selectively diverged across 63 matings.

Animals↗

PubMed1976

Sperm concentration dependency in the fertilization and zonae sperm binding properties of mouse eggs inseminated in vitro.

Sperm penetration of zonae and fertilization of mouse eggs in vitro was studied as a function of sperm concentration over the range 10(3)-10(6) cells/ml. Maximal fertilization was obtained at 10(5) sperm/ml with markedly reduced levels seen at lower concentrations. Eggs inseminated at low sperm concentrations were, however, characterized by the absence of multiple sperm penetrations of their zonae and by the retention of an intact cumulus oophorus during culture. Penetration levels were similar in eggs inseminated with and without an intact cumulus, although increases in supernumerary and supplemental sperm were observed with partly denuded ova. The distribution of sperm found within eggs inseminated in vitro was compared with a distribution predicted by chance alone. The similarity in observed and expected distributions indicated that a functional zona reaction was absent in eggs inseminated in vitro. Sperm binding to zonae of cumulus-free unfertilized mouse eggs was shown to be related to sperm concentration over the range 10(3)-10(6) cells/ml. Zonae sperm binding sites, while too numerous for accurate quantitation, exceeded 100 per zona. The interrelationships between sperm penetration of and sperm binding to the zonae of cumulus-free eggs were examined. At low sperm concentrations, the ratio of sperm/zonae with bound sperm to sperm/penetrated egg approached one, although the total number of bound sperm exceeded the total number of penetrating sperm. That proportion of cells in a preincubated epididymal sperm suspension, capable of binding to the zona was determined and employed in an estimation of the extent of sperm capacitation.

Animals↗

PubMed1989

Sperm from tw32/+ mice: capacitation is normal, but hyperactivation is premature and nonhyperactivated sperm are slow.

The t complex in the mouse is a large group of linked genes that affect sperm function in fertilization. In t/+ males, sperm carrying the t complex (t sperm) have normal fertilizing ability, while sperm carrying the normal homolog (+t sperm) are dysfunctional (P. Olds-Clarke and B. Peitz, 1985, Genet. Res. 47, 49). The specific step in fertilization which is dysfunctional, however, is not known. Two characteristics of fertilizing sperm, capacitation (the process by which sperm become capable of undergoing the acrosome reaction) and hyperactivation (the change in swimming behavior concomitant with capacitation), were assayed by objective methods in epididymal sperm from tw32/+ males of two strains, and compared to sperm from +/+ males of the same strains. Capacitated and acrosome-reacted sperm were identified by a chlortetracycline assay (C.R. Ward and B.T. Storey, 1984, Dev. Biol. 104, 287). Hyperactivated sperm were identified by their path shape and swimming speed, using a computer-assisted motion-analysis system (J.M. Neill and P. Olds-Clarke, 1987, Gamete Res. 18, 121). Hyperactivation occurred significantly sooner among sperm from tw32/+ mice than among sperm from +/+ mice of the same strain, while the rates and maximal levels of capacitation and spontaneous acrosome reactions were normal. Of the nonhyperactivated motile sperm from tw32/+ mice, almost all were slower than sperm from +/+ mice of the same strain. While the effect of premature hyperactivation on fertilization is not clear, slow movements are likely to impair fertilizing ability. These results raise the possibility that the slow sperm are the dysfunctional +t sperm.

Acrosome↗

PubMed2001

Equine sperm-oocyte interaction: the role of sperm surface hyaluronidase.

The plasma membrane over the sperm head of several mammalian species has been shown to express a glycerolphosphatidylinositol-linked hyaluronidase known as PH-20. This protein has been associated with the sperm's interaction with the oocyte cumulus matrix and zona pellucida. The characteristics of PH-20 in equine sperm have not been clearly defined. In this study, ejaculated gel-free semen from five stallions and epididymal sperm from isolated epididymis from 10 stallions was used to characterize the PH-20 activity in equine sperm. Affinity purified anti-equine PH-20 polyclonal antibody was used to immunodetect sperm surface-associated PH-20 and immunolabel whole sperm. The intracellular calcium indicator, Fluo-3, was used to assess sperm intracellular calcium. Stallion sperm express a surface-associated hyaluronidase localized to the posterior sperm head region in ejaculated sperm. Following in vitro capacitation and acrosomal exocytosis, the inner acrosomal membrane (IAM) displays intense hyaluronidase fluorescence suggesting that the IAM and hyaluronidase plays a significant role in zona penetration by sperm. Sperm incubated in hyaluronan (HA)-containing capacitation medium display an elevated intracellular calcium concentration (P<0.01) that is associated with translocation of PH-20 antigenic sites on the sperm surface in addition to increases in protein tyrosine phosphorylation. Caput- and cauda-derived sperm display developmentally unique PH-20 immunofluorescence expression patterns. These data suggest that the differential expression of PH-20 in ejaculated and epididymal sperm could be involved in cumulus penetration, sperm-egg recognition, and oolemmal fusion in this species.

Acrosome Reaction↗