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PubMed1991

Reversible decreases of fertility in male Sprague-Dawley rats treated orally with finasteride, a 5 alpha-reductase inhibitor.

Finasteride, a 5 alpha-reductase inhibitor, was investigated for its effects on fertility in male rats as part of its preclinical safety assessment. Studies were initiated when the male Sprague-Dawley rats were either young (4 to 6 weeks old) or mature (15 weeks old). Treatment duration ranged from 6 to 32 weeks. Each male was cohabited with two untreated females at various periods during and after treatment. Litter parameters were evaluated on either day 14 or 20 of gestation. Males were necropsied at the end of treatment or 7 to 11 weeks following the end of treatment. The major findings of these studies were that 1) young rats given 20 to 80 mg/kg/day of finasteride first showed mild to moderate decreases in fertility after 12 weeks of treatment, whereas mature males (given only 80 mg/kg/day) did not show a similar decrease until 24 weeks of treatment, 2) fewer copulatory plugs and atrophy of prostates and seminal vesicles were associated with finasteride treatment, 3) the decreased fertility was only partial (ie, fertility index did not decrease below 48% of control in any study) and was not due to decreases in mating, 4) formation of copulatory plugs, organ weights, and fertility returned to normal levels after at least 6 weeks of drug withdrawal, and 5) the testes showed no histologic or weight changes that would explain the effect on fertility. These results show that the decreased fertility in male rats was associated with finasteride-induced inhibition of accessory gland secretions, an expected pharmacologic effect.

5-alpha Reductase Inhibitors↗
PubMed1992

Effects of oocyte exposure to local anesthetics on in vitro fertilization and embryo development in the mouse.

The effect on fertilization and development of local anesthetics routinely used during ultrasound-guided oocyte retrieval in women undergoing in vitro fertilization was examined in a mouse in vitro fertilization system. Mouse oocytes were exposed in vitro to lidocaine, chloroprocaine, and bupivacaine at concentrations of 0 (control), 0.01, 0.1, 1.0, 10.0, 100.0 micrograms/mL for 30 min, washed, and then inseminated. In vitro oocyte fertilization at 24 and 48 h and embryo development at 72 h were determined. Bupivacaine adversely affected mouse in vitro fertilization and embryo development only at the highest exposure concentration, 100 micrograms/mL, while lidocaine and chloroprocaine produced adverse effects at concentrations as low as 1.0 and 0.1 microgram/mL, respectively. Furthermore, an adverse dose-related effect on fertilization and embryo development was shown for lidocaine and chloroprocaine, but not for bupivacaine. These data demonstrate that the local anesthetics, lidocaine (L), chloroprocaine (C), and bupivacaine (B), adversely affect mouse in vitro fertilization and embryo development in the order of C greater than L greater than B.

Anesthetics, Local↗
PubMed1995

Prostaglandin synthesis by cumulus-oocyte complexes: effects on in vitro fertilization in mice.

Cumulus-oocyte complexes, obtained from superovulated Balb/C virgin female mice, released to the incubation media significant amounts of PGE1, PGE2 and PGF2 alpha, as estimated by bioassay. Fertilization rates in vitro decreased sharply when cumulus-oocyte complexes were treated with indomethacin (10(-6) M) and then inseminated with 5000 sperm per oocyte. In order to explore if the reduced prostaglandin (PG) concentration was responsible for diminished fertilization rates, PGE1, PGE2 and PGF2 alpha (10(-9) M) were added to the fertilization media of treated oocytes. PGE1 and PGE2 but not PGF2 alpha returned fertilization rates to control levels. Besides, PGE1 (10(-9) M) enhanced fertilization rates with reduced sperm numbers (1000 sperm per oocyte) of untreated cumulus-oocyte complexes. In conclusion, PG synthesis and release of mouse cumulus-oocyte complexes affects fertilization in vitro, and it is suggested that PGs of the E series modulate sperm function at the moment of fertilization.

Alprostadil↗
PubMed2004

Results of in vitro fertilization in patients with endometriomas: is surgical removal beneficial?

OBJECTIVE: The purpose of this study was to investigate the effect of endometriomas on clinical pregnancy rates of in vitro fertilization-embryo transfer. STUDY DESIGN: Infertile patients with endometriosis who underwent in vitro fertilization-embryo transfer were divided into group 1 patients who had a history of ovarian endometriomas and group 2 patients who did not. The patients in group 1 were further divided into group 1A who had their endometriomas removed by laparoscopic ovarian cystectomy before the start of in vitro fertilization-embryo transfer and group 1B who underwent in vitro fertilization-embryo transfer with the presence of endometriomas. The clinical pregnancy rates of these groups were compared. RESULTS: Clinical pregnancy rates per transfer were similar in group 1 and group 2 (40% vs 47%; P =.38) and similar in patients in group 1A and group 1B (47% vs 34%; P =.28), although the direction was toward improved pregnancy rates in the groups of patients without endometriomas present at the time of in vitro fertilization stimulation. When patients >39 years of age were excluded, the overall pregnancy rate was higher in those patients who had no current endometriomas than in those patients who had endometriomas present at the time of stimulation (65% vs 39%; P =.05). For patients with unilateral endometriomas, similar numbers of mature oocytes were aspirated between the affected and unaffected ovaries. CONCLUSION: Although the history of endometriomas does not appear to affect in vitro fertilization-embryo transfer outcomes adversely, there may be a benefit in the removal of endometriomas before in vitro fertilization.

Adult↗
PubMed2005

Advanced fertility diagnosis in stallion semen using transmission electron microscopy.

Routine semen analysis of stallions is based on light microscopy (LM). However, there are still a number of animals that are subfertile or even infertile not being identified with conventional semen analysis. The objective of this study was to investigate the suitability of transmission electron microscopy (TEM) for advanced fertility diagnosis in stallion. We examined ejaculates of 46 stallions with known fertility. Animals were divided into three different groups: group 1, fertile stallions (pregnant mares> or =70%, n=29); group 2, subfertile stallions (pregnant mares 10-69%, n=14); group 3, infertile stallions (pregnant mares<10%, n=3). Ejaculates were collected in spring 2002. Conventional semen analysis (volume, sperm concentration, motility, live:dead ratio and percentage of morphologically normal sperm) was immediately performed after semen collection. Ultrastructural analysis included the evaluation of 200 acrosomes, heads, midpieces and cross-sections of tails as well as 100 longitudinal sections of tails from every ejaculate. Using LM, we found a significant increase of morphological deviations from 24.5% (x ) in group 1 to 34.5% in group 2 and 73.5% in group 3. Using TEM, we found a significant increase of detached acrosomes from 6.1% in group 1 to 7.6% in group 2 and 21.4% in group 3. Deviations in tubule pattern were also increased (but not significant) from 2.7% in fertile and 2.8% in subfertile to 11.4% in infertile stallions as well as multiple tails from 1.9% in fertile to 2.0% in subfertile and 8.9% in infertile. Our data indicate that TEM is suitable for advanced fertility diagnostic in stallions, giving a connection between fertility and morphology. It suggests that the most likely reason for sub- and infertility in stallion in case of increased LM pathomorphology of semen are acrosomal alterations, especially detached acrosomes.

Acrosome↗
PubMed2005

Discrepancy between sperm acrosin activity and sperm morphology: significance for fertilization in vitro.

BACKGROUND: In routine semen analysis, discrepancies may occur between sperm acrosin activity test results and sperm acrosomal morphology. METHODS: Discrepant test results of sperm acrosin activity (spectrophotometric assay) vs. sperm morphology (strict criteria) in the initial diagnostic investigation of 107 infertile couples were evaluated with respect to fertilization rate (% oocytes with 2 pronuclei) further obtained in IVF treatment. RESULTS: Acrosin activity positively correlated with sperm morphology (% normal forms) (r=0.537) and fertilization rate (r=0.526). ROC curves for the prediction of > or =50% fertilization rate were comparable for acrosin activity and sperm morphology, with optimal cutoff values at 25 microIU/10(6) sperm and 10%, respectively. In multiple regression analysis, sperm acrosin activity (P=0.002) predicted fertilization rate independently of sperm morphology (P<0.001) and sperm vitality (eosin-nigrosin stain) (P=0.03). Acrosin activities > or =25 microIU/10(6) sperm were observed in 36% of severe teratozoospermic samples (< or =4% normal spermatozoa) associated with low fertilization rate. Twenty percent of the morphologically normal ejaculates showed a low acrosin activity (<25 microIU/10(6) sperm) and low hypoosmotic swelling test (HOST) scores (31.4+/-7.6%) and were associated with low fertilization rate. CONCLUSION: The sperm acrosin assay can help to predict sperm fertilizing capacity in IVF independently of sperm morphology.

Acrosin↗
PubMed2006

Mitochondrial content reflects oocyte variability and fertilization outcome.

OBJECTIVE: To determine the content of mitochondrial DNA (mtDNA) in oocytes from a range of patients with fertilization success and failure. DESIGN: Analysis of mtDNA content in fertilized and unfertilized oocytes and embryos by real-time polymerase chain reaction (PCR). SETTING: University hospital infertility and research center. PATIENT(S): Fifty-four women seeking treatment for infertility. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): A total of 142 fertilized and unfertilized oocytes were classified into three main groups. Group I consisted of 35 fertilized oocytes from 21 patients; group II, 65 unfertilized oocytes from 36 patients; and group III, 42 degenerate oocytes from 23 patients. Mitochondrial DNA content was determined by SYBR Green real-time PCR-based assay. RESULT(S): The mean mtDNA copy number for the fertilized oocytes was 250,454, whereas for the unfertilized group it was 163,698. There were significant differences for mtDNA copy number between the male factor and female factor infertility unfertilized oocytes and between the unexplained infertility and female factor infertility groups. The mean copy number for the degenerate oocyte group was 44,629, which was significantly different from the other subdivisions in this group. CONCLUSION(S): Mitochondrial DNA content is critical to fertilization outcome and serves as an important marker of oocyte quality, explaining some cases of fertilization failure.

Adult↗
PubMed2006

Fertilization and pregnancy outcome after intracytoplasmic injection with fresh or cryopreserved ejaculated spermatozoa.

OBJECTIVE: To assess fertilization, implantation, and pregnancy rates in patients undergoing ICSI using fresh and cryopreserved sperm from ejaculated semen samples. DESIGN: Retrospective study. SETTING: Academic and private medical centers. PATIENT(S): One hundred fifty-eight patients. INTERVENTION(S): Intracytoplasmic sperm injection. MAIN OUTCOME MEASURE(S): Fertilization, implantation, and pregnancy rates were evaluated; 61 cycles of ICSI were performed with cryopreserved and 79 cycles of ICSI were performed with fresh spermatozoa. Also, we divided the outcomes according to the semen characteristics, normozoospermia, oligozoospermia, asthenozoospermia, and oligoasthenozoospermia. RESULT(S): Overall, normal-fertilization rates were higher using fresh sperm (73.8%) compared with cryopreserved sperm (68.7%). Cycles performed in patients with normozoospermia or oligozoospermia had similar fertilization, implantation, and pregnancy rates using fresh or cryopreserved sperm. When asthenozoospermic and oligoasthenozoospermic semen samples were used, the normal-fertilization rate was higher with fresh sperm compared with cryopreserved sperm. However, implantation and pregnancy rates were similar in fresh and cryopreserved sperm samples from patients with asthenozoospermia or oligoasthenozoospermia. CONCLUSION(S): Semen with abnormalities in the motility may be more susceptible to sperm cryopreservation damage, resulting in lower fertilization rates. However, once the oocyte is fertilized, implantation and pregnancy rates are similar to those in patients with oligozoospermia and normozoospermia.

Adult↗
PubMed2004

A general solution for optimal egg size during external fertilization, extended scope for intermediate optimal egg size and the introduction of Don Ottavio 'tango'.

Egg sizes of marine invertebrates vary greatly, both within and between species. Among the proposed causes of this are a trade-off between egg size, egg number and survival probability of offspring, and a selection pressure exerted by sperm limitation during external fertilization. Although larger eggs are indeed a larger target for sperm, producing larger eggs also implies making fewer of them. There has been discussion about whether sperm limitation can (theoretically) and does (in nature) select for larger egg size than under ad libitum sperm. In one specific model, based on a particular fertilization kinetics model and an empirically derived mortality function, the theoretical possibility of a negative shift in optimal egg size with sperm concentration was demonstrated. Here we present a generalized analytical model to explore the effects of survival and fertilization probabilities on optimal egg size. It is demonstrated that incorporating fertilization kinetics greatly increases the scope for intermediate optimal egg size, as opposed to eggs of minimal or maximal size. Second, we present a general analytical qualitative solution to the question whether optimal egg size depends on sperm concentration. It is shown that, under the condition that an intermediate optimal egg size exists, this qualitative outcome of the model (positive, negative or no relation between optimal egg size and sperm limitation) depends on the structure of the fertilization kinetics part of the model. Finally, we evaluate fertilization kinetics models with respect to the general solution, using two previously published kinetics models ('Don Giovanni' and 'Don Ottavio') and a novel alteration of one of them in which sperm concentration covaries with egg concentration (Don Ottavio 'tango'). For all three models the relationship between optimal egg size and sperm concentration is shown to be always negative. This paper thus shows how biologically realistic relationships between egg size on the one hand and survival and fertilization probability on the other hand predict optimal egg size to be intermediate, and that this optimum is in general expected to increase when sperm become more limiting.

Animals↗
PubMed2005

Low temperature storage of rhesus monkey spermatozoa and fertility evaluation by intracytoplasmic injection.

The objective was to develop a sperm freezing procedure suitable for use in the propagation of valuable founder animals by assisted reproductive technologies. Here, we report a comparison of processing methods by measuring the motility of fresh and frozen-thawed rhesus monkey spermatozoa and fertility via intracytoplasmic spermatozoa injection (ICSI) of sibling oocytes. Washed spermatozoa were frozen in straws or in pellets using different cryoprotective media and processed post-thaw with or without a density gradient centrifugation step. Among the four study series, motility post-thaw was improved with density gradient centrifugation (17-24% versus 75%, P<0.01) achieving levels similar to fresh spermatozoa. Spermatozoa injected oocytes (total n=377) were co-cultured on BRL cells and observed for fertilization and development. With spermatozoa frozen in straws in liquid nitrogen vapors, the fertilization rate after ICSI was lower than with fresh spermatozoa (40-44% versus 77-86%, P<0.05), even with the Percoll-enriched fraction that exhibited robust motility. In contrast, somewhat slower freezing of spermatozoa in pellets on dry ice supported fertilization rates (73%) that were similar to the fresh counterpart. Developmental rates of fertilized eggs were similar in all experiments. A total of 106 embryo transfers has resulted in the first primate born after ICSI with F/T ejaculated spermatozoa plus 22 other infants to date. Additionally, a 3-4 h incubation after thawing improved the fertilization rate with spermatozoa from a male with poor post-thaw recovery of sperm motility. In conclusion, an acceptable fertilization rate after ICSI with motile, frozen-thawed primate spermatozoa was observed comparable to that obtained with fresh spermatozoa allowing small quantities of competent spermatozoa to be used with ICSI to facilitate propagation of desirable primate genotypes.

Animals↗
PubMed2004

Birth of mice after in vitro fertilization using C57BL/6 sperm transported within epididymides at refrigerated temperatures.

The transportation of cryopreserved spermatozoa is an economical, efficient, and safe method for the distribution of mouse strains from one facility to another. However, spermatozoa from some strains, including C57BL/6 (B6), are very sensitive to freezing and thawing and frequently fail to fertilize eggs by conventional in vitro fertilization methods at the recipient mouse facility. Since many genetically engineered mice have the B6 genetic background, this sensitivity poses a major obstacle to studies of mouse genetics. We investigated the feasibility of transporting spermatozoa within epididymides under non-freezing conditions. First, we examined the interval that B6 and B6D2F1 (BDF1) spermatozoa retained their ability to fertilize when stored within epididymides at low temperatures (5 degrees C or 7 degrees C). Fertilization rates were >50%, irrespective of the spermatozoa used, when epididymides were stored for 3d at 7 degrees C. B6 spermatozoa, but not BDF1 sperm, had better retention of fertilizing ability at 7 degrees C versus 5 degrees C. We then transported freshly collected B6 and BDF1 epididymides from a sender colony to a recipient colony using a common package delivery service, during which the temperature was maintained at 5 degrees C or 7 degrees C for 2d. Sufficiently high fertilization rates (68.0-77.5%) were obtained for all experimental groups, except for B6 spermatozoa transported at 5 degrees C. These spermatozoa were successfully cryopreserved at the recipient facility and, yielded post-thaw fertilization rates of 27.6-66.4%. When embryos derived from the B6 spermatozoa that were transported at 7 degrees C were transferred into recipient females, 52.7% (38/72) developed to term. In conclusion, transportation of epididymides at refrigerated temperatures is a practical method for the exchange of mouse genetic resources between facilities, especially when these facilities do not specialize in sperm cryopreservation. For the B6 mouse strain, the transportation of epididymides at 7 degrees C rather than 5 degrees C, is recommended.

Animals↗
PubMed2005

Comparison of in vitro laboratory analyses with the fertility of cryopreserved stallion spermatozoa.

Assessing the fertilizing potential of a semen sample is important for effective stallion management and for rapid progress in evaluating new cryopreservation technologies. Unfortunately, sperm motility does not estimate fertility well. These experiments established assays to measure cell viability, acrosomal integrity and mitochondrial function for cryopreserved stallion spermatozoa, using flow cytometry, and determined the variability associated with these assays. Correlations between results for these laboratory assays and stallion fertility were also determined. The inter-assay variability for visual motility, computer assisted motility, and sperm velocity, sperm viability, percent viable-acrosome intact cells and mitochondrial function of cells were all similar, however, intra-assay variability was lower for flow cytometric assays than for motility assays. The reliability of all assays were >0.72, except for sperm velocity (0.32). Although visual motility and the straightness of sperm motility conducted 90 min after thawing were correlated with seasonal fertility (0.56 and 0.55, respectively), data from no single assay were correlated with first-cycle fertility rates (P > 0.05). Best models using data from multiple assays explained 66 to 73, 76 to 89 and 79 to 94% of the variability in fertilizing potential, when two, three and four variables were included, respectively. Caution is required in interpreting these data, as only a few stallions were evaluated and relatively few mares were bred to each stallion, however, they do indicate that using a few rapid and inexpensive sperm assays, we can begin to understand factors important in stallion sperm fertilizing capacity, and we can use these assays to more effectively evaluate new methods for cryopreserving stallion spermatozoa.

Acrosome↗
PubMed2005

Uroplakin III, a novel Src substrate in Xenopus egg rafts, is a target for sperm protease essential for fertilization.

In a previous study, we identified Xenopus egg uroplakin III (xUPIII), a single-transmembrane protein that localized to lipid/membrane rafts and was tyrosine-phosphorylated upon fertilization. An antibody against the xUPIII extracellular domain abolishes fertilization, suggesting that xUPIII acts not only as tyrosine kinase substrate but also as a receptor for sperm. Previously, it has been shown that the protease cathepsin B can promote a transient Ca2+ release and egg activation as seen in fertilized eggs (Mizote, A., Okamoto, S., Iwao, Y., 1999. Activation of Xenopus eggs by proteases: possible involvement of a sperm protease in fertilization. Dev. Biol. 208, 79-92). Here, we show that activation of Xenopus eggs by cathepsin B is accompanied by tyrosine phosphorylation of egg-raft-associated Src, phospholipase Cgamma, and xUPIII. Cathepsin B also promotes a partial digestion of xUPIII both in vitro and in vivo. A synthetic xUPIII-GRR peptide, which contains a potential proteolytic site, inhibits the cathepsin-B-mediated proteolysis and tyrosine phosphorylation of xUPIII and egg activation. Importantly, this peptide also inhibits sperm-induced tyrosine phosphorylation of xUPIII and egg activation. Protease activity that digests xUPIII in an xUPIII-GRR peptide-sensitive manner is present in Xenopus sperm. Several protease inhibitors, which have been identified to be inhibitory toward Xenopus fertilization, are shown to inhibit sperm-induced tyrosine phosphorylation of xUPIII. Uroplakin Ib, a tetraspanin UP member, is found to be associated with xUPIII in egg rafts. Our results highlight novel mechanisms of fertilization signaling by which xUPIII serves as a potential target for sperm protease essential for fertilization.

Animals↗
PubMed1997

Coculture of human embryos with buffalo rat liver cells for women with decreased prognosis in in vitro fertilization.

OBJECTIVE: The coculture of human embryos with epithelial cells may improve both embryo quality and pregnancy rates. In this current study we tested the efficacy of coculture with the buffalo rat liver cell line on pregnancy rates in women with a potentially poor prognosis for success with in vitro fertilization (previous in vitro fertilization failure, advanced maternal age, increased early follicular follicle-stimulating hormone levels, and anovulation). STUDY DESIGN: This prospective controlled study evaluated a total of 203 women (135 coculture, 68 controls) undergoing in vitro fertilization. Implantation rates per embryo, clinical pregnancy rates, and continuing/delivered pregnancy rates were analyzed. RESULTS: Buffalo rat liver cells, which are commercially available, are stable in coculture. Implantation rates (number of sacs with fetal heart motion per embryos transferred) were similar for coculture (19%) and control (18%) embryos. No difference in the rate of continuing/delivered pregnancies per retrieval was noted (17% coculture vs 14% control) in the group with advanced maternal age, but coculture caused a trend toward improved pregnancy rates in the group with ovulatory dysfunction (43% coculture vs 14% control) and the group with previous in vitro fertilization failure (34% coculture vs 28% control). CONCLUSION: This is the first published controlled study to our knowledge that reports the use of the buffalo rat liver cell coculture for human in vitro fertilization in a large number of patients. Our data support consideration of buffalo rat liver coculture for in vitro fertilization for women with previous in vitro fertilization failure and possibly for patients with oocyte or ovulatory dysfunction.

Adult↗
PubMed1984

The influence of seminal characteristics on the success rate of human in vitro fertilization.

The relationship of conventional semen parameters and the limits of these parameters for fertilization in vitro were analyzed from data over a 3-year period (1980 to 1982). Sperm motility was the single most important parameter determining the fertilization rate. Fertilization failed when the initial and final motilities were less than 20% and 30%, respectively. The percentage of abnormal sperm forms was also significantly related to the fertilization rate; but even when there were greater than 60% abnormal spermatozoa, fertilization could be obtained. Sperm concentration in semen had no significant effect on the fertilization rate when the data were controlled for motility or abnormal sperm forms. The fertilization rate increased with reduced sperm numbers used for insemination in vitro but had no effect on the incidence of multiple pronuclei in oocytes.

Fertilization in Vitro↗
PubMed1985

Removal of the cumulus oophorus from the human oocyte for in vitro fertilization.

Removal of cumulus may increase the chance of fertilization in patients with sperm antibodies, may facilitate fertilization in vitro with a small number of spermatozoa, and is necessary for microsurgical injection procedures in vitro. The aim of this study was to establish whether removal of the cumulus has any detrimental effects on the fertilization rate and embryo viability. Removal of cumulus cells from the human oocyte with bovine testicular hyaluronidase did not interfere with fertilization, early embryonic development, or pregnancy. This suggests that human spermatozoa can spontaneously undergo capacitation and fertilize oocytes in vitro in a chemically defined medium containing 10% preovulatory human serum. In three patients with low-quality semen, removal of the cumulus and the addition of hypotaurine and epinephrine apparently did not improve the motility nor the fertilizing capacity of the spermatozoa. Delayed fertilization and cleavage arrest was observed in one patient when spermatozoa obtained from the body region of the epididymis was used for insemination.

Culture Media↗
PubMed1985

Effect of the number of inseminating sperm and the follicular stimulation protocol on in vitro fertilization of human oocytes in male factor and non-male factor couples.

The effect of sperm concentration and follicular stimulation protocol on in vitro fertilization of human oocytes is not well established. Comparison was made of three inseminating concentrations (250,000, 375,000, and 500,000 progressively motile sperm/oocyte) and three protocols (human menopausal gonadotropin [hMG], clomiphene citrate [CC], and combination hMG/CC) on the fertilization rate of mature and immature oocytes in couples with male factor and non-male factor infertility. In non-male factor couples, total fertilization rates for CC, hMG, and hMG/CC were 70.3%, 54.5%, and 68.8%, respectively, while total fertilization rates at the varying number of inseminating sperm were not significantly different. Mature oocytes were more likely than immature oocytes to fertilize. Among semen male factor couples, there was no difference in fertilization by stimulation protocol; however, insemination with the higher number of inseminating sperm resulted in an increased fertilization rate.

Clomiphene↗
PubMed1992

The relationship between sperm ultrastructural features and fertilizing capacity in vitro.

OBJECTIVE: To evaluate the relationship between ultramorphological features of the human sperm and its fertilizing capacity in vitro. DESIGN: The study was performed retrospectively. Ultrastructural features were assessed using scanning and transmission electron microscopes in sperm samples of individuals who underwent an in vitro fertilization (IVF) treatment cycle no more than 6 months before the study. SETTING: Institutional clinical care. PATIENTS: Fifty-six infertile couples in whom mechanical infertility was diagnosed in the female partner. Patients were categorized as fertilizing when fertilization of at least 30% of the oocytes occurred (n = 27) and nonfertilizing when none of the oocytes fertilized in at least two consecutive IVF treatment cycles (n = 29). RESULTS: The two groups differed significantly only in ultramorphological parameters of the sperm head and acrosome (head, F(8,36) = 2.8, P less than 0.02; acrosome, F(4,40) = 2.8, P less than 0.04), and especially in the following malformation patterns: hyperelongated head, acrosome deficiency, and acrosome damage. The suggested score based on these findings was able to predict 90% and 76% of the cases with and without fertilizing potential, respectively. CONCLUSION: The ultrastructural morphology of the sperm head components is a key parameter for assessing the sperm fertilizing capacity in vitro.

Adult↗