The relationship between sperm ultrastructural features and fertilizing capacity in vitro

Holographic imaging of unlabelled sperm cells for semen analysis: a review

Male reproductive health in both humans and animals is an important research field in biological study. In order to characterize the morphology, the motility and the concentration of the sperm cells, which are the most important parameters to feature them, digital holography demonstrated to be an attractive technique. Indeed, it is a label-free, non-invasive and high-resolution method that enables the characterization of live specimen. The review is intended both for summarizing the state-of-art on the semen analysis and recent achievement obtained by means of digital holography and for exploring new possible applications of digital holography in this field. Quantitative phase maps of living swimming spermatozoa.

Sperm nuclear vacuoles in relation to acrosome reactions and sperm motility

We investigated sperm nuclear vacuolation in relation to acrosome reactions and the maintenance of sperm motility. Thirty male patients who visited our Male Infertility Clinic were enrolled. These patients underwent conventional semen analyses, Acrobeads tests, and high-magnification observation of the sperm head to evaluate the degree of nuclear vacuolation on the Acrobeads test scoring after 24 hours of incubation. The presence of acrosome reactions was evaluated using the Acrobeads test. The spermatozoa were classified into three groups: (I) those bound to MH61-beads, (II) motile spermatozoa that did not bind to MH61-beads, and (III) immotile spermatozoa that did not bind to MH61-beads. The percentage of spermatozoa with large nuclear vacuoles (%LNV) was compared between the three groups. The degree of sperm nuclear vacuolation was evaluated in 17,992 ejaculated spermatozoa. The mean %LNVs were 2.4% in group I, 5.8% in group II, and 9.8% in group III. These values were significantly different from each other (P < 0.001, paired t-test). There were no correlations between the %LNV values and the Acrobeads scores. In conclusion, the degree of sperm nuclear vacuolation was significantly lower in the acrosome-reacted spermatozoa and spermatozoa with maintained motility, and higher in the immotile spermatozoa that did not bind to MH61-beads.

Observation of spermatozoa by a high-magnification microscope

Semen analyses are the primary tool for evaluating male infertility, as semen parameters are useful for predicting potential fertility. In the field of assisted reproductive technology (ART), the single best motile spermatozoon should be selected, especially when performing intracytoplasmic sperm injection (ICSI). In this context, the motile sperm organelle morphology examination (MSOME) was developed as a method of assessing the detailed morphology of motile spermatozoa in real time at a magnification of up to 6,300× on a video system. The use of ICSI with MSOME-selected sperm is called intracytoplasmic morphologically selected sperm injection (IMSI). IMSI improves the outcomes of ICSI. MSOME can be also applied to evaluate male infertility. Among MSOME parameters, the presence of sperm nuclear vacuoles is the most important finding. Large sperm nuclear vacuoles (LNV) are related not only to poor ART outcomes, but also to poor semen quality and sperm DNA damage, such as DNA fragmentation and chromatin condensation failure. It has been suggested that sperm head vacuoles are produced at earlier stages of sperm maturation. It is possible that the number of LNV can be decreased by surgical or medical treatment for male infertility. Therefore, the level of LNV has the potential to be used as an alternative parameter of semen quality and a new tool for evaluating the therapeutic effects of treatment in male patients with infertility.

Quality of human spermatozoa: relationship between high-magnification sperm morphology and DNA integrity

The aim of this work is to establish the relationship between the morphology of Intracytoplasmic Morphologically Selected Sperm Injection (IMSI)-selected spermatozoa and their DNA integrity. The 45 ejaculates were randomly distributed into three treatment groups: normozoospermic, oligoasthenozoospermic and oligoasthenotheratozoospermic samples. The evaluation of DNA integrity was performed using the sperm chromatin dispersion test. It was established that DNA integrity of spermatozoa is strongly dependent on ejaculate quality (P < 0.05). The count of spermatozoa with nonfragmented DNA in normozoospermic samples was high and independent from IMSI-morphological classes (Class 1 versus Class 3, respectively) (P > 0.1). With decreased ejaculate quality, the percentage of spermatozoa with nonfragmented DNA decreased significantly (P < 0.05) independent from morphological class. Nevertheless, the rate of IMSI-selected spermatozoa with fragmented DNA within of Class 1 in normozoospermic (Group 1), in oligoasthenozoospermic (Group 2) and in oligoasthenotheratozoospermic (Group 3) samples was 21.1%, 31.8% and 54.1%, respectively. In conclusion, there is a direct relationship between morphological parameters of spermatozoa and their DNA integrity. However, the IMSI technique alone is not enough for the selection of spermatozoa with intact nuclei.

Digital holographic microscopy for the evaluation of human sperm structure

The morphology of the sperm head has often been correlated with the outcome of in vitro fertilization, and has been shown to be the sole parameter in semen of value in predicting the success of intracytoplasmic sperm injection and intracytoplasmic morphologically selected sperm injection. In this paper, we have studied whether digital holographic microscopy (DHM) may be useful to obtain quantitative data on human sperm head structure and compared this technique with high-power digitally enhanced Nomarski optics. The main advantage of digital holography is that high-resolution three-dimensional quantitative sample imaging may be automatically produced by numerical refocusing of a two-dimensional image at different object planes without any mechanical scanning. We show that DHM generates useful information on the dimensions and structure of human sperm, not revealed by conventional phase-contrast microscopy, in particular the volume of vacuoles, and suggest its use as an additional prognostic tool in assisted reproduction technology.

Les larges vacuoles des têtes spermatiques sont-elles associées à des altérations du noyau ou de l’acrosome du spermatozoïde ?

Objectifs

Rechercher la présence d’altérations nucléaires ou acrosomiques dans les spermatozoïdes présentant des vacuoles occupant au moins 13 % de la surface de la tête des spermatozoïdes (spermatozoïdes dits de type 3), détectées à l’aide de la technique MSOME (motile sperm organelle morphology examination).

Matériel et méthodes

Notre étude a été effectuée sur des recueils de sperme de 20 hommes infertiles. Une évaluation de l’acrosome par immunomarquage à l’aide d’un anticorps monoclonal antiproacrosine (Mab4D4) a été associée à une détection de la fragmentation de l’ADN par la technique TUNEL. La condensation de la chromatine spermatique a été évaluée par une coloration au bleu d’aniline, et le taux d’aneuploïdie a été déterminé par hybridation in situ en fluorescence (FISH). Une observation des échantillons spermatiques par microscopie électronique à transmission (MET) [sperme entier] et confocale [spermatozoïdes de type 3 isolés] a complété ces analyses. Les résultats ont été comparés entre des spermatozoïdes provenant du sperme entier et des spermatozoïdes de type 3 isolés.

Résultats

Une augmentation significative de la proportion d’acrosomes anormaux a été constatée dans les spermatozoïdes isolés de type 3 par comparaison au sperme entier (77,8 ± 2,49 % vs 70,6 ± 2,62 %). La fragmentation de l’ADN a été observée de manière comparable dans les spermatozoïdes de type 3 et le sperme entier (14,5 ± 3,45 % vs 11,5 ± 1,25%), un défaut de condensation de la chromatine ainsi qu’une augmentation significative du taux d’aneuploïdie ont été retrouvés dans les spermatozoïdes isolés par comparaison à ceux provenant du sperme entier (50,4 ± 3,10 % vs 26,5 ± 2,60 % et 7,8 ± 1,98 % vs 1,3 ± 0,18 %). Les larges vacuoles sont à localisation nucléaire exclusive (MET et microscopie confocale).

Conclusion

Les vacuoles seraient en relation directe avec un défaut de maturation nucléaire survenant au cours de la spermiogenèse.

Correlation of post swim-up acrosome index with in-vitro fertilization outcomes

PURPOSE

A prospective study was planned to determine the relationship between post swim-up acrosome index (AI) evaluation and fertilization outcomes in an in vitro fertilization (IVF) program.

MATERIALS AND METHODS

Infertile couples who have applied to IVF were admitted into this study when the male partner's sperm concentration was > 20 x 10(6)/mL and motility > 30%. Pre- and post swim-up semen quality parameters including concentration, motility, sperm morphology and AI were evaluated in a prospective, randomized and blinded fashion. The couples were divided prospectively into 2 groups. In group I (25 couples) 50 000 sperm per oocyte were used for insemination considering post swim-up acrosome index, and in group II (25 couples) 50 000 sperm per oocyte were used for insemination without considering post swim-up acrosome index.

RESULTS

Pre- and post swim-up AI were 30.8 +/- 3.4 and 17.8 +/- 4.5 in group I, and 31.4 +/- 3.6 and 16.3 +/- 4.7 in group II (p > 0.05) respectively. The significant improvement in morphology and motility after double wash swim-up procedure has been observed. However, double wash swim-up procedure could not eliminate head and especially acrosomal defects which would directly effect fertilization capacity in conventional IVF program. In group I, 85.3% of oocytes were fertilized, with a 48% pregnancy rate; in group II, 71.0% of oocytes were fertilized, with a pregnancy rate of 20%. Fertilization and pregnancy rates were significantly different (p < 0.05) between the two groups.

CONCLUSION

We have concluded that it could be useful to consider post swim-up AI of sperm inseminated in conventional IVF cycles, which correlates with high fertilization and pregnancy rates.

Impaired fertility and spermiogenetic disorders with loss of cell adhesion in male mice expressing an interfering Rap1 mutant

The guanosine trisphosphatase Rap1 serves as a critical player in signal transduction, somatic cell proliferation and differentiation, and cell-cell adhesion by acting through distinct mechanisms. During mouse spermiogenesis, Rap1 is activated and forms a signaling complex with its effector, the serine-threonine kinase B-Raf. To investigate the functional role of Rap1 in male germ cell differentiation, we generated transgenic mice expressing an inactive Rap1 mutant selectively in differentiating spermatids. This expression resulted in a derailment of spermiogenesis due to an anomalous release of immature round spermatids from the seminiferous epithelium within the tubule lumen and in low sperm counts. These spermiogenetic disorders correlated with impaired fertility, with the transgenic males being severely subfertile. Because mutant testis exhibited perturbations in ectoplasmic specializations (ESs), a Sertoli-germ cell-specific adherens junction, we searched for expression of vascular endothelial cadherin (VE-cadherin), an adhesion molecule regulated by Rap1, in spermatogenic cells of wild-type and mutant mice. We found that germ cells express VE-cadherin with a timing strictly related to apical ES formation and function; immature, VE-cadherin-positive spermatids were, however, prematurely released in the transgenic testis. In conclusion, interfering with Rap1 function during spermiogenesis leads to reduced fertility by impairment of germ-Sertoli cell contacts; our transgenic mouse provides an in vivo model to study the regulation of ES dynamics.

How to improve IVF–ICSI outcome by sperm selection

In previous studies, a new IVF method of intracytoplasmic morphologically selected sperm injection (IMSI) was introduced, based on motile sperm organellar morphology examination (MSOME). It was concluded that microinjection of morphologically selected sperm cells with strictly normal nucleus, defined by MSOME, improves IVF-ICSI outcome. The aim of the present study was to confirm this conclusion in new, enlarged study groups. Comparison between 80 couples, who underwent an IVF-IMSI trial, with matched couples, who underwent a standard IVF-ICSI procedure, confirmed that pregnancy rate following IVF-IMSI was significantly higher, and abortion rate significantly lower than in the routine IVF-ICSI (60.0 versus 25.0%, and 14 versus 40% respectively, P <or= 0.05). Another comparison was performed between matched IMSI groups, where embryos were obtained from microinjection by spermatozoa with a morphologically normal nucleus ('best' group, n = 70) and a 'second best' group was selected, where embryos were obtained from microinjection of spermatozoa with minimal morphological impairment, since no other sperm cells were available. It was confirmed that microinjection by 'second best ' spermatozoa result in significantly lower pregnancy and delivery rates and significantly higher abortion rates than microinjection with 'best' spermatozoa (25.7 versus 58.2%, P <or= 0.01; 17.1 versus 52.8%, P <or= 0.01, and 33.3 versus 9.7%, P <or= 0.02 respectively). The present study has strengthened previous conclusions.

The morphological normalcy of the sperm nucleus and pregnancy rate of intracytoplasmic injection with morphologically selected sperm

BACKGROUND

Our preceding studies have already demonstrated the advantage of intracytoplasmic morphologically selected sperm injection (IMSI) over the conventional IVF-ICSI procedure in terms of pregnancy rate. This study was undertaken to determine whether the increased pregnancy outcome was attributable to the preferred nuclear morphology of the selected spermatozoa, and not to the special sperm preparation technique modified by IMSI.

METHODS

Comparison between two matched IMSI groups, i.e. negative comprising 38 cycles, where no spermatozoa with intact nuclei were available for microinjection; and positive, involving ovum microinjection by spermatozoa with strictly defined morphologically normal nuclei.

RESULTS

Implantation and pregnancy rates were significantly higher, and abortion rates significantly lower, in the positive group compared with the negative group (25.0+/-25.9 versus 5.9+/-12.9%, F=15.8, P< or =0.01; 52.6 versus 18.4%, chi2=9.7, P< or =0.01; and 10.0 versus 57.1%, chi2=7.1, P< or =0.02, respectively).

CONCLUSIONS

Implantation and pregnancy by ICSI is associated with morphological nuclear normalcy of sperm. Sperm with a morphologically abnormal nucleus usually have low fertility potential, but some with certain nuclear abnormalities may still be able to produce pregnancy following ICSI.

Real-time fine morphology of motile human sperm cells is associated with IVF-ICSI outcome

The aim of the present prospective study was to determine whether subtle sperm morphological characteristics affect the outcome of intracytoplasmic sperm injection (ICSI), and if so, to identify those that are relevant. For this purpose, we developed a new method, the motile sperm organelle morphology examination (MSOME). The examination is performed in real time using an inverted light microscope equipped with high-power Nomarski optics enhanced by digital imaging to achieve a magnification up to 6300x. MSOME was applied to the leftover sperm fraction selected for microinjection in 100 random couples referred for ICSI treatment at 3 major in vitro fertilization centers. We found that the morphological normalcy of the entire sperm cell, according to MSOME criteria, was positively associated with ICSI fertilization rate (area under the receiver operating characteristics [ROC] curve, 88%) but not with pregnancy outcome. The morphological normalcy of the sperm nucleus, defined by MSOME, was significantly and positively associated with both fertilization rate and pregnancy outcome (areas under the ROC curve, 72% and 74%, respectively). These findings indicate that ICSI-associated pregnancy rate may be affected by subtle morphological malformations of the sperm nucleus, which may remain undetected by the embryologist during the routine selection procedure.

Effects of long-term treatment with human pure follicle-stimulating hormone on semen parameters and sperm-cell ultrastructure in idiopathic oligoteratoasthenozoospermia

Ten subfertile men affected by idiopathic oligoteratoasthenozoospermia and exhibiting normal serum hormone levels received a long-term treatment with human pure follicle-stimulating hormone (hp-FSH) (150 IU, intramuscularly, three times per week for 6 months). Semen parameters and ultrastructural features of spermatozoa were evaluated before and after therapy. The results showed an increase in sperm cell concentration and, more interestingly, motility. Electron microscopic examination revealed an improved fine architectural pattern, mainly involving acrosome, head and chromatin and middle-piece, in accordance with the positive changes of functional data. No significant changes of hp-FSH treatment on serum hormone levels were observed, since the latter were found to be substantially unchanged after 6 months of therapy. The present data suggest: (i) the benefit of hp-FSH administration in idiopathic oligoteratoasthenozoospermia, when hormone parameters support a substantial integrity of spermatogenetic microenvironment and (ii) an optimal effect after long-term (6 months) therapy.

Assessment of the dominant abnormal form is useful for predicting the outcome of intracytoplasmic sperm injection in the case of severe teratozoospermia

PURPOSE

Our purpose was to investigate the relation between the dominant sperm anomaly and sperm morphology and the outcome of intracytoplasmic sperm injection (ICSI).

METHODS

Two hundred ninety-five patients who underwent a total of 181 cycles of in vitro fertilization (n = 168) and/or 217 cycles of ICSI (n = 177) between July 1995 and May 1997 at Keio University Hospital were investigated.

RESULTS

The rates of fertilization and pregnancy were 63.3 and 27.8%, respectively, in ICSI cycles with < or = 4% normal forms. When the percentage of strictly normal morphology was < or = 4, the fertilization rate was lower in the case of severely tapered head (13.0%; n = 4) than in the cases of other deformities in ICSI. The acrosomal defect made no difference in the fertilization rate with ICSI.

CONCLUSIONS

The predominant abnormal form affects the ICSI outcome in the case of < or = 4% normal forms.

Quantitative ultramorphological analysis of human sperm: fifteen years of experience in the diagnosis and management of male factor infertility

The advantages of quantitative ultramorphological (QUM) sperm analysis in the diagnosis and treatment of male infertility are presented. The QUM methodology is based on three elements: complementary scanning electron microscopy and transmission electron microscopy observations of 7 sperm cell subcellular organelles (acrosome, postacrosomal lamina, nucleus, neck, axoneme, mitochondrial sheath, and outer dense fibers); systematic classification of the specific ultramorphological malformations into 4 pathological and the normal categories, indicating the morphological state of each subcellular organelle; and comparison between well-defined reference groups with opposite fertility status or treatment conditions. QUM has established 2 indices for the in vivo and in vitro male fertility potential: (1) Natural Fertility Index (NFI), with accurate prediction (97% sensitivity and 90% specificity) of 80% of the male patients; and (2) IVF score, with prediction of 76% of the nonfertilizing and 90% of fertilizing IVF groups. QUM has enabled assessment of ultramorphological indications for varicocele and radiation exposure. Varicocele causes defects in sperm head organelles related to early spermatid development, whereas ionizing radiation causes amorphous head shape. QUM established criteria for specific non-in-vitro therapeutic interventions, including varicocelectomy, follicle-stimulating hormone (FSH) administration, and acupuncture. The varicocele index enabled correct classification of 79 and 89% of patients with and without varicocele. Males with idiopathic impairment of sperm acrosome and nucleus are potential responders to FSH treatment, whereas patients exhibiting low sperm activity are candidates for acupuncture treatment. Patients with a low Natural Fertility Index are recommended for an assisted reproduction technique (ART). based on the ultramorphology of the tail axoneme. Patients who achieved pregnancy following intrauterine insemination or in vitro fertilization and those whose wives conceived only following intracytoplasmic sperm injection were classified with accuracy of 78 and 74%, respectively. QUM sperm analysis is clinically informative, nontraumatic, and cost-effective, and is recommended when the male infertility factor cannot be clearly diagnosed by routine tests prior to first ART trial.

Quantitative ultramorphological (QUM) analysis of human sperm: diagnosis and management of male infertility

The advantages of quantitative ultramorphological (QUM) sperm analysis in the diagnosis and treatment of male infertility are presented. QUM methodology is based on three elements: (1) complementary SEM and TEM observations of 7 sperm cell subcellular organelles: acrosome, postacrosomal lamina, nucleus, neck, axoneme, mitochondrial sheath, and outer dense fibers; (2) systematic classification of the specific ultramorphological malformations into 4 pathological and the normal categories, which indicate the morphological state of each subcellular organelle; and (3) comparison between well-defined reference groups with opposite fertility status or treatment conditions. QUM analysis has enabled the establishment of two indices that optimally express the in vivo and in vitro male fertility potential: The Natural Fertility Index (NFI), which allowed an accurate prediction (97% sensitivity and 90% specificity) of 80% of the naturally fertile and suspected infertile male patients, and the in vitro fertilization (IVF) score, which enabled prediction of 76% of the nonfertilizing and 90% of the fertilizing IVF groups. Validation tests confirmed these data. QUM also enabled assessment of ultramorphological indications for varicocele and radiation exposure: Both male factor etiologies indicated a persistent effect on the natural fertility potential, as expressed by structural changes in the nucleus. Varicocele was found to cause defects in the sperm head organelles related to early spermatid development, whereas ionizing radiation resulted in amorphous head shape. Criteria for specific non-in vitro therapeutic interventions such as varicocelectomy, follicle-stimulating hormone (FSH) administration, and acupuncture treatment were established. A varicocele index, which enabled the correct classification of 79 and 89% of the patients pre- and post-high ligation, respectively, was suggested to be a good indicator for varicocele which affects the fertility potential. Males exhibiting idiopathic impairment of sperm acrosome and nucleus were found to be potential responders to FSH treatment, whereas patients exhibiting low sperm activity proved to be good candidates for acupuncture treatment. Indications for selecting the optimal appropriate assisted reproduction technique (ART) procedure were found: Patients with a low Natural Fertility Index should be recommended for ART. A first choice ART selection should be performed according to an ART index based on the ultramorphological examination of the tail axoneme. The above index enabled correct prediction of 78% of the patients who achieved pregnancy following conventional ART (intrauterine insemination or IVF) and 74% of those whose wives conceived only following intracytoplasmic sperm injection. QUM sperm analysis is clinically informative, nontraumatic, and in the long run also cost-effective. This analysis should be performed when the male infertility factor cannot be clearly diagnosed by routine tests and prior to the first ART trial.

Relationship between human sperm lipid peroxidation, comprehensive quality parameters and IVF outcome

The membranes of human spermatozoa contain an extremely high concentration of polyunsaturated fatty acids and are therefore susceptible to lipid peroxidation damage. The aim of this study was to retrospectively determine the association between the lipid peroxidation levels of washed spermatozoa, as indicated by thiobarbituric-acid-reactive substance concentration, and: (a) semen quality evaluated by basic routine, biochemical, cytological and quantitative ultramorphological analyses; (b) IVF fertilization rate. Semen samples from 45 male partners of couples who had been referred for IVF treatment due to a female infertility factor were evaluated for quality as well as for thiobarbituric-acid-reactive substance concentrations. The latter were found to have a negative correlation with total sperm count, semen volume, zinc/fructose ratio, and the integrity of sperm acrosome and axonema. It was suggested that lipid peroxidation has a deleterious effect on the ultramorphological status of the sperm cells and, thereby, on the male fertilization potential. The content of the seminal fluid, about 30% of which is produced by the prostate, may protect spermatozoa from this destructive process. A negative correlation was also found between thiobarbituric-acid-reactive substance concentrations and IVF fertilization rate. When the patients were subdivided into fertilizing (fertilization rate > 0%) and nonfertilizing (fertilization rate = 0%) subgroups (n = 33 and n = 12, respectively), the former exhibited significantly lower thiobarbituric-acid-reactive substance concentrations than the latter. A new IVF fertilization index based on the lipid peroxidation level was established. This index had a predictive power of 93% (94% sensitivity and 92% specificity). The clinical value of this index should be further verified.

Role of electron microscopy of sperm in the evaluation of male infertility during the era of assisted reproduction

OBJECTIVES

To determine whether there are indications for and benefits from electron microscopy (EM) of sperm during the era of assisted reproductive technology.

METHODS

The medical history, semen analyses, and EM findings of 55 patients with pure male-factor infertility were reviewed to determine: (1) which semen characteristics (seminal volume, sperm concentration, percent motility, and percent normal morphology) were associated with normal or abnormal ultrastructure as determined by EM, (2) whether EM findings correlated with success or failure of in vitro fertilization (IVF), and (3) whether EM could screen for potentially inheritable genetic disorders.

RESULTS

Principal EM diagnoses were normal sperm ultrastructure (11 of 55; 20%), tail abnormalities (21 of 55; 38%), necrospermia (12 of 55; 22%), acrosomal defects (9 of 55; 16%), neck abnormalities (1 of 55; 2%), and incomplete maturation (1 of 55; 2%). Every patient with an abnormal EM study had impaired motility (33% or below) and abnormal morphology (13% or lower normal forms by World Health Organization criteria). The percentage of normal sperm morphology differed significantly across EM diagnoses (P < 0.0001). Differences in motility across the groups could not be detected because EM was only performed on patients with impaired motility. Although the partner of 1 patient with a normal EM study who underwent IVF achieved pregnancy, 11 with abnormal EM studies failed to establish a pregnancy by IVF. Finally, 5 (11%) of 44 patients with abnormal EM findings were diagnosed with primary ciliary dyskinesia directly as a result of EM. In addition, 3 (6.8%) of the 44 patients with abnormal EM findings were diagnosed with complete acrosomal loss.

CONCLUSIONS

Patients with severely abnormal motility and morphology on routine semen analysis may benefit from EM study of sperm. Our data indicate that EM findings correlate with success or failure of IVF, and that EM can screen for potentially inheritable genetic disorders.

Percentage of normal sperm heads is significantly increased by Percoll separation of semen

The purpose of this study was to assess objectively the effects of Percoll separation on human sperm head morphometry. Semen samples were washed and smears were prepared on slides. An aliquot of each sample was centrifuged on a Percoll gradient and spermatozoa were prepared on slides. Dimensions of sperm heads from each sample were assessed by computer-aided sperm head morphometry analysis and manual sperm morphology was assessed for each sample. The percentage of normal sperm heads and morphometric dimensions from washed and post-Percoll separated samples were compared across all men by a paired t-test. Correlations between normal sperm head morphometry and manual sperm morphology were assessed in washed and Percoll-separated samples. The percentage of normal sperm head morphometry was significantly (p < 0.001) higher in Percoll-separated samples than in washed samples (23.6 vs. 12.6%). No differences (p > 0.1) in mean sperm head measurements were detected between washed samples and Percoll-separated samples. Coefficients of variation for mean sperm head measurements were significantly lower in Percoll-separated samples. No correlation (p > 0.1) in percentage normal was found between computer-assisted sperm head morphometry and manual morphology for washed and post-Percoll samples. These results indicate that percentage normal sperm head morphometry is increased by Percoll separation. While sperm head dimensions were unchanged, sample variability was decreased.

Submicroscopic mathematical evaluation of spermatozoa in assisted reproduction. 2. In vitro fertilization. (Notulae seminologicae. 7)

This paper belongs to a series of applications of the Baccetti et al. formula (1) to the submicroscopical mathematical examination of human spermatozoa used for assisted reproduction. The present experiment concerns IVF, a technique requiring careful evaluation of sperm quality to predict the success of the program. Our results demonstrate that the sperm submicroscopic characters introduced in the formula are clearly correlated with the result of IVF. In fact the two numbers concerning sperm quality (percentage of spermatozoa free from structural defects and total number in the ejaculate of spermatozoa free from defects) obtained in successful and unsuccessful IVF groups, showed a large difference. The t distribution in both cases reached a significance of 0.005. The synthetic parameters obtained are therefore a good tool in the prediction of sperm power in in vitro insemination techniques. The most important characteristics seem to be the quality of the acrosomal complex, the status of the chromatin, the shape of mitochondria, the axonemal pattern, and the membrane integrity. All these characteristics are expressed with largely different means in successful and unsuccessful ejaculates (t distribution significant at 0.005). All these data confirm that submicroscopic mathematical diagnosis offers a convincing evaluation of sperm structure and function, involving all organelles, including acrosome function and cell motility. It is also demonstrated that sperm quality is a major factor in the success of IVF and that it is clearly revealed by the integrity of the majority of the sperm organelles.

Are the characteristics of spermatozoa in the insemination medium useful for predicting in-vitro fertilization results?

To determine whether the characteristics of Percoll-selected spermatozoa are more predictive of in-vitro fertilization (IVF) results than are those of native semen, 118 semen samples from patients undergoing an IVF attempt were studied. Motility, using computer-assisted sperm analysis, and morphology were recorded before and after sperm selection on a Percoll gradient. Percoll selection increased the percentage of morphologically normal spermatozoa (58.2 +/- 19.9% versus 47.9 +/- 17.9%; p < 0.0001). This increase concerned almost all abnormalities and especially abnormalities of the midpiece (cytoplasmic droplets and bent tails). However, morphology of spermatozoa in the Percoll fraction had the same predictive value for IVF as did that for whole semen. Concerning motility, all parameters, except linearity, were improved by Percoll preparation, and their predictive value for IVF results was significantly higher in the Percoll fraction than in native semen. Therefore, it is concluded that, even if sperm characteristics are improved dramatically after Percoll selection, only motility analysis then gave more practical information than did analysis of sperm characteristics in native semen. This suggests that impairment of spermiogenesis, which presumably induces sperm abnormalities, is more important than are the actual characteristics of the spermatozoa.

There is no relationship between concentration, motility and vacuolated cells

To determine whether there are differences between concentration and motility in the vacuolated spermatozoa of fertile donors, randomized men and infertile patients, semen samples were compared. Based on the percentages of concentration and motility, samples were divided into three groups: Group I, fertile donors, concentration > 20 x 10(6)/ml, motility > 50%; Group II, patients, concentrations < 20 x 10(6)/ml, motility < 50%; Group III, randomized men, concentration > 20 x 10(6)/ml, motility > 50%. In each group samples were assessed morphologically by the strict criteria of Kruger et al. The results showed that there was no difference between Group I and Group II, but there were differences between Group III and Group II, and Group III and Group I. We conclude that there is no relationship between concentration, motility and vacuolated cells.

Relevance of acrosome function in the evaluation of semen in vitro fertilizing ability

OBJECTIVES

To determine whether or not acrosome evaluation can enhance the prediction of IVF results when associated to conventional semen parameters.

DESIGN

Acrosome reaction, sperm concentration, motility, and morphology were recorded in 131 semen samples from patients undergoing an IVF attempt.

MAIN OUTCOME MEASURES

Spontaneous acrosome loss after a 24-hour incubation in B2 medium and after induction by calcium ionophore A23187 and phorbol ester, phorbol 12-myristate 13-acetate 4-O-methyl ether (TPA).

RESULTS

Statistically significant differences between fertilization failures and successes were found for concentration, viability, spontaneous and induced acrosome reaction, and most parameters of motility and morphology. However, none of the parameters could predict > 64% of IVF results when studied alone. A progressive discriminant analysis allowed to predict up to 83% of IVF results, by classifying sperms through their normal forms, rapid motility, spontaneous acrosome loss, enlarged heads, multiflagellar forms, vitality, linear motility, and acrosome response to TPA. The other parameters, including concentration and response to calcium ionophore, had no additive value.

CONCLUSION

The study of acrosome function, through spontaneous acrosome loss and response to TPA, is of great interest in clinical practice when associated to some parameters of motility and morphology. However, it appears that response to calcium ionophore, one of the most studied parameters, is of poor practical interest.

The nuclear status of human sperm cells

In the last decade, and in particular since the development of in vitro fertilization techniques, the nuclear status of human sperm cells has shown to be a key parameter in the assessment of male fertility. The shape and condensed state of the mature sperm nucleus are determined by structural and functional events that occur during spermiogenesis. This paper reviews essential findings on re-organization of the nucleus during sperm differentiation and maturation, and reports recent data on the architecture, biochemical composition and stability of the nucleus in human ejaculated spermatozoa. Different methods used to evaluate nuclear maturity in relation to male fertility are critically appraised.

Sperm quality of subfertile males before and after treatment with human follicle-stimulating hormone

OBJECTIVE

To assess the potential of short-term systemic administration of FSH for improving sperm quality, including ultrastructure, in teratozoospermic patients having normal endocrine profiles.

DESIGN

Semen parameters were assessed prospectively using light microscopy (LM), biochemical analysis, and quantitative ultramorphological analyses within 2 months before FSH administration and within 5 days after the end of treatment.

SETTING

Samples were collected from patients who were referred to the male fertility clinic at Bar-Ilan University.

PATIENTS

Thirty-one patients with teratozoospermia who exhibited normal hormonal profiles and who failed to fertilize their wives in at least two previous IVF attempts (n = 17) or who had wives with apparent normal fertility unable to conceive for > or = 5 years (n = 14) were classified as subfertile. One hundred one males with no previous history of infertility, whose wives conceived after < or = 12 months of pregnancy expectation, served as the control group.

INTERVENTION

Treatment was 75 IU FSH administered daily for 30 days.

MAIN OUTCOME MEASURES

Pretreatment and post-treatment sperm evaluation of basic and quantitative ultramorphological analyses parameters. The hypothesis was FSH treatment may improve spermatid morphogenesis by its multiple actions on the Sertoli-gamete cell compartment without interfering with the testicular hormonogenic function.

RESULTS

A significant improvement in agenesis of the acrosome and in the amorphous heads was observed, reaching normal values after treatment with FSH. The axonema deteriorated. No significant changes were observed in basic semen analysis parameters.

CONCLUSIONS

Because malformations of the fine structure of the sperm head subcellular organelles seem to be prerequisites for the success of FSH treatment, ultramorphological examination of the sperm may serve as an indication for the probability of success of this treatment.

A quantitative study of sperm head ultrastructure in subfertile males with excess sperm precursors

OBJECTIVE

To make an objective comparison between sperm head ultrastructure in fertile subjects and a subfertile cohort with an excess of immature germinal elements in the ejaculate.

DESIGN

A quantitative analysis of ultrastructural features of the sperm head using transmission electron microscopy in the defined groups.

PATIENTS

Ten men of proven fertility as controls and 10 subfertile subjects with a persistent excess of sperm precursors in the ejaculate were investigated.

SETTING

The Infertility Clinic at Queen Charlotte's and Chelsea Hospital, London.

MAIN OUTCOME MEASURES

Each individual in the study achieved a score for a range of previously defined features of sperm head ultrastructure. These scores provided the basis for comparison between fertile and subfertile subjects.

RESULTS

Subfertile individuals were found to have motile sperm with significantly more hypoplastic, detached, and abnormally shaped acrosomes than fertile controls. Sperm nuclei in these subjects also contained significantly more intranuclear vacuoles and immature chromatin and were associated more commonly with cytoplasmic droplets than fertile controls.

CONCLUSION

Men with an excess of sperm precursors in the ejaculate have motile sperm with a range of abnormalities involving the nucleus and acrosome to account for reduced functional competence.

Relation of human sperm acrosin activity and fertilization in vitro

The aim of the study described here was to determine the possible contribution of the acrosin activity test to routine semen analysis in enhancing the precision of the prognosis of IVF success in a group of patients in which the contribution of the egg factor to infertility was ruled out (20 cases) compared to a control IVF group (39 cases). Semen analysis, acrosin activity and acrosome ultrastructure were determined for all semen samples. The group with high fertilization rates was comprised of normozoospermic patients while the group with low fertilization rates was comprised of astheno-teratozoospermic patients. The mean acrosin level of the positive IVF group was significantly higher than that of the negative group (51.7 +/- 33.2 and 28.6 +/- 13.7, respectively). Two parameters: per cent motile spermatozoa and acrosin level, were found to have a significant positive correlation with subsequent successful IVF (r = 0.36, P < 0.006; r = 0.37, P < 0.004, respectively); and agenesis of the acrosome was found to have a significant negative correlation (r = -0.33, P < 0.01). The ability of these parameters to correctly predict fertilization success was 59%, with 5% false positive, among which 15.4% was predicted solely by the acrosin level (above 54 microIU 10(6) cells-1) and 23% solely by per cent motile spermatozoa (above 50%). Abnormalities of the acrosome ultrastructure did not contribute further to the correct classification. The apparent clinical benefit of the acrosin level test is discussed.