Protective effect of the immunomodulator AS101 against cyclophosphamide-induced testicular damage in mice.

BACKGROUND: Cyclophosphamide (Cy), a widely used anticancer drug, is associated with significant testicular damage and sterility. Co-administration of the immunomodulating compound AS101 during chemotherapy treatments was previously shown to protect organs against cytotoxic damage, without attenuating the drug's anticancer effect. In this animal study, we investigated the effect of AS101 on testicular damage, sperm DNA damage and infertility induced by Cy. Akt and glycogen synthase kinase-3beta (GSK-3beta) phosphorylation were investigated as a possible chemoprotective mechanism. METHODS: Mature male mice, 10 in each group, were injected intraperitoneally with 200 mg/kg Cy once a week for 5 weeks, with or without concurrent treatment with 10 microg per mouse AS101 three times per week. Damage to testicular tubules and sperm production was determined, sperm chromatin damage was analyzed and fertility was gauged. Akt and GSK-3beta phosphorylation were evaluated. RESULTS: Co-treatment with AS101 during the course of Cy administration significantly reduced the percentage of damaged seminiferous tubules (76.0 +/- 10.8% versus 40.3 +/- 2.6%), and reduced sperm DNA fragmentation (%DFI) from 44.7 +/- 1.0% to 25 +/- 6.5%. Co-treatment with AS101 also partially protected against the decrease in numbers of impregnated females and litter size. AS101 increased Akt and GSK-3beta phosphorylation. CONCLUSIONS: Our results indicate that AS101 can significantly protect against Cy-induced testicular damage and sperm DNA damage, probably by acting through Akt/GSK-3beta phosphorylation.

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

Influence of visible light and ultraviolet irradiation on motility and fertility of mammalian and fish sperm.

OBJECTIVE: The effects of visible light irradiation on sperm motility, fertility, and reactive oxygen species (ROS) formation were investigated and compared in ram and fish (tilapia). BACKGROUND DATA: Low-energy visible light has previously been found to modulate various processes in different biological systems. In the literature, it is accepted that the first step following visible light irradiation is the formation of ROS by endogenous cellular photosensitizers. METHODS: Sperm of ram and tilapia were irradiated with various light sources (400-800 nm white light, 660 nm red light, 360 nm blue light, 294 nm UV), and their motility and fertility rates were measured. The amount of ROS generated by irradiation was estimated using electron paramagnetic resonance (EPR) technique. RESULTS: Sperm taken from tilapia showed higher motility and fertility following red and white light irradiation. In contrast, the motility and fertility of ram sperm were slightly increased only by red light. A negative effect on motility and fertility of sperm of both species was obtained following irradiation with UV and blue light. The amount of ROS produced in irradiated tilapia sperm was much higher than that of ram sperm. CONCLUSIONS: The results show that different wavelengths differentially affect tilapia and ram sperm motility and fertilization. The difference in response to the various light sources might be explained by the different amounts of ROS formation by ram and tilapia, which are in agreement with the physiology of fertilization appropriate to each of these species. Based on these results, it is suggested that in vitro fertilization in mammals should be performed in darkness or at least under red light.

Acrocentric centromere organization within the chromocenter of the human sperm nucleus.

It has recently been reported that in human sperm cells, the centromeres are clustered in a chromocenter in the interior region of the nucleus. The aim of the present study was to determine the intra-chromocenter organization of the five centromeres of the acrocentric chromosomes responsible for the biosynthesis of rRNA. The acrocentric centromeres were labeled by fluorescence in situ hybridization (FISH) after mild decondensation of the sperm nuclei to preserve the tail structure. The tail was used as a topographical marker for the orientation of the nucleus. The following results were obtained: (a) the association among the five centromeres was higher than expected from random distribution; (b) all the centromeres observed were randomly located within the chromocenter, occupying about 87% of the total area of the internal nucleus; (c) a major subpopulation of centromeres was located in a preferred area occupying 8.3% of the total nuclear area, with a peak 0.6 microm on the lateral axis and 1.0 microm on the apical side of the longitudinal axis; and (d) The dispersion of the centromeres was not influenced by the degree of the nuclear decondensation. We conclude that in human sperm nuclei, the acrocentric centromeres are organized within a nonlocalized structural element in the chromocenter. The chromocenter can range from an expanded size of 87% of the whole nucleus to a preferred size of 8.3% independent of the degree of nuclear decondensation. These findings have important implications for nuclear function (rRNA) that is not directly related to sperm cell function or early embryo development.

Interchromosomal effect leading to an increase in aneuploidy in sperm nuclei in a man heterozygous for pericentric inversion (inv 9) and C-heterochromatin.

We describe a man with pericentric inversion 9 and constitutive heterochromatin, and a high disomy rate in his sperm cells (with all probes analyzed). The disomy rate was estimated with the following probes: 8, 9, 18, X, and Y, and was significantly higher than that in control sperm cells, while chromosome 9 showed the highest disomy frequency. The probes of X and Y together showed the same disomy frequency as X and Y alone, which indicates the same nondisjunction rate in the first meiotic division. We suggest that the interchromosomal effect found in this man differed from other findings in sperm cells of men carrying an inversion in terms of the difference in the length of the heterochromatin between the two chromosomes 9. Also, it is well known that the effect of inversion 9 with increased heterochromatin is highly variable and may even vary in members of the same family.

Dual energy metabolism-dependent effect of Ureaplasma urealyticum infection on sperm activity.

Genital Ureaplasma urealyticum infection is considered a sexually transmitted infection. It has long been debated whether the presence of U. urealyticum in semen may be a possible cause of infertility. Long-term incubation (4 hours or overnight) of sperm cells with U. urealyticum in vitro resulted in a significant inhibition of sperm motility and membrane alteration whereas a short incubation (45 minutes) of sperm cells with ureaplasmas resulted in an acceleration of sperm velocity. The aim of this study was to understand these contradictory reports of U. urealyticum infection on sperm motility. Spermatozoa from fresh ejaculates of normozoospermic semen of men who were referred to the university Male Fertility Laboratory for semen analysis, with no history of genital tract infection, and from normal Assaf breed rams were infected in vitro with U. urealyticum serotype 8, at different pHs and O2 concentrations. Sperm viability and motility and changes in extracellular pH were evaluated. A significant (16%-43%) increase in sperm activity was observed upon infection at alkaline pH (7.8) under aerobic or hypoxic conditions, and a 58% increase was observed under anaerobic conditions and pH 7.2. When the infection was conducted under aerobic conditions and acidic pH (6.3), or under hypoxic conditions at neutral pH (7.2), an 8%-25% inhibition of sperm activity was observed. These results indicate that when sperm activity depends on mitochondrial oxidative phosphorylation, usually at low pHs, U. urealyticum competes with mitochondrial energy production and therefore reduces sperm motility and viability. However, when sperm energy metabolism depends on glycolysis, usually at higher pHs, U. urealyticum stimulates glycolysis and sperm activity.

In vivo and in vitro impairment of human and ram sperm nuclear chromatin integrity by sexually transmitted Ureaplasma urealyticum infection.

The incidence of Ureaplasma urealyticum infection in the semen of infertile men is variable (7%-42%). Evidence has accumulated through routine semen analysis to suggest that this infection can cause embryo loss without necessarily affecting sperm quality. The aim of this study was to specifically investigate the effects of U. urealyticum infection on sperm chromatin stability and DNA integrity, which are known to be correlated to pregnancy outcome. Sperm cells isolated from human semen infected in vivo with U. urealyticum exhibited a low percentage of stable chromatin as determined by nuclear chromatin decondensation assay (42% +/- 4.8%, n = 8) and a high percent of denatured DNA as determined by sperm chromatin structure assay (60.9% +/- 9.1%, n = 7). After doxycyclin treatment, a significant improvement in both parameters was observed (73.7% +/- 3.6%, P: < 0.001 and 30.1% +/- 3.5%, P: < 0.008, respectively). Sperm cells infected in vitro exhibited higher rates of viability and motility than uninfected cells. In contradistinction, U. urealyticum caused significant dose- and time-dependent chromatin decondensation and DNA damage. The percentage of human sperm cells with denatured DNA increased significantly by 54.9% +/- 23.9% and 47. 9% +/- 12.1%, after 30 min infection with serotypes 8 and 3, respectively, at a multiplicity of infection of 100 ureaplasmas per sperm compared with uninfected control cells. The damage to DNA was significantly more pronounced in infected ram sperm (180.9% +/- 21. 5%). These results indicate that preserved sperm activity post U. urealyticum infection resulted in damage to paternal DNA, although a high fertilization rate was maintained, and embryonic development may, therefore, be impaired.

Sperm ultramorphology as a pathophysiological indicator of spermatogenesis in males suffering from varicocele.

Varicocele of spermatic veins is considered to be one of the major causes of male infertility associated with reduction of sperm quality. The pathophysiology of this condition is not yet completely understood. The aim of this study was to shed light on the pathophysiology of varicocele by identifying semen parameters, especially sperm ultramorphology, which improve following high ligation of the spermatic vein. Seventy-five males with diagnosed varicocele were included in this study. Semen parameters were assessed prospectively using light microscopy, semen biochemistry and sperm quantitative ultramorphological analysis, before high ligation and 3-9 months after high ligation. The control group consisted of twenty-five untreated varicocele patients who underwent two semen examinations within 3-9 months. No statistical difference in any of the examined variables was found between the two examinations in the control group. The treated patients exhibited a significant improvement in sperm density, progressive motility, percentage of normally formed spermatozoa, agenesis of sperm acrosome, chromatin condensation and incidence of amorphous heads compared with the pretreatment condition (P < or = 0.01). In contradiction, no significant improvement was observed following treatment in any of the sperm tail subcellular organelles. It is concluded that varicocele may cause deleterious alterations in early spermatid head differentiation during spermiogenesis and that varicocele patients with a high incidence of sperm acrosome and nucleus malformations are appropriate candidates for varicocele correction.

Does acupuncture treatment affect sperm density in males with very low sperm count? A pilot study.

Classic therapies are usually ineffective in the treatment of patients with very poor sperm density. The aim of this study was to determine the effect of acupuncture on these males. Semen samples of 20 patients with a history of azoospermia were examined by light microscope (LM) and scanning electron microscope (SEM), with which a microsearch for spermatozoa was carried out. These examinations were performed before and 1 month after acupuncture treatment and revealed that the study group originally contained three severely oligoteratoasthenozoospermic (OTA), two pseudoazoospermic and 15 azoospermic patients. The control group was comprised of 20 untreated males who underwent two semen examinations within a period of 2-4 months and had initial andrological profiles similar to those of the experimental group. No changes in any of the parameters examined were observed in the control group. There was a marked but not significant improvement in the sperm counts of severely OTA males following acupuncture treatment (average = 0.7 +/- 1.1 x 10(6) spermatozoa per ejaculate before treatment vs. 4.3 +/- 3.2 x 10(6) spermatozoa per ejaculate after treatment). A definite increase in sperm count was detected in the ejaculates of 10 (67%) of the 15 azoospermic patients. Seven of these males exhibited post-treatment spermatozoa that were detected even by LM. The sperm production of these seven males increased significantly, from 0 to an average of 1.5 +/- 2.4 x 10(6) spermatozoa per ejaculate (Z = -2.8, P < or = 0.01). Males with genital tract inflammation exhibited the most remarkable improvement in sperm density (on average from 0.3 +/- 0.6 x 10(6) spermatozoa per ejaculate to 3.3 +/- 3.2 x 10(6) spermatozoa per ejaculate; Z = -2.4, P < or = 0.02). Two pregnancies were achieved by the IVF-ICSI procedure. It is concluded that acupuncture may be a useful, nontraumatic treatment for males with very poor sperm density, especially those with a history of genital tract inflammation.

Follicle-stimulating hormone treatment for men with idiopathic oligoteratoasthenozoospermia before in vitro fertilization: the impact on sperm microstructure and fertilization potential.

OBJECTIVE: To assess the effect of FSH on sperm fertilization potential and sperm intracellular structure in men with oligoteratoasthenozoospermia and a proven low fertilization rate in IVF. DESIGN: Prospective, randomized, partial crossover study. SETTING: IVF Unit, Golda Campus, Rabin Medical Center, Petah Tikva, Israel. PATIENT(S): Forty normogonadotropic, normogonadal men with oligoteratoasthenozoospermia and at least one previous IVF attempt in which fertilization failed or the fertilization rate was <30%. INTERVENTION(S): The men were randomly assigned to treatment with daily injections of 75 IU of FSH or 150 IU of FSH for at least 60 days before IVF treatment. A control group of men underwent an IVF cycle without treatment and then were randomly assigned tojoin group 1A or 1B for an additional IVF cycle with treatment. MAIN OUTCOME MEASURE(S): LH, FSH, and testosterone levels during FSH treatment, evaluation of ultramorphologic changes in sperm by electron microscopy, and comparison of fertilization rates in the control and study groups. RESULT(S): After treatment with 75 IU or 150 IU of FSH, the mean fertilization rates were 19.7% and 20.5%, respectively, compared with a 5.8% fertilization rate in the study control cycles. CONCLUSION(S): Prolonged treatment with FSH results in a significant increase in fertilization rates. This effect may be related to improvements in subcellular components of the sperm.

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.

ART success and in vivo sperm cell selection depend on the ultramorphological status of spermatozoa.

Management of male infertility has recently shifted from treatment of the subfertile man towards techniques of assisted reproduction (ART). This study aimed to evaluate the possible role of the ultramorphological status of the spermatozoon with respect to sperm selection in vivo and prediction of ART success. Ultramorphological sperm parameters were assessed retrospectively for 92 males with sufficient sperm density (10(7) spermatozoa ejaculate-1) whose wives conceived following a stepwise discarding of the female genital tract barriers, using intra-uterine insemination (IUI) (n = 26), in vitro fertilization (IVF) (n = 45) or intracytoplasmic sperm injection (ICSI) (n = 21). In parallel, sperm samples of 71 fertile males were examined. Normal ultramorphology of all head and tail subcellular organelles was found to be essential for the ability of spermatozoa to pass the lower female genital tract. The ultramorphological migration threshold for this barrier is apparently higher than that essential for oocyte fertilization. No specific indication associated with passage through the upper genital tract was found. A high prevalence of axonema defects was found to impair the ability of sperm cells to penetrate the oocyte investment. The natural fertility index, based on routine sperm parameters and the ultrastructural status of the spermatozoon's subcellular organelles was confirmed to be beneficial for directing patients to ART. A discriminative score based on axonema integrity was found to contribute additional information for the first choice decision between conventional ART and ICSI (75% prediction ability). Thus it may be helpful in finding the simplest and least expensive procedure with the greatest long-term chance for pregnancy.

Does glucose affect fertilization, development and pregnancy rates of human in-vitro fertilized oocytes?

The study was conducted to examine whether the presence of glucose in the incubation medium affects fertilization, development and implantation rates of human oocytes of patients who were attending our in-vitro fertilization programme. Harvested oocytes were transferred into one of four different media: human tubal fluid (HTF), P1, M3 and IVF-Universal (IVF-Med). Three of these contained glucose; the fourth (P1), contained no glucose or phosphate ions. In an independent preliminary study, some of the oocytes of each patient were incubated in IVF-Med, which lacks phosphate ions, but not glucose. Comparisons of fertilization rates between media pairs showed differences among all pairs except HTF and M3. When comparing the four study groups, no difference was noticed in embryo development or embryo quality 48 h post-ovum retrieval. A higher development rate was demonstrated in embryos incubated in M3 medium, in comparison with the P1 and IVF-Med embryos after incubation for 72 h. No difference in pregnancy rate was found after embryo transfers of preimplantation embryos which were incubated in one of the following media: HTF, M3 and IVF-Med (seven out of 22, 18 of 54 and 32 of 69 treatment cycles respectively). A lower incidence of pregnancies occurred following transfers of embryos which were incubated in P1 medium (seven pregnancies out of 37 cycles). We suggest that the presence of glucose in the incubation medium enhances implantation potential of in-vitro-developing preimplantation embryos.

Effect of acupuncture on sperm parameters of males suffering from subfertility related to low sperm quality.

The aim of this prospective controlled study was to assess the effect of acupuncture on the sperm quality of males suffering from subfertility related to sperm impairment. Semen samples of 16 acupuncture-treated subfertile patients were analyzed before and 1 month after treatment (twice a week for 5 weeks). In parallel, semen samples of 16 control untreated subfertile males were examined. Two specimens were taken from the control group at an interval of 2-8 months. The expanded semen analysis included routine and ultramorphological observations. The fertility index increased significantly (p < or = .05) following improvement in total functional sperm fraction, percentage of viability, total motile spermatozoa per ejaculate, and integrity of the axonema (p < or = .05), which occurred upon treatment. The intactness of axonema and sperm motility were highly correlated (corr. = .50, p < or = .05). Thus, patients exhibiting a low fertility potential due to reduced sperm activity may benefit from acupuncture treatment.

Semen Quality of Workers Exposed to Ionizing Radiation in Decontamination Work after the Chernobyl Nuclear Reactor Accident.

The objective of the study was to assess effects of radiation on sperm quality, including ultramorphology of spermatozoa of men who worked as salvage workers at the Chernobyl nuclear reactor accident site or in the adjacent region. Semen characteristics were assessed by light microscopy, biochemical analysis, and quantitative ultramorphologic analysis seven years after the accident. Samples were collected in the Ukraine, examined there by routine semen analysis, fixed, and transferred to Israel for further examinations. The study population consisted of 18 radiation-exposed individuals. Eighteen unexposed Ukrainian men were examined as controls. Sperm motility was found to be reduced in the radiation-exposed workers. Ultramorphologic defects were evident in the sperm nucleus. Fertility potential was adversely affected among the exposed workers. Thus, salvage workers who had worked at the Chernobyl nuclear reactor accident site or in the vicinity thereof were found to manifest ultramorphologic abnormalities in the sperm nucleus and to have impaired fertility potential seven years after the radiation exposure. The injury was independent of whether the work site had been located at the reactor site or in the vicinity thereof.

[Seminiferous tubule cytological pattern in infertile, azoospermic men in diagnosis and therapy].

We determined spermatogenic patterns of seminiferous tubules in azoospermic infertile men and evaluated the prevalence of bilateral testicular homogeneity. 185 azoospermic men underwent bilateral testicular fine-needle aspiration (TFNA) in which each testis was punctured at 3 different positions. Aspirated material was stained and classified according to the most mature spermatogenic cell type present or whether only Sertoli cells were present. 35.7% had spermatozoa in their testes, 36.2% had spermatogenic maturation arrest, and 28.1% had only Sertoli cells in their seminiferous tubules. In 15.6% of all patients, the diagnosis in 1 testis differed from that in the other. In only 73.2% of those with testicular spermatozoa was it bilateral. In the remaining 26.9%, only Sertoli cells, spermatocytes or spermatids were found as the most mature cell type in the other testis. The study definitely indicates that fertilization with retrieved testicular spermatozoa should not be offered to azoospermic patients without prior evaluation of the seminiferous tubuespermatogenic pattern in both testes.