Spermatocyte Stage Research Articles

Changes in crossover distribution along a quadrivalent in a man carrier of a reciprocal translocation t(11;14)

A testicular biopsy from an infertile man carrying a heterozygous chromosome translocation t(11;14) was studied with synaptonemal complex analysis and immunolocalization of the protein MLH1 for crossover detection. A full blockage of spermatogenesis at the spermatocyte stage was related to the presence of the translocation quadrivalents at pachytene. Only 2% of the quadrivalents showed full synapsis. Most of the spermatocytes showed asynaptic free ends that frequently mingled with the XY pair. The average number of crossovers per cell was diminished from a mean of 52.7 in controls to a mean of 48 in the patient. The difference between the number of crossovers in the quadrivalent and the normal bivalents was highly significant. The distribution of crossovers over the segment of the quadrivalent corresponding to bivalent #14 was also very different from that of the control. It is concluded that in this translocation, the pattern of crossovers is changed, mainly due to a synaptic hindrance in the quadrivalent, and that the spermatogenesis arrest is mainly due to the quadrivalents that interact with the XY pair.

Influence of stress on gonadotrophin induced testicular recrudescence in the lizardMabuya Carinata

Administration (ip) of FSH (10 IU/0.1 ml distilled water (dw)/lizard/alternate days/30 days) to adult male lizards, Mabuya carinata, during the early recrudescence phase of the reproductive cycle caused activation of spermatogenic and steroidogenic activity of the testis, as shown by a significant increase in mean number of spermatogonia, primary spermatocytes and spermatids, and serum levels of testosterone, as compared to initial controls. In addition, there were abundant spermatozoa in the lumen of the seminiferous tubules. Interestingly, administration of a similar dosage of FSH to lizards exposed to stressors (handling, chasing, and noise randomly applied, five times a day for 30 days) resulted in a significant increase in mean number of spermatogonia and primary spermatocytes over initial control values, whereas the number of secondary spermatocytes and spermatids and serum levels of testosterone did not significantly differ from those of initial controls, and were significantly lower than FSH treated normal lizards. Further, spermatozoa were infrequently found in the seminiferous tubules of these lizards. Treatment controls (receiving 0.1 ml dw/lizard/alternate days for 30 days) did not show significant variation in mean number of spermatogonia, spermatocytes and spermatids, and serum levels of testosterone from initial controls. Another group of lizards was exposed to stressors and did not receive FSH. These lizards showed a significant decrease in mean number of secondary spermatocytes compared to treatment controls and all other parameters did not significantly differ from those of both control groups. The results reveal that gonadotrophin-induced spermatogonial proliferation occurs under stressful conditions, whereas progress of spermatogenesis beyond primary spermatocyte stage is impaired due to inhibition (under stress) of gonadotrophin induced steroidogenic activity in M. carinata.

DECREASED TESTICULAR EXPRESSION OF cAMP RESPONSE ELEMENT MODULATOR (CREM) IN RAT WITH VARICOCELE

This study examines the hypothesis that varicocele would impair the testicular expression of cAMP response element modulator (CREM) in experimental rats. Thirty (30) rats were selected at random, of 20 were operated as varicocele's group; of 10 were for sham-operation as controlled group, testes were removed, fixed and stained in three months. Makler Score was adopted to analyze the bore, limitan's thickness, layer number of cell, the degree of cell's maturity and average score in 200 and 100 seminiferous tubulae, respectively. CREM, HSP60 was determinated by hybridization in situ, the difference between two groups were compared. In varicocele group, seminiferous tubule's bore was decreased (101 +/- 2.2) vs 146 +/- 4.1), limitan became thicker (3.5 +/- 0.1 vs 1.9 +/- 0.2), cell's layer number was reduced (3.0 +/- 0.2 vs 5.5 +/- 0.1), cell's maturity turned to disturbance (3.6 +/- 0.3 vs 4.9 +/- 0.1), the average score was lower than controlled group (8.5 +/- 0.6 vs 16.0 +/- 1.2), they had significant differences (P < 0.001). The testicular CREM expression was significantly lower in varicocele group than in controlled one (VG2.0 +/- 0.32, SoG3.90 +/- 0.32) (p < 0.001), which was located in spermatogenous cell to spermatocyte stage. However, HSP60 expression in VG was higher than in SoG (3.85 +/- 0.3 versus 2.1 +/- 0.32) with significant differences (P < 0.001), the expression located in spermatid. Varicocele could lead to lower testicular CREM expression and breeding sperm functional lesion.

A Targeted Mutation of Nkd1 Impairs Mouse Spermatogenesis

Nkd1 is an antagonist of the canonical Wnt/beta-catenin signaling pathway. The EF-hand motif of Nkd1 is required for its inhibitory function. Early studies suggested that Nkd1 might play important roles in mouse embryonic development and tumorigenesis. We constructed Nkd1(-/-) mice whose Nkd1 protein lacked the EF-hand and was unable to inhibit Wnt/beta-catenin signaling. The homozygotes were viable and grew normally, but their fertility in males was reduced. In wild-type adult testes, Nkd1 mRNA was expressed more abundantly in the elongating spermatids than in the round spermatids. Lack of EF-hand caused reductions in the testis weight and sperm count by 30 and 60%, respectively. During testis development, Nkd1 mRNA expression started at the 25th day after birth, coincident with the onset of Wnt1 expression. Nuclear localization of beta-catenin increased in the elongating spermatids, suggesting that the mutant Nkd1 failed to inhibit the Wnt/beta-catenin pathway. These results suggest that deletion of the EF-hand from Nkd1 reduces the number of the elongating spermatids at haploid stage. In contrast, the mutant Nkd1 did not affect intestinal polyposis in Apc(Delta716) mice.

Stages and duration of spermatogenesis in the domestic ferret ( Mustela putorius furo)

Classification of seminiferous tubules is the basis for understanding normal and abnormal spermatogenesis. The aim of the present study was to determine spermatogenic stages and the duration of the cycle in the domestic ferret using bromodeoxyuridine (BrdU) as a tracer. Eleven adult male ferrets that were maintained in a breeding condition were used. Testicular sections were stained with the periodic acid-Schiff reaction for light microscopy. To determine the cycle duration, six ferrets were injected intraperitoneally with BrdU, and testes were collected 3 h later and 10 days and 3 h later. BrdU was detected by immunohistochemistry. Seminiferous tubules were classified into eight stages, and frequencies of stages I–VIII were 10.6, 2.2, 7.9, 13.1, 22.3, 21.9, 14.0 and 8.0%, respectively. The most advanced BrdU-labeled cells at 3 h post-injection were leptotene spermatocytes in stage VI and those at 10 days and 3 h were pachytene spermatocytes in stage V. From differences in stage frequency and BrdU staining frequency between two time points, the duration of one cycle was estimated to be 13.0 days. The present observations indicate that stages and the cycle duration of the ferret spermatogenesis are similar to those reported in other carnivores.

Effect of Saponins of Albizia lebbeck (L.) Benth bark on the reproductive system of male albino rats

Oral administration of saponins isolated from Albizia lebbeck bark at the dose level of 50 mg/kg/b.w. per day for 60 days to male rats brought about a significant decrease in the weights of testes, epididymides, seminal vesicle and ventral prostate. The production of round spermatid was reduced by 73.04% in Albizia lebbeck treated rats. The population of preleptotene spermatocytes and spermatogonia were reduced by 65.07% and 47.48% and secondary spermatocytes by 73.41%, respectively. Cross sectional surface area of Sertoli cells as well as the cell counts were found to be depleted significantly. Leydig cell nuclear area and number of mature Leydig cells were decreased by 57.47% and 54.42%, respectively. Sperm motility as well as sperm density were reduced significantly. Albizia lebbeck reduced the fertility of male rats by 100%. There were no significant changes in RBC and WBC count, haemoglobin, haematocrit and glucose in the blood and cholesterol, protein, triglyceride and phospholipid in the serum. The protein, glycogen and cholesterol contents of the testes, fructose in the seminal vesicle and protein in epididymides were significantly decreased. Histoarchitecture of the testes showed vacuolization at primary spermatocytes stage. Highly reduced seminiferous tubular diameter and increased intertubular space were also observed when compared to controls.

Cytological studies of meiotic recombination in human males

We combined immunostaining and fluorescence in situ hybridization (FISH) methodology to directly examine meiotic exchanges in over 2,000 pachytene stage spermatocytes from 25 individuals. Our results indicate that, on average, there are about 50 exchanges per cell and that, with the exception of the acrocentric chromosomes, all chromosome arms harbor at least one exchange. We also identified significant among-individual variation in the mean number of exchanges, with an approximate 20% difference between individuals with “low” and those with “high” exchange frequencies.

The cloning of cyclin B3 and its gene expression during hormonally induced spermatogenesis in the teleost, Anguilla japonica

We cloned cyclin B1, B2, and B3 cDNAs from the eel testis. Northern blot analysis indicated that these cyclin B mRNAs were expressed and increased from day 3 onward after the hormonal induction of spermatogenesis, and that cyclin B3 was most dominantly expressed during spermatogenesis. In situ hybridization showed that cyclin B1 and B2 were present from the spermatogonium stage to the spermatocyte stage. On the other hand, cyclin B3 mRNA was present only in spermatogonia. Although mouse cyclin B3 is expressed specifically in the early meiotic prophase, these results indicate that eel cyclin B3 expression is limited during spermatogenesis to spermatogonia, but is not present in spermatocytes. These facts together suggest that eel cyclin B3 is specifically involved in spermatogonial proliferation (mitosis), but not in meiosis.

Spermatocyte/Spermatid-specific Thioredoxin-3, a Novel Golgi Apparatus-associated Thioredoxin, Is a Specific Marker of Aberrant Spermatogenesis

Mammalian germ cells are endowed with a complete set of thioredoxins (Trx), a class of redox proteins located in specific structures of the spermatid and sperm tail. We report here the characterization, under normal and pathological conditions, of a novel thioredoxin with a germ line-restricted expression pattern, named spermatocyte/spermatid-specific thioredoxin-3 (SPTRX-3). The human SPTRX-3 gene maps at 9q32, only 50 kb downstream from the TRX-1 gene from which it probably originated as genomic duplication. Therefore, human SPTRX-3 protein comprises a unique thioredoxin domain displaying high homology with the ubiquitously expressed TRX-1. Among the tissues investigated, Sptrx-3 mRNA is found exclusively in the male germ cells at pachytene spermatocyte and round spermatid stages. Light and electron microscopy show SPTRX-3 protein to be predominately located in the Golgi apparatus of pachytene spermatocytes and round and elongated spermatids, with a transient localization in the developing acrosome of round spermatids. In addition, increased levels of SPTRX-3, possibly caused by overexpression, are observed in morphologically abnormal human spermatozoa from infertile men. In addition, SPTRX-3 is identified as a novel postobstruction autoantigen. In this report, we propose that SPTRX-3 can be used as a specific marker for diverse sperm and testis pathologies. SPTRX-3 is the first thioredoxin specific to the Golgi apparatus, and its function within this organelle might be related to the post-translational modification of proteins required for germ cell-specific functions, such as acrosomal biogenesis.

Association of meiotic arrest with lack of BOULE protein expression in infertile men.

Spermatogenesis is a complex developmental process of mitotic and meiotic cell divisions that ultimately results in production of haploid spermatozoa. Recent studies in flies demonstrate that the BOULE gene encodes a key factor of meiosis in male germ cells, regulating the expression of twine, a cdc25 phosphatase, which promotes progression through meiosis. In this study, we investigated whether a common mechanism underlies the block of germ cell maturation observed in idiopathic and nonidiopathic azoospermic patients with meiotic arrest. We examined, by immunohistochemistry, BOULE and CDC25A phosphatase protein, the human homolog of twine, expression in 47 men with meiotic arrest, mixed atrophy, or normal spermatogenesis. The presence of genetic alterations within the BOULE gene was investigated by single-stranded conformation polymorphism. BOULE protein expression in men with complete spermatogenesis can be restricted to stages from leptotene up to stages of late spermatocytes, whereas CDC25A expression ranges from leptotene spermatocytes to elongating spermatids. Although spermatocytes were present in all testicular biopsies with meiotic arrest (28 testes), BOULE protein expression was completely lacking. In addition, in nearly all biopsies in which BOULE was absent, CDC25A was concomitantly lacking. However, no mutations or polymorphisms in the BOULE gene were identified, which could explain the lack of BOULE or CDC25A expression. These results indicate that a major group of infertile men with meiotic arrest lack BOULE protein and its putative target, CDC25A expression. The spermatogenic failure seems to arise from factor(s) upstream of BOULE, which are possibly involved in regulating transcription and/or translation of BOULE. Thus, the spermatogenic damage leading to meiotic arrest is independent of the etiology and indicates that BOULE is a possible fundamental mediator of meiotic transition in the human.

Mili, a mammalian member of piwi family gene, is essential for spermatogenesis.

The piwi family genes, which are defined by conserved PAZ and Piwi domains, play important roles in stem cell self-renewal, RNA silencing, and translational regulation in various organisms. To reveal the function of the mammalian homolog of piwi, we produced and analyzed mice with targeted mutations in the Mili gene, which is one of three mouse homologs of piwi. Spermatogenesis in the MILI-null mice was blocked completely at the early prophase of the first meiosis, from the zygotene to early pachytene, and the mice were sterile. However, primordial germ cell development and female germ cell production were not disturbed. Furthermore, MILI bound to MVH, which is an essential factor during the early spermatocyte stage. The similarities in the phenotypes of the MILI- and MVH-deficient mice and in the physical binding properties of MILI and MVH indicate a functional association of these proteins in post-transcriptional regulation. These data indicate that MILI is essential for the differentiation of spermatocytes.

Effect of chronic low dose of methotrexate on cellular proliferation during spermatogenesis in rats.

This study was conducted to evaluate cellular proliferation of germinal and non-germinal elements of seminiferous tubules following continuous Day 1 to Day 17 exposure of methotrexate (12.5 microgram) in male rats. There was significant decrease in the diameter of seminiferous tubules (P < 0.10) followed by increase of interstitial space (P < 0.01). The size of various stages of primary, secondary spermatocytes, and spermatids was altered significantly compared to controls. Vacuolization/decondensation of "chromatin-mass" in spermatocytes changed from rounded to oval. The size of the Sertoli and Leydig cells were reduced significantly. Basement membrane at some places seems to be disrupted and thin in experimental testis. Methotrexate induced cytotoxicity on the proliferation of cellular contents of seminiferous tubules elucidating the mechanism of dose-dependent drug induced testicular damage during spermatogenesis.

Male infertility due to germ cell apoptosis in mice lacking the thiamin carrier, Tht1. A new insight into the critical role of thiamin in spermatogenesis

A mouse model of thiamin-responsive megaloblastic anemia (diabetes mellitus, deafness, megaloblastic anemia) lacking functional Slc19a2 has been generated and unexpectedly found to have a male-specific sterility phenotype. We describe here the characterization of the testis-specific effects of absence of the high-affinity thiamin transporter, Tht1. Null males were found to have hypoplastic testes secondary to germ cell depletion. Morphologic and expression analysis revealed that under conditions of standard thiamin intake, tissues affected in the syndrome (pancreatic β-cell, hematopoietic cells, auditory nerve) maintained normal function but pachytene stage spermatocytes underwent apoptosis. Under conditions of thiamin challenge, the apoptotic cell loss extended to earlier stages of germ cells but spared Sertoli cells and Leydig cells. Injection of high-dose thiamin was effective in reversing the spermatogenic failure, suggesting that the absence of the thiamin carrier could be overcome by diffusion-mediated transport at supranormal thiamin concentrations. These observations demonstrated that male germ cells, particularly those with high thiamin transporter expression beyond the blood–testis barrier, were more susceptible to apoptosis triggered by intracellular thiamin deficiency than any other tissue type. The findings described here highlight an unexpected and critical role for thiamin transport and metabolism in spermatogenesis.

Telomere attachment, meiotic chromosome condensation, pairing, and bouquet stage duration are modified in spermatocytes lacking axial elements.

During the extended prophase to the meiosis I division, chromosomes assemble axial elements (AE) along replicated sister chromatids whose ends attach to the inner nuclear membrane (NM) via a specialized conical thickening. Here, we show at the EM level that in Sycp3(-/-) spermatocyte chromosomes lack the AE and the conical end thickening, but still they attach their telomeres to the inner NM with an electron-dense plate that contains T(2)AG(3) repeats. Immunofluorescence detected telomere proteins, SCP2, and the meiosis-specific cohesin STAG3 at the Sycp3(-/-) telomere. Bouquet stage spermatocytes were approximately threefold enriched, and the number of telomere but not centromere signals was reduced to the haploid in advanced Sycp3(-/-) spermatocytes, which indicates a special mode of homolog pairing at the mammalian telomere. Fluorescence in situ hybridization with mouse chromosome 8- and 12-specific subsatellite probes uncovered reduced levels of regional homolog pairing, whereas painting of chromosomes 13 revealed partial or complete juxtapositioning of homologs; however, condensation of Sycp3(-/-) bivalents was defective. Electron microscopic analysis of AE-deficient spermatocytes revealed that transverse filaments formed short structures reminiscent of the synaptonemal complex central region, which likely mediate stable homolog pairing. It appears that the AE is required for chromosome condensation, rapid exit from the bouquet stage, and fine-tuning of homolog pairing.

Annual sex hormonal profiles, gonad development and age determination of the Mekong giant catfish (Pangasianodon gigas , Chevey)

Annual sex hormonal profiles, gonad development and age determination of 18 (13–14 kg body weight) and three (145–226 kg body weight) Mekong giant catfish (MGC) (Pangasianodon gigas, Chevey) reared in earthen ponds in Chiang Mai and from the Mekong River in Chiang Rai, Thailand, respectively, were investigated. The hormonal profiles were determined from blood samples of the fish by electrochemiluminescence immunoassay during May to August in 2000. The highest testosterone levels of 0.06 ng mL−1 in both sexes and the highest oestradiol of 47.8 and 14.23 pg mL−1 in females and males, respectively, were observed in May. The gonadosomatic index was found to be 0.07 for males and 0.38 for females from ponds in comparison with 2.27 for males and 8.29 for females from the Mekong River. Higher development stages of spermatocytes and oocytes of the cultured fish in May than in February and November were demonstrated. No mature germ cells were obtained from either the males or females, indicating no sexual maturity. The average age of fish was determined from the annual rings of the cross-section of the pectoral fins by a stereomicroscope. The average age of fish in earthen pond determined from the annual ring was 8 years, which agreed with the actual culture records, while those from the Mekong River were 21 years. This information will be beneficial for the breeding programmes and conservation of the MGC.

Annual cycle of testicular maturation in the helmet crab Telmessus cheiragonus

: To clarify the annual testicular maturation cycle in the helmet crab Telmessus cheiragonus, seasonal histological changes of the testis and occurrence of grasping pairs and recently copulated females with fresh sperm plugs were investigated. The testis was composed of seminiferous ducts with many testicular lobules. Development of the lobules was divided into six stages (spermatogonia proliferation, first spermatocyte, reduction division, spermatid, spermiogenesis and free sperm stage) based on the spermatogenic phase of the germ cells in each lobule. The mean percentage of the lobules during each stage was calculated every 1–3 months. Developed lobules occurred with a high percentage throughout the year except in June when developing lobules predominated. Grasping pairs and females with fresh sperm plugs were collected during April–July with a peak in May–June. These results suggest that the males have testis with many developing lobules in June when they are active for mating. Newly formed spermatozoa may be stored in the testis and the vas deferens until the next mating season after June, as the spermatozoa may not have an opportunity to fertilize eggs until the next season and there is no sign of spermatozoa absorption in the testis.

Normal spermatogenesis and fertility in germ cell-specific genomic androgen receptor knockout mice

Objective: The purpose of the present study is to generate the seprmatocyte specific androgen receptor knock out (ARKO) mice using cre-lox strategy and to study its influence on spermatogenesis. Design: A tissue-specific knock-out animal model. Materials and Methods: Previous, we have generated a strain of mice carrying a fragment of lox sequence within the androgen receptor genome (flox-AR). In the present study, we mated the flox-AR mice with a mice carrying cre recombinase driven by spermatocyte specific promoter synaptonemal complex protein 1 (Sycp1-Cre mice). Since Sycp1 is only expressed at the leptotene-zygotene stage of spermatocyte, the generated Sycp1-ARKO male mice lost androgen receptor at the process of spermatogenesis after leptotene-zygotene stage. We compared the wild type (wt) and the Sycp1-ARKO mice on the fertility, AR expression, sperm count and histology of seminiferous tubules to determine how the spermatogenensis was influenced. The efficiency of the knock-out is confirmed by checking the genotypes of female offspring from the Sycp1-ARKO fathers and the wt C57BL/6J mothers. Results: Histology analyses indicate that each stage of spermatogenesis is normal and the expression of AR in Sertoli, Leydig, and peritubular cells is unaffected in Sycp1-ARKO mice. Sperm count and motility in epididymis from Sycp1-ARKO are similar to that of the wt siblings. The overall knock-out efficiency is 78%. However, 3 of 4 Sycp1-ARKO mice show 100% efficiency. Conclusion: The results suggest that the expression of androgen receptor in the male germ cells beyond the spermatocyte stage is redundant for the sperm maturation.

Drosophila TGIF is essential for developmentally regulated transcription in spermatogenesis.

We have investigated the role of TGIF, a TALE-class homeodomain transcription factor, in Drosophila development. In vertebrates, TGIF has been implicated, by in vitro analysis, in several pathways, most notably as a repressor modulating the response to TGFbeta signalling. Human TGIF has been associated with the developmental disorder holoprosencephaly. Drosophila TGIF is represented by the products of two tandemly repeated highly similar genes, achintya and vismay. We have generated mutations that delete both genes. Homozygous mutant flies are viable and appear morphologically normal, but the males are completely sterile. The defect lies at the primary spermatocyte stage and differentiation is blocked prior to the onset of the meiotic divisions. We show that mutants lacking TGIF function fail to activate transcription of many genes required for sperm manufacture and of some genes required for entry into the meiotic divisions. This groups TGIF together with two other genes producing similar phenotypes, always early and cookie monster, as components of the machinery required for the activation of the spermatogenic programme of transcription. TGIF is the first sequence-specific transcription factor identified in this pathway. By immunolabelling in mouse testes we show that TGIF is expressed in the early stages of spermatogenesis consistent with a conserved role in the activation of the spermatogenesis transcription programme.

Characterization of histone H2A.X expression in testis and specific labeling of germ cells at the commitment stage of meiosis with histone H2A.X promoter-enhanced green fluorescent protein transgene.

To study the complex molecular mechanisms of mammalian spermatogenesis, it would be useful to be able to isolate cells at each stage of differentiation, especially at the stage in which the cells switch from mitosis to meiosis. Currently, no useful marker proteins or gene promoters specific to this important stage are known. We report here a transgenic mouse line that under the control of the promoter for a histone variant, H2A.X, expressed an enhanced green fluorescent protein (EGFP) in cells at the stage of the mitosis-meiosis switch. Endogenous H2A.X is expressed in type A spermatogonia through meiotic prophase spermatocytes in testis and in some somatic cells. However, despite the fact that its expression was driven by the H2A.X promoter, the EGFP expressed in the transgenic mice specifically labeled only the intermediate spermatogonia stage through the meiotic prophase spermatocyte stage in transgenic mice containing the -600-base pair H2A.X promoter/EGFP construct. Type A spermatogonia and somatic cells of other organs were not labeled. This expression pattern made it possible to isolate living cells from the testis of the transgenic mice at the stage of the mitosis-meiosis switch in spermatogenesis using EGFP fluorescence.

A stereological study of the effects of experimental inguinal cryptorchidism and subsequent orchiopexy on spermatogenesis in adult monkeys.

Our previous study demonstrated that experimental intra-abdominal cryptorchidism in adult rabbits for 13 weeks resulted in severe spermatogenic arrest: type A spermatogonia was the only germ cell type seen in the seminiferous epithelium and its number per testis was reduced by 84%. Seven weeks following orchiopexy, the type A spermatogonial number returned to the near-normal range in most animals and spermatogenesis partially recovered (Reproduction 2002, 124, 95-105). This study aimed to determine whether inguinal cryptorchidism would produce less-severe damage to spermatogenesis and whether subsequent orchiopexy would better restore spermatogenesis. Five normal adult male rhesus monkeys (Macaca mulatta) underwent bilateral artificial inguinal cryptorchidism. Half a year later, one testis together with the ipsilateral epididymis were removed from each animal and then unilateral orchiopexy was performed on the contralateral side, with the remaining testis and epididymis being removed another half a year later. A contemporary unbiased and efficient stereological tool, the optical disector, was used to estimate numbers of all types of spermatogenic cells in the testis and spermatozoa in the epididymis. Spermatogenic arrest was induced by cryptorchidism at the stage of spermatogonia (n = 1), spermatocytes (n = 2) or early spermatids (n = 1), with the type A spermatogonial numbers per testis being reduced to 14.8-57.2% of the control average; in one of the five cryptorchid animals, however, spermatogenesis remained normal. Subsequent orchiopexy, which was successfully performed on two animals with cryptorchidism-induced spermatogenic arrest, brought on a full or partial recovery of spermatogenesis. In conclusion, inguinal cryptorchidism induces less severe (in comparison with an intra-abdominal one) and variable damage to spermatogenesis, which is restored, at least in part, by subsequent orchiopexy.