The influence of vasovasostomy on testicular alterations after vasectomy in Lewis rats

The occurrence of alterations in testicular weight and morphology after vasectomy and vasectomy reversal by vasovasostomy was studied in Lewis rats. Animals were studied 3, 4, and 7 months after bilateral vasectomy or a vasectomy followed 3 months later by vasovasostomy. Other rats served as sham-operated controls. The weights of the testes in vasectomy and vasovasostomy animals fell into two groups-small testes weighing less than 0.88 g and normal-sized testes of 1.2 g or more. When the extent of testicular alterations was estimated in sections for light microscopy by use of a semiquantitative testicular biopsy score count (TBSC), the morphology of the testes corresponded closely to the testis weight (r = .94), small testes having correspondingly low TBSC scores. In severely altered small testes, the seminiferous tubules were narrower than in sham-operated rats, and numbers of germ cells were greatly depleted. Many tubules contained only Sertoli cells and spermatogonia, although spermatocytes were present in a minority of tubules. A few seminiferous tubules contained multinucleate spermatids. Electron microscopy of severely altered tubules revealed closely apposed processes of Sertoli cells, which contained filaments, microtubules, and endoplasmic reticulum. In contrast, testes with normal weight in vasectomy and vasovasostomy groups resembled those of the sham-operated animals. Comparison of distributions of testicular biopsy score counts demonstrated differences between vasectomy and vasovasostomy groups as time after operation increased. At the 3-4-month intervals, approximately one-third of the testes were severely altered in both vasectomy and vasovasostomy groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Morphological alterations and distribution of occludin in rat testes after bilateral vasectomy

The aim of study was to investigate the fate and the morphology of the cells which constitute the spermatogenic line, and to determine the distribution of occludin in the testis in adult vasectomized Wistar rats. The rats were divided into two groups: control group (sham-operated) and vasectomized group. One, 3 and 6 months after sham and vasectomy operations, testis samples were examined. The weight of the testes was found to be reduced 3 and 6 months after vasectomy. There was vacuolization in the seminiferous tubules one month after vasectomy. The tubules showed severe atrophy 3 and 6 months after vasectomy. The occludin immunolabeling in the 3- and 6-month groups was weak and diffuse, and the density of the protein was found to be decreased. The increase in the number of apoptotic cells was accompanied by a time-dependent decrease in the number of haploid, diploid and tetraploid cells. This study demonstrated that vasectomy causes degeneration in the seminiferous tubules with alterations in occludin distribution with a decrease in the number of spermatogenic cells. Moreover, these alterations increase in a time-dependent manner.     

Spermatogenesis in the vasectomized monkey: Quantitative analysis

The seminiferous epithelium in mature vasectomized Macaca fascicularis was examined quantitatively to assess spermatogenesis. Monkeys were bilaterally vasectomized and controls were bilaterally sham operated. At postoperative periods of 10 and 18 months, groups of monkeys were castrated and their testes prepared for morphologic analysis. Diameters were measured in 100 cross sections of seminiferous tubules from each animal. Numbers of spermatogonia (Ad and Ap), preleptotene spermatocytes, pachytene spermatocytes, and step 7 spermatids, relative to Sertoli cell nucleoli, were counted in stage VII tubules. Tubule diameter and germ cell numbers per Sertoli cell nucleoli were not altered by vasectomy. Our study demonstrates quantitatively that spermatogenesis in the monkey is not inhibited up to 18 months following vasectomy.     

Effect of vasectomy on the seminiferous tubule boundary zone in the Albino Swiss rat

The boundary zone of a seminiferous tubule consists of the basement membrane of the seminiferous epithelium, its myoid cells, and their basal laminae. This study examines the boundary zones of seminiferous tubules in healthy and degenerated testes following long-term, left-sided vasectomy in the rat and compares them to those of sham-operated controls and adult rats exposed in utero to the antiandrogen, flutamide. Degenerated tubular profiles showed similar changes, irrespective of whether the degeneration was ipsilateral or bilateral. In transverse tubular profiles, the basal laminae of the seminiferous epithelium and the myoid cells became more undulating, that of seminiferous epithelium showing complex folding. The collagen layer of the boundary zone, which lies between the basal laminae of the seminiferous epithelium and the myoid cells, thickened and its fibers became irregularly orientated. Rather than being flattened as in controls, the region of the myoid cell near the nucleus and the nucleus itself developed triangular profiles in the transversely sectioned tubules. Similar features were also seen in the degenerated tubules of rats exposed to flutamide. The changes in the boundary zone are not specific for vasectomy and probably reflect reduction in the cross-sectional area of tubular profiles and possibly in their length. We also noted occasional leukocytes infiltrating the boundary zone; they may have increased in number in those tubules that showed degeneration following vasectomy.     

Germ cell transfer into rat, bovine, monkey and human testes.

Germ cell transplantation is a potentially valuable technique offering oncological patients gonadal protection by reinitiating spermatogenesis from stem cells which were reinfused into the seminiferous tubules. In order to achieve an intratubular germ cell transfer, intratubular microinjection, efferent duct injections and rete testis injections were applied on dissected testes of four different species: rat, bull, monkey and man. Ultrasound-guided intratesticular rete testis injection was the best and least invasive injection technique with maximal infusion efficiency for larger testes. Deep infiltration of seminiferous tubules was only achieved in immature or partially regressed testes. This technique was applied in vivo on two cynomolgus monkeys. In the first monkey a deep infusion of injected cells and dye into the lumen of the seminiferous tubules was achieved. In the second, transplanted germ cells were present in the seminiferous epithelium 4 weeks after the transfer. These cells were morphologically identified as B-spermatogonia and located at the base of the seminiferous epithelium. In summary, this paper describes a promising approach for germ cell infusion into large testes. The application of this technique is the first successful attempt of a germ cell transfer in a primate.     

Degenerated tubules in the guinea pig testis after long-term vasectomy or sham operation

The testes of eight unilaterally vasectomized and six sham-operated Dunkin Hartley guinea pigs were examined 3 years after operation by wax and resin histology and transmission electron microscopy. Degenerated tubules are reported that were common on the side of vasectomy but also found in the contralateral testes and in the controls. A central accumulation of macrophages, rich in phagocytosed debris including spermatozoal fragments, was surrounded by attenuated Sertoli cells, a markedly thickened basement membrane and myoid cells. At some sites macrophages impinged directly on the basement membrane. They probably represented highly degenerated seminiferous tubules. The study suggests that the response to injury of seminiferous tubules may show species variations. Macrophages did not feature in the degenerated seminiferous tubules we reported following vasectomy in the rat. However, the rat showed striking changes in the morphology of the basal laminae and myoid cells which did not occur in the guinea pig. Pathological changes have been reported in the human testis following vasectomy but their etiology is unclear. Studies in the guinea pig are enhancing understanding of the mechanisms and features of testicular damage.     

Effect of long‐term vasectomy on seminiferous tubules in the guinea pig

The little previous work on the influence of vasectomy on the guinea pig testis has given controversial results. One group reports that the guinea pig suffers autoimmune orchitis while others claim damage may be mechanical. To clarify the issue, this study compares the morphology of seminiferous tubules 3 years after left unilateral vasectomy (8 guinea pigs) and control sham operation (6 animals). Grossly, left and right testes following left‐sided vasectomy were similar to controls and not significantly different in weight. On histology, left and right experimental testes and the control material showed various degrees of seminiferous tubular degeneration, including intraepithelial vesicle formation, loss of germ cells and intraluminal macrophages. Although vesicle formation was striking in most testes, quantitative analysis indicated that it was more frequent in the ipsilateral testis following unilateral vasectomy. It seems that vasectomy had exacerbated an age‐related phenomenon. Lymphocytic infiltration was seen in five of the left testes following vasectomy, in two of the corresponding right testes, but in none of the controls. Two vasectomized left testes, however, showed atrophic changes but no lymphocytic invasion. The results suggest that autoimmune orchitis follows vasectomy but that it may not be the primary cause of degeneration. Attempts to gain positive evidence for mechanical damage, however, were inconclusive. Clin. Anat. 12:250–263, 1999. © 1999 Wiley‐Liss, Inc.     

Histologic changes in the mouse testis after treatment with gossypol tetra-acetic acid

The effect of oral administrations (20 or 40 mg/kg body weight/day, for 21 days) of gossypol tetraacetic acid on the testis of the Parkes strain mouse was investigated. Gossypol treatment did not affect the body weight or testicular weight, but caused a significant depression in the weight of the seminal vesicle. Histologically, the testes in mice treated with gossypol possessed regressed seminiferous tubules showing the exfoliation of germ cells, the occurrence of giant cells, a disorganization of the germinal epithelium, the degeneration of germinal elements, intraepithelial vacuolation and dislocation of the Sertoli cells into the luminal portion. However, the effect of gossypol was not uniform, and normal features were also observed in the majority of the tubules in the testes of the gossypol-treated mice. When quantitatively analysed, the frequency of regressed seminiferous tubules was significantly higher in the testes in the treated mice than the controls. The results suggest that the gossypol treatment induces non-uniform regressive changes in the seminiferous tubules in the mouse testis.     

Focal orchitis in undescended testes: discussion of pathogenetic mechanisms of tubular atrophy.

OBJECTIVE: To evaluate seminiferous epithelium lesions in adult cryptorchid testes showing lymphoid infiltrates in seminiferous tubules and interstitium (i.e., focal orchitis). Also, to consider the possible role of this lesion in the etiology of tubular atrophy. METHODS: We performed a histopathologic study of the cryptorchid testes and adjacent epididymides removed from 50 adult men who had not been previously treated for cryptorchidism. The study included morphologic and semiquantitative evaluation of seminiferous tubule pathology (according to germ cell numbers), Sertoli cell morphology, tubular lumen dilation, rete testis pattern (normal, hypoplastic, or cystic), and epididymal pattern (normal or epididymal duct hypoplasia). The study also included immunohistochemical evaluation of immune cell markers. The results were compared with clinical and laboratory findings. RESULTS: Focal lymphoid infiltrates (mainly lymphocytes) in seminiferous tubules and interstitium were found in 22 patients (44%), all of whom had unilateral cryptorchidism. The course of orchitis was asymptomatic, and laboratory data were normal. According to the seminiferous tubule pathology, a variety of histopathologic diagnoses, were made: (1) mixed atrophy consisting of Sertoli cell-only tubules intermingled with tubules showing maturation arrest of spermatogonia (11 testes, 4 of which also showed hyalinized tubules); (2) Sertoli cell-only tubules plus hyalinized tubules (4 testes); (3) Sertoli cell-only tubules (3 testes); (4) intratubular germ cell neoplasia (2 testes, 1 of which also showed hyalinized tubules); (5) complete tubular hyalinization (1 testis); and (6) tubular hyalinization plus some groups of tubules with hypospermatogenesis (all germ cell types were present although in lower numbers, 1 testis). Dysgenetic Sertoli cells, that is, Sertoli cells that had undergone anomalous, incomplete maturation, were observed in all nonhyalinized seminiferous tubules with inflammatory infiltrates. Tubular ectasia was observed in 13 cases. The rete testis was hypoplastic and showed cystic transformation in 18 testes, and the epididymis was hypoplastic in 15 testes. CONCLUSIONS: The causes of these focal inflammatory infiltrates are unknown. It is possible that tubular ectasia and Sertoli cell dysgenesis are involved and that these alterations cause a disruption of the blood-testis barrier and allow antigens to enter the testicular interstitium, giving rise to an autoimmune process.     

Proliferation and apoptosis of spermatogonia in postpuberal boar (Sus domesticus) testes with spontaneous unilateral and bilateral abdominal cryptorchidism

Cryptorchidism is a frequent male sexual disorder in mammals, which affects the histology of the tunica propria, interstitial tissue, blood vessels, seminiferous epithelium and testis functioning. In this paper, proliferation and apoptosis were examined in the seminiferous epithelium of both testes from unaffected boars and from boars suffering unilateral and bilateral cryptorchidism. In germ cells, proliferation was studied using the immunohistochemical PCNA technique, and apoptosis was analysed by in situ TUNEL labelling. An index was obtained for the proliferation and apoptosis observed in seminiferous tubules. In abdominal testes the epithelium contained few spermatogonia and Sertoli cells. In the testes of unaffected boars, numerous spermatogonia proliferated, whereas in cryptorchid testes such proliferation was lower and the proliferation/apoptosis ratio diminished. In the unaffected group, the TUNEL-positive germ cells were spermatogonia and spermatocytes in different phases of meiosis. In abdominal testes, the TUNEL-positive germ cells were spermatogonia alone. The apoptosis index of both abdominal and scrotal testes was similar. In conclusion, spontaneous cryptorchid testes showed a lower rate of spermatogonia proliferation in the seminiferous epithelium.     

The organization of the seminiferous epithelium in the mouse testis following ligation of the efferent ductules. A light microscopic study

In order to more fully assess and determine the relationship between the developing germ cells and the Sertoli cell epithelium, efferent ductules of Swiss albino mice testes were ligated and the effects observed. This method stretched the walls of the seminiferous tubules and thus reduced the stratification and complexity of the epithelium. At 48 hours postoperation, the testes were removed in a manner to prevent the escape of accumulated fluid. A marked size difference between the ligated and sham-operated testes was noted. Tissues were fixed in 3% phosphate buffered glutaraldehyde solution and later prepared for sectioning and examination by the light microscope. The seminiferous tubules in the ligated testes had relatively large lumens which contained spermatozoa, and the tubule epithelium was reduced in height. The various stages of cellular associations of the cycle of the epithelium were retained. Defined aggregations of germ cells grouped in specific association with the Sertoli cell elements were observed. The epithelium assumed the form of a series of parallel ridges at right angles to the tubules. Longitudinal sections of the tubules revealed pillarlike epithelial profiles. Each pillar consisted of Sertoli cell cytoplasm together with 2 generations of spermatids. The older generation of spermatids was embedded within the Sertoli cell and the younger generation along the sides. It is suggested that each generation within a ridge constitutes a single clone. The cytoplasmic bridges joining the spermatids and their attachments to the Sertoli cells are thought to determine the organization and structure of the rid ges. Several illustrations show the histological details of the structure.     

Changes in seminiferous tubules after vasectomy

The histologic, immunohistochemical, and ultrastructural changes in the seminiferous tubules (ST) of 17 healthy adult males who had been vasectomized between 1 1/2 and 5 years are reported. There was minimal spermatogenesis in 4 cases. 8 of the cases underwent electron microscopy examination and 4 showed evidence of minimal histological spermatogenesis. The ST showed a thickening of the basement membrane and heavy deposits of lipofuchsin in the Sertoli cells (SC) seen as lipid infiltration. The spermatogenic cells presented variable changes characterized by the disorientation of cells, maturation arrest, and premature sloughing. No immune complex deposits were seen. Of the 9 cases followed, pregnancy occurred in 2 following vas reanastomosis; a regenerative capacity of the ST was seen in 6 cases. The follow-up studies also show that the morphological alterations initially produced by the vasectomy have little affect on the appearance of spermatogenesis after vas reanastomosis. Thus, we see that the vasectomy exerts its major effect on the SC and that the damage to these cells alters the testicular environment. However, these changes are apparently reversible following vasovasostomy.     

Macro-orchidism: light and electron microscopic study of four cases.

A hormonal and quantitative light microscopy study of one man with macro-orchidism associated with mental retardation and fragile X chromosome (case no. 1) and three men with idiopathic macro-orchidism (cases no. 2 to 4) is reported. Hormonal study revealed slightly increased follicle-stimulating hormone serum levels in cases no. 1 to 3. The testes from cases no. 1 (orchidoepididymoectomy specimen) and 2 (testicular biopsy) presented interstitial edema and three different tubular patterns that were arranged in a mosaic-like manner. Type I tubules had an increased diameter (less than 220 microns), dilated lumen, and thin seminiferous epithelium usually consisting of Sertoli cells, spermatogonia, primary spermatocytes, and sometimes a few spermatids. Type II tubules had a normal diameter (180 to 220 microns) and germ cell development varied between complete spermatogenesis and Sertoli-cell-only tubules. Type III tubules had decreased diameter (less than 180 microns), atrophic seminiferous epithelium, and thickened tunica propria. The appearance of the nuclei of the Sertoli cells in the three types of tubules could be either mature or immature. Some of the mature Sertoli cells presented a granular cytoplasm. A few of these granular cells grouped together, forming nests that protruded into the tubular lumen. The testicular biopsies from cases no. 3 and 4 only presented type II tubules that contained both mature and immature Sertoli cells. Quantitative study revealed that the large testicular size was principally due to an increased tubular length in all four cases. Although the seminiferous tubule lesions and interstitial edema suggest an obstructive process, the testicular excretory ducts (studied in case no. 1) appeared normal or only slightly dilated. It is possible that the seminiferous tubule lesions (dilated lumen and germ cell depletion) might be secondary to the Sertoli cell lesions (granular cytoplasm and nuclear immature-like pattern.     

Fine structure of boundary tissue of the seminiferous tubules in the scrotal and abdominal testes of naturally unilateral cryptorchid West African dwarf goats

The boundary tissue of the seminiferous tubules in the scrotal and abdominal testes of naturally unilateral cryptorchid West African dwarf goats comprised an inner non-cellular, a middle cellular and peripheral cellular lamellae. In the scrotal testes, these components were compact and their arrangement conformed to that described for other domestic ruminants except that here, the basal lamina associated with the seminiferous epithelium was homogeneous and in tact. Alterations due to cryptorchidism as observed in the contralateral abdominal testes include general loss of compactness due to depletion and disorganization of structural extracellular materials like basal lamina coat of myoid cells and collagen fibrils, the splitting of the basal lamina of the seminiferous epithelium into 8-12 thin layers, poor differentiation of the myoid cells and the accumulation of lipid droplets within their cytoplasm. It is concluded that the normal caprine boundary tissue conforms entirely to the characteristics of 'Type C' category in the existing classification. The ultrastructural alterations due to abdominal retention of the testis resemble the testicular changes ascribed to the disturbance of pituitary-testicular hormonal axis.     

Vimentin expression during altered spermatogenesis in rats

The collapse of vimentin caused by some xenobiotics correlates with the loss of structural integrity of the seminiferous epithelium. In this study, we investigated the effect of busulphan (an anticancer drug with toxic effects on dividing germ cells) on vimentin filament distribution in rat seminiferous epithelium and compared it with changes found in testes of unilaterally cryptorchid rats. In the seminiferous epithelium, the vimentin labelling was observed only in the Sertoli cells, showing a stage-specific arrangement of the filaments. Both busulphan treatment and cryptorchism caused altered distribution of vimentin filaments in the Sertoli cells. In both models, the apical vimentin filaments collapsed towards the nuclei and were disorganized in the basal region of the Sertoli cells while the germ cells were diminished in the epithelium. After the busulphan effect subsided (4 weeks after administration), spermatogenesis began to restore and vimentin filaments began to organize in basal and perinuclear regions of Sertoli cells among the spermatogonia and spermatocytes. Vimentin labelling of the sloughed material in the lumen of cryptorchid testes (but not in busulphan treated animals) was observed. We conclude that the Sertoli cell vimentin filaments play an important role in the maintenance of spermatogenesis, their damage is associated with the seminiferous epithelium disintegration and their restoration with a recovery of spermatogenesis after the unfavourable conditions subside.     

Immunological and morphological effects of vasectomy in the rabbit

Half of the rabbits developed antisperm antibodies (measured by either indirect immunofluorescence or sperm immobilization tests) after either a unilateral or bilateral vasectomy. The raised antibody levels, particularly six months or longer after vasectomy, often accompanied patchy orchitis. Seminiferous tubules from such animals exhibited sloughed, multinucleated, and immature germinal cells which were engulfed by phagocytic cells. Mononuclear infiltrates were occasionally present. The basal lamina infolded and thickened by means of supernumerary layers and appeared to be endocytosed by cells of the seminiferous tubules. Four months after vasectomy, numerous phagocytic cells were seen to migrate through the intact epithelium of zone 1 in the caput epididymidis, and were particularly prevalent in animals that exhibited testicular damage. These macrophages may serve to present sperm antigens to lymphocytes.     

Androgen aromatization in cryptorchid mouse testis

Estrogens play an important role in germ cell development. Therefore, we have studied expression patterns of aromatase that converts testosterone into estrogens in 2 recombinant inbred mouse strains that differ in efficiency of spermatogenesis. In order to show whether germ cells are a target for estrogens, estrogen receptors (ER)alpha and beta were localized as well. Adult male CBA and KE mice were made unilaterally cryptorchid to determine alterations in testicular steroidogenesis and spermatogenesis. Differences between control and cryptorchid testes have been studied with respect to (1) cellular sites of aromatase, the enzyme responsible for estrogen formation, (2) the presence of ERalpha and ERbeta in various types of testicular cells, and (3) steroidogenic activity in the testes. Additionally, unilaterally control testes of cryptorchid mice were compared with bilaterally descended testes. Histological or hormonal differences were not found between control testes of cryptorchid and untreated mice. In cryptorchid testes from both strains, degeneration of germ cells was observed as well as a decrease in size of the seminiferous tubules, whereas the amount of interstitial tissue increased, especially in testes of CBA mice. Using immunohistochemistry, aromatase was localized in Leydig cells and germ cells in both control and cryptorchid testes. Sertoli cells were immunopositive in control testes only. In cryptorchid testes of KE mice, aromatase was strongly expressed in spermatids, that were still present in a few tubules. Other cell types in tubules were negative for aromatase. In both control and cryptorchid testes of both mouse strains, ERalpha were present in Leydig cells only, whereas ERbeta were found in Leydig cells and in germ cells in early stages of maturation. In homogenates of testes of CBA control mice, testosterone levels were 3-fold higher than in those of control KE mice, whereas the difference in estradiol levels between both strains was small. Cryptorchidism resulted in decreased testosterone levels and increased estradiol levels. The results of the present study show functional alterations due to cryptorchidism in both mouse strains. Strong aromatase expression in germ cells in control and cryptorchid testes indicates an additional source of estrogens in the testis besides the interstitial tissue and the relevance of estrogen in spermatogenesis.     

Testicular dysfunction induced by penconazole fungicide on male albino rats

In the present study, penconazole fungicide was examined for its affect on the morphology and function of testes in rats. Male rats were orally administered penconazole at a dose of 50 or 100 mg/kg, three times/week, for 9 months. Testosterone hormone level was measured using enzyme-linked immunosorbent assay (ELISA). Testicles were submitted for histopathological examination using light microscope. Testicles were exposed for more investigation using transmission electron microscope. Quantitative analysis of seminiferous epithelial cycle and Leydig cells were obtained. The results revealed that a significant decrease in testosterone hormone level than the control group. Light microscope examination showed necrotic and degenerative changes in testes at the level of seminiferous tubules. Sertoli, Leydig, and germ cell numbers showed significant depletion. Ultrastructural investigation showed Sertoli and Leydig cells had several morphological alterations. Spermatogonic cells showed multiple features of apoptosis. From the previous findings, we concluded that penconazole fungicide induced structural and functional testicular impairment. The use of penconazole as a fungicide must be restricted and regularly monitored in the environment.     

Antispermatogenic activity of 1-p. chlorobenzyl-1H indazol-3-carboxylic acid (AF 1312/TS) in rats. III. A light and electron microscopic study after single oral doses.

The modifications of the seminiferous epithelium at short time intervals after the administration of a single dose of 1-p. chlorobenzyl-1H-indazol-3-carboxylic acid, AF $\text{1312}\text{TS}$, have been sequentially studied in prepuberal and adult rats. $\text{AF 1312}\text{TS}$ is a new chemical compound with a selective antispermatogenic activity. Alterations of the seminiferous epithelium are observable within 24 hours after drug administration. The germ cells affected are primary and secondary spermatocytes and spermatids at various stages of their differentiation. Numerous nuclear and cytoplasmic aspects of the damage are illustrated. Early cytoplasmic and nuclear alterations are also observable in the Sertoli cells. The lesions of the germinal epithelium increase gradually and 5 days after the treatment numerous tubules show a conspicuous reduction of the germ cell number. Spermatogonia do not display cytologic alterations. The possibility is discussed that the Sertoli cells play a key role in the antispermatogenic action of $\text{AF 1312}\text{TS}$.     

Distinct changes in the laminin composition of basement membranes in human seminiferous tubules during development and degeneration.

We studied the distribution of laminin (Ln) chains and their integrin (Int) receptors in normal developing and adult and in atrophied human testes by using immunohistochemistry. Immunostaining for EHS Ln and type IV collagen was used to identify basement membranes (BMs). In the BM of seminiferous epithelium of fetal testis, a panel of monoclonal antibodies showed immunoreactivity for Ln alpha 1-, alpha 2-, beta 1-, beta 2- and gamma 1-chains, suggestive of the presence of Lns 1 to 3. In BM of adult seminiferous epithelium with active spermatogenesis, immunoreactivity for Ln beta 2- and gamma 1-chains was found but not for Ln alpha-chains, suggesting a complex of Ln chains not compatible with any known trimers. Instead, with polyclonal Ln antiserum and monoclonal antibody to type IV collagen, a distinct BM-like reactivity was seen. In atrophied testes, prominent immunoreactivities for Ln chains, compatible with Lns 1 to 3, were seen in the thickened BM of seminiferous tubules, hence suggestive of reappearance of fetal Lns. Among the subunits of Ln-binding Int receptors in fetal seminiferous tubules, a strong immunoreactivity for Int beta 1- and Int alpha 6-subunits was seen throughout the seminiferous epithelium, other Int subunits being found in interstitial cells. In the adult and atrophied testes, immunoreactivities for Int beta 1- and Int alpha 6-subunits were seen to be confined to the basal aspect of the seminiferous epithelium whereas immunoreactivities for Int alpha 1-, alpha 2-, alpha 3- and beta 4-subunits were seen in the myoid cells. The results show that both maturation and degenerative changes of human testes are accompanied by distinct changes in the Ln expression of BM of seminiferous epithelium, which appears to accompany epithelial differentiation of the Sertoli cells. Furthermore, they suggest the presence of a novel Ln trimer in BM of adult human seminiferous tubules.