Lectin histochemistry of the human testis

Sialylation status and its relationship with morphofunctional changes in human adult testis during sexually mature life and aging: A narrative review

Sialic acids (Sias) are a family of electronegatively charged nine-carbon monosaccharides containing a carboxylic acid, mostly found as terminal residues in glycans of glycoproteins and glycolipids. They are bound to galactose or N-acetylgalactosamine via α2,3 or α2,6 linkage, or to other Sias especially via α2,8 linkage, which results in monomeric, oligomeric, and polymeric forms. Sias play determinant roles in a multitude of biological processes in human tissues from development to adult life until aging. In this review, we summarized the current knowledge on the sialylation status in the human testis with a main focus on sexually mature life and aging, when this organ shows significant morphofunctional changes resulting into variations of hormonal levels, as well as changes in molecules involved in mitochondrial function, receptors, and signaling proteins. Evidence suggests that Sias may have crucial morphofunctional roles in the different testicular components during the sexually mature age. With advancing age, significant loss of Sias and/or changes in sialylation status occur in all the testicular components, which seems to contribute to morphofunctional changes characteristic of the aging testis. Based on the current knowledge, further in-depth investigations will be necessary to better understand the mechanistic role of Sias in the biological processes of human testicular tissue and the significance of their changes during the aging process. Future investigations might also contribute to the development of novel prophylactic and/or therapeutic approaches that, by maintaining/restoring the correct sialylation status, could help in slowing down the testis aging process, thus preserving the testicular structure and functionality and preventing age-related pathologies.

Differential cellular localization of lectins in the testes of dromedary camel (Camelus dromedarius) during active and inactive breeding seasons

The reproductive activity of the male dromedary camel (Camelus dromedarius) as a seasonal breeder is affected by various seasonal changes that reflect on the reproductive performance. In the current study, we explored a differential cellular localization of lectins in eight dromedary camel testes utilizing lectin histochemistry (LHC). The glycoconjugates' localizations were detected within the testicular tissue utilizing 13 biotin-labeled lectins (PNA, ConA, LCA, RCA120, GS IB4, WGA, BPL, DBA, ECA, PHA-E4, UEA-1, PTL-II, and SBA) distributed into six sets. The cellular structures revealed diverse lectins distribution that may reflect various glycoproteins' structures and their compositional modifications during spermatogenesis. Some of the investigated lectins were restricted to acrosomes of spermatids that will help study different stages during the spermatogenic cycle of dromedary camel, particularly PNA, and ECA. The statistical analysis showed a marked positive correlation between the response intensity of various lectins and the breeding season (P < 0.05). We can conclude that lectins have a fundamental role during camel spermatogenesis and are associated with the reproductive activity of dromedary camel.

Comparative Cellular Localization of Sugar Residues in Bull (Bos taurus) and Donkey (Equus asinus) Testes Using Lectin Histochemistry

Lectins are glycoproteins of a non-immune origin often used as histochemical reagents to study the distribution of glycoconjugates in different types of tissues. In this study, we performed a comparative cellular localization of sugar residues in bull and donkey testes using immunofluorescent lectin histochemistry. We inspected the cellular localization of the glycoconjugates within the testes using 11 biotin-labeled lectins (LCA, ConA, PNA, WGA, DBA, SBA, ECA, BPL, PTL-II, UEA-1, and PHA-E4) classified under six groups. Although the basic testicular structure in both species was similar, the cellular components showed different lectin localization patterns. The statistical analysis revealed no significant association between the intensity of labeling and different variables, including group and type of lectin and type of cell examined, at p < 0.05. However, a stronger response tended to occur in the donkey than in the bull testes (odds ratio: 1.3). These findings may be associated with the different cellular compositions of the glycoproteins and modification changes during spermatogenesis. Moreover, glycoconjugate profiling through lectin histochemistry can characterize some cell-type selective markers that will be helpful in studying bull and donkey spermatogenesis.

The Distribution Profile of Glycoconjugates in the Testis of Brown-Banded Bamboo Shark (Chiloscyllium punctatum) by Using Lectin Histochemistry

The testis of bamboo shark is characterized by diametric development leading to zonation architecture. Here, we investigated the staining pattern of 12 lectins in 6 groups of differential binding specificities within the germ, somatic, and interstitial cells of each zone. The neutral mucopolysaccharides appeared in the interstitial tissue in all the zones and became more significant in the spermatozoal–Sertoli cell junction. The cellular localization of the lectins varies in testicular zones and cell types. There was a gradual increase in glycosylation toward the degenerative zone. The increased intensity of most lectins in the interstitial cells indicates the association of glycoconjugates in their androgen-secreting activity. Statistical analyses showed a significant correlation between the groups of lectins and each lectin used, stronger response to lectins in the interstitial cells (ICs) than other cell types. Moreover, the response to glucosamine (GlcNAc), galactosamine (GalNAc), and fucose tended to be higher than glucose and galactose. Furthermore, the intensity of response was increased toward the degenerative zone. In addition, we can use peanut agglutinin (PNA) as an acrosomal marker in combination with other marker proteins for studying shark spermatogenesis. These findings refer to the crucial role of glycoconjugates in spermatogenesis in the bamboo shark testis.

Symbiont Transmission onto the Cell Surface of Early Oocytes in the Deep-Sea Clam Phreagena okutanii

Symbiotic associations with beneficial microorganisms endow a variety of host animals with adaptability to the environment. Stable transmission of symbionts across host generations is a key event in the maintenance of symbiotic associations through evolutionary time. However, our understanding of the mechanisms of symbiont transmission remains fragmentary. The deep-sea clam Phreagena okutanii harbors chemoautotrophic intracellular symbiotic bacteria in gill epithelial cells, and depends on these symbionts for nutrition. In this study, we focused on the association of these maternally transmitted symbionts with ovarian germ cells in juvenile female clams. First, we established a sex identification method for small P. okutanii individuals, and morphologically classified female germ cells observed in the ovary. Then, we investigated the association of the endosymbiotic bacteria with germ cells. We found that the symbionts were localized on the outer surface of the cell membrane of primary oocytes and not within the cluster of oogonia. Based on our findings, we discuss the processes and mechanisms of symbiont vertical transmission in P. okutanii.

Lectin-binding pattern of glycoconjugates during spontaneous testicular recrudescence in Syrian hamster (Mesocricetus auratus) after exposure to short photoperiod

Lectin histochemistry was used to characterise glycoconjugates and cellular apoptosis in the seminiferous epithelium and interstitium of hamster testis during spontaneous recrudescence. An increase in the LTA lectin affinity was observed in spermatids in the Golgi phase. An increase in labelling of PNA and Con-A lectin in acrosome of spermatids (acrosome phase) as well as increased labelling with Con-A in spermatids (cap phase) was observed. Spermatocytes showed decreased affinity with PNA and AAA lectins and an increase in positivity for LTA and GNA lectins. Spermatogonia showed a slight decrease in positivity to WGA and an increase in labelling with Con-A and a decreased affinity for the AAA lectin. At the end of recrudescence, all these germinal cells showed a similar pattern to the control. The Sertoli cells showed a gradual decrease in labelling with the GNA lectin and the Leydig cells an increase in labelling with Con-A and GNA. Particularly unusual was the observation of apoptotic spermatocytes and spermatids positive for PNA, GNA, AAA and Con-A, together with spermatocytes positive to LTA. In conclusion, the normal lectin pattern is recovered during testis recrudescence and germ cell apoptotic activity is low, as is observed by specific lectins for germ cells in apoptosis.

Distribution of lectin-bindings in the testis of the lesser mouse deer, Tragulus javanicus

The distribution of lectin bindings in the testis of the smallest ruminant, lesser mouse deer (Tragulus javanicus), was studied using 12 biotinylated lectins specific for d-galactose (peanut agglutinin PNA, Ricinus communis agglutinin RCA I), N-acetyl-d-galactosamine (Dolichos biflorus agglutinin DBA, Vicia villosa agglutinin VVA, Soybean agglutinin SBA), N-acetyl-D-glucosamine and sialic acid (wheat germ agglutinin WGA, s-WGA), D-mannose and d-glucose (Lens culinaris agglutinin LCA, Pisum sativum agglutinin PSA, Concanavalin A Con A), L-fucose (Ulex europaeus agglutinin UEA I), and oligosaccharide (Phaseolus vulgaris agglutinin PHA-E) sugar residues. In Golgi-, cap-, and acrosome-phase spermatids, lectin-bindings were found in the acrosome (PNA, RCA I, VVA, SBA, WGA and s-WGA), and in the cytoplasm (PNA, RCA I, VVA, SBA, WGA, LCA, PSA, Con A and PHA-E). s-WGA binding was confined to the spermatid acrosome, but other lectins were also observed in spermatocytes. In spermatogonia, VVA, WGA, Con A, and PHA-E bindings were observed. Sertoli cells were intensely stained with DBA and Con A, and weakly with PHA-E. In interstitial Leydig cells, RCA I, DBA, VVA, Con A, PSA, LCA, WGA and PHA-E were positive. UEA I was negative in all cell types including spermatogenic cells. Unusual distribution of lectin-bindings noted in the testis of lesser mouse deer included the limited distribution of s-WGA only in the spermatid acrosome, the distribution of DBA in Sertoli cells, Leydig cells and lamina propria, and the absence of UEA I in all type cells. The present results were discussed in comparison with those of other animals and their possible functional implications.

Sialic acid in human testis and changes with aging

The aim of the present study was to investigate the distribution of the glycoconjugates sialoderivatives in the human testis. Orchidectomy specimens from men aged 18–30 years (Group 1) and from men aged 70–93 years (Group 2) were obtained at autopsy. The study was performed using digoxigenin-labelled lectins, namely Maackia amurensis II lectin (MAA), Sambucus nigra agglutinin (SNA) and Arachis hypogaea lectin (PNA), in addition to enzymatic and chemical treatments (neuraminidase, KOH–neuraminidase, mild oxidation–neuraminidase, mild oxidation–KOH–neuraminidase, strong oxidation–neuraminidase, strong oxidation–KOH–neuraminidase), to characterise the different glycosidic linkages of the sialoderivatives and to obtain information regarding their structure. In all Group 2 samples, sialic acids linked α-2,3 to galactose and α-2,6 to galactose/N-acetyl-d-galactosamine (Gal/GalNAc), revealed by MAA and SNA, respectively, were observed in testicular interstitial tissue and in the lamina propria. Sialic acid linked α-2,6 to Gal/GalNAc was detected in only some samples from Group 1. After treatment, PNA showed structural changes and/or the gradual disappearance of sialic acid linked to d-galactose-β(1–3)-N-acetyl-d-galactosamine in testicular components with aging. These findings indicate that changes in the metabolism of sialoderivatives in the testis could be related to morphofunctional changes in various testicular components typical of this organ during aging. This suggests that sialoderivatives are important in the functionality of the mature testis in men, as well as its involution.

Histochemical mapping of glycoconjugates in the testis of the one humped camel (Camelus dromedarius) during rutting and non-rutting seasons

In the present study, the distribution of various sugar residues in the testicular cells of sexually mature camels during rutting and non-rutting seasons was examined employing 10 fluorescein isothiocyanate- (FITC) conjugated lectins. Lectin labeling was restricted to the germ cell lines and interstitial Leydig cells, while the Sertoli cells remained completely unlabeled. Our results revealed the presence of mannose (labeled by lectins PSA, LCA), galactose (labeled by PNA), GalNAc (labeled by HPA), and GlcNAc (labeled by WGA) residues in the camel spermatogonia. However, spermatocytes were only labeled with mannose (PSA, LCA) and GlcNAc (WGA) binding lectins. Binding sites for PSA, LCA and WGA in spermatogonia and spermatocytes were only evident during the rutting season. Although spermatids were exclusively labeled with PNA in the non-rutting seasons, other lectins (PSA, GSA-I, WGA) additionally bound to camel spermatids during the rutting period. Leydig cells and basal lamina of the seminiferous tubules of camel testis were consistently labeled with the mannose- (PSA, LCA) and GlcNAc- (WGA) binding lectins in both seasons, while DBA-labeling was seen in the Leydig cells during rutting period only. In conclusion, the findings of the present study clearly indicate that the camel testis contains a wide range of glycoconjugates (bearing mannosyl, galactosyl and glucosyl residues), and they lack fucosyl residues, both in the active sexual period and in the non-breeding season. The topographical distribution of the sugar moieties in the camel testis may indicate that specific carbohydrate structures are required for spermatogenesis during periods of sexual activity.

A Lectin Histochemical Study on the Testis of the Babirusa, Babyroussa babyrussa (Suidae)

The distribution of lectin bindings in the testis of babirusa, Babyrousa babyrussa (Suidae) was studied histochemically using 10 biotinylated lectins, Peanut agglutinin (PNA), Ricinus communis agglutinin (RCA I), Dolichos biflorus agglutinin (DBA), Vicia villosa agglutinin (VVA), Soybean agglutinin (SBA), Wheat germ agglutinin (WGA), Lens culinaris agglutinin (LCA), Pisum sativum agglutinin (PSA), Concanavalin A(Con A) and Ulex europaeus agglutinin (UEA I). Nine of 10 lectins showed a variety of staining patterns in the seminiferous epithelium and interstitial cells. The acrosome of Golgi-, cap- and acrosome-phase spermatids displayed various PNA, RCA I, VVA, SBA and WGA bindings, indicating the presence of glycoconjugates with D-galactose, N-acetyl-D-galactosamine and N-acetyl-D-glucosamine sugar residues respectively. No affinity was detected in the acrosome of late spermatids. LCA, PSA and Con A which have affinity for D-mannose and D-glucose sugar residues were positive in the cytoplasm of spermatids and spermatocytes. DBA was positive only in spermatogonia. In addition to DBA, positive binding in spermatogonia was found for VVA, WGA and Con A, suggesting the distribution of glycoconjugates with N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, D-mannose and D-glucose sugar residues. Sertoli cells were stained intensely with RCA I, WGA and Con A. In Leydig cells, RCA I and Con A were strongly positive, while WGA, LCA and PSA reactions were weak to moderate. The present findings showed that the distribution pattern of lectin binding in the testis of babirusa is somewhat different from that of pig or other mammals reported previously.

Morphological and histochemical characterization of the seminiferous epithelial and Leydig cells of the turkey

Unlike mammals, there is little fundamental information about spermatogenesis in birds. This study was undertaken to clarify the morphology, histochemistry, and lectin affinity of the seminiferous epithelial cells and Leydig cells in pre-pubertal (8- to 15-week old) and adult (40- to 44-week old) domestic turkeys. In adult turkeys, three types of spermatogonia were defined based on their chromatin distribution and nuclear morphology: the dark type A (A(d)); the pale type A (A(p)); and the type B. The A(d) is the least numerous and least conspicuous and consequently difficult to locate. Based on its spatial distribution and overall morphology, type A(d) spermatogonia were postulated to be the spermatogonia stem cells in the turkey. Antibodies to c-kit were localized to spermatogonia in the pre-pubertal and to a lesser extent in adult males. Peanut agglutinin (PNA) was specific for spermatocytes in the pre-pubertal males and spermatogonia and early spermatocytes in adult males. Wheat-germ agglutinin (WGA) highlighted Sertoli cells in both age groups. Bandeiraea simplicifolia I, soybean agglutinin, and winged-pea agglutinin staining were limited to the wall of the seminiferous tubule and some extra-tubular cell types. Concanavalin A staining was diffuse and not cell-specific and, therefore, could not be used to selectively identify a particular cell type. It was concluded that WGA and PNA could aid in identifying specific cell types in the seminiferous epithelium of testis from pre-pubertal and mature turkeys. Only Leydig cells were alkaline phosphatase reactive in the mature turkey testes. The information from this study is being used to adapt techniques for the isolation and partial purification developed for mammalian spermatogonia to avian spermatogonia and other specific cell types in the testes.

Examination of basement membrane components associated with the bovine seminiferous tubule basal lamina

Immunohistology has been used to examine the distribution of certain components of the basement membrane (BM) associated with bovine spermatogonial germ cells that are located within the seminiferous tubules. Histology was performed on testis tissue from Brahman cattle (Bos indicus) of three different age groups: pre-pubescent (4–6 months), juvenile (8–10 months) and adult (18–24 months) animals. There were no major changes in the BM composition apparent between these three age groups, except for certain lectin staining. These data suggest that the predominant collagen type IV component may have an α3 and α4 composition, although other chains, including the α5 and α6 chains, were also present. Possibly the main laminin type present was laminin 121 (α1β2γ1), although other variants were also present. Both nidogen-1 and perlecan, which are normal BM components, were also found as part of the seminiferous tubule BM. Interstitial collagens, such as type I, III and VI collagens, were found in the peritubular space, but were not part of the BM itself, although type VI collagen was most visible in the peritubular zone adjacent to the tubules. Examination of the BM with a range of lectins gave strong staining for (glcNAc)2 entities, weak positive staining for α-l-fuc, but little or no staining for α-galNAc and (glcNAc)3 at all ages, whereas staining for α-gal, β-gal(1→3)galNAc and α-man showed developmental changes.

Glycoconjugates of the urodele amphibian testis shown by lectin cytochemical methods

Lectin histochemistry is a useful method that allows the in situ identification of the terminal sugar moieties of the carbohydrates that form the glycoconjugates. Moreover, when it is combined with chemical or enzymatic deglycosylation pretreatments, lectin histochemistry can be employed to determine if carbohydrates are linked to the protein core by means of an N- or O-glycosidic linkage or, indeed, to partially sequence the sugar chains. One of the most interesting model organs for the study of spermatogenesis is the amphibian urodele testis. However, this organ has not been very widely investigated with lectin histochemical research. In the last few years, we have carried out a research project to identify and locate glycoconjugates in the testis of the urodele Pleurodeles waltl, the Spanish newt, as a first approach to identify possible carbohydrates with key roles in spermatogenesis. Our findings reveal some glycan chains located in a fusome-like structure in early (diploid) germ cells, oligosaccharides with terminal GalNAc in the acrosome, the occurrence of glycan modifications in the acrosomal contents during spermiogenesis, and changes in glycan composition of follicle and interstitial cells during the spermatogenetic cycle. Furthermore, the similar labeling pattern of follicle and duct cells supports the hypothesis for a common origin of both cell types.

Methods for in situ detection and characterization of extracellular polymers in biofilms by electron microscopy

Electron microscopy of biofilms and the localization of extracellular polymers at high resolution require the adaptation of conventional electron microscopic preparation and imaging techniques. A method developed for in situ fixation and embedding of biofilms, imaging of unstained thick sections with electron spectroscopic imaging and the application of lectin or antibody-based marker systems allowed interpretation of extracellular polymer distribution at micrometer scale. By this way, it is possible to discriminate in situ between extracellular polymers produced by different organisms.

The role of N-glycans in spermatogenesis

Many proteins, in particular those in the plasma membranes, are glycosylated with carbohydrates, which are grouped into O-glycans and N-glycans. O-glycans are synthesized step by step by glycosyltransferases, whereas N-glycans are synthesized by en-bloc transfer of the so-called high-mannose-type oligosaccharide from lipid-linked precursor to polypeptide. The high-mannose-type N-glycans are then modified by processing alpha-mannosidases. Alpha-mannosidase IIx (MX) was identified as the gene product of processing alpha-mannosidase II (MII)-related gene. MX apparently plays subsidiary role for MII in many cell types, as N-glycan patterns of MX null mouse tissues are not altered significantly. Surprisingly MX null male mice are infertile due to a failure of spermatogenesis. This review provides a brief overview of the in vivo role of N-glycans which are revealed by the gene knockout mouse approach, and introduce our studies on the MX gene knockout mouse. The MX gene knockout experiments unveiled a novel function of a specific N-glycan, which is N-acetylglucosamine-terminated and has a fucosylated triantennary structure, in the adhesion between germ cells and Sertoli cells. The study of MX is a good example of how the in vivo roles of an apparently redundant gene product are determined by the gene knockout approach.

Histochemical study of glycoconjugates in active and photoperiodically-regressed testis of hamster (Mesocricetus auratus)

The objective of the present study was to characterize glycoconjugates of hamster testis in gonadally-active and -inactive states by lectin histochemical methods. Thirteen HRP- or digoxigenin-labeled lectins were used in samples obtained from fertile and photoinhibited hamsters. In gonadally-active hamsters, spermatozoa tails were stained with Con-A, HPA, PNA, UEA-I, LTA, AAA, WGA and LFA and weakly with GNA and RCA-I. Spermatozoa acrosomes were labeled with HPA, SBA, WGA and PNA. Spermatid acrosomes were labeled with SBA, RCA-I, PNA, and WGA. Staining with GNA and Con-A was found in the Golgi phase and HPA staining was found in the Golgi phase and maturated spermatids. Cytoplasm of spermatocytes was labeled with Con-A, GNA, LTA, AAA, RCA-I, HPA, WGA and LFA, whereas spermatocyte membranes were stained with Con-A, LTA and AAA. Spermatogonia were strongly labeled with Con-A and moderately labeled with AAA, WGA and LFA. Sertoli cells were positive after staining with Con-A, AAA, WGA, and LFA. The lamina propria was positive after staining with UEA-I, LTA, AAA and LFA. Leydig cells showed strong labeling with SBA, Con-A, GNA, SNA and MAA, moderate labeling with WGA, weak labeling with RCA-I, AAA and LFA. In gonadally-inactive hamsters, spermatocytes showed increased staining with HPA, PNA and AAA, whereas staining with Con-A, GNA and LTA had disappeared. Spermatogonia showed an increased labeling with AAA and WGA, but labeling with Con-A and LFA had disappeared. Sertoli cells were strongly labeled with GNA. Con-A and GNA staining was decreased in Leydig cells of gonadally-inactive hamsters but PNA and HPA staining was increased. The lamina propria in regressed testes showed intense labeling with PNA. These results suggest that histological, morphological and hormonal changes occurring in hamster testis during exposure to a short photoperiod are reflected in altered patterns of expression and distribution of N- and O-linked glycans.

Distribution of terminal sugar residues in the testis of the spotted rayTorpedo marmorata

Lectins represent a class of proteins/glycoproteins binding specifically to terminal sugar residues. The present investigation aims to identify lectin-binding sites in testis of Torpedo marmorata. Using a panel of lectins coupled with fluoresceine isothiocyanate, we demonstrated that germ and somatic cells present in Torpedo testis contain glycoconjugates, whose distribution at the level of the surface, the cytoplasm and the nucleus changes during germ cell differentiation. Moreover our observations demonstrate that the germ cells undergoing apoptosis (Prisco et al., 2003a: Mol Reprod Dev 64:341-348) overexpress a residual sugar recognised by WFA lectin that can be considered a specific marker for apoptotic germ cells. Finally, our results indicate that there is a progressive increase in glycosilation during spermatogenesis, especially at the level of the acrosome in the spermatocyte-spermatid step, and that Leydig cells are differently stained in relation to the spermatogenetic cycle.

In vivo role of alpha-mannosidase IIx: ineffective spermatogenesis resulting from targeted disruption of the Man2a2 in the mouse

Alpha-mannosidase IIx (MX) is an enzyme closely related to the Golgi N-glycan processing enzyme alpha-mannosidase II (MII). The enzymatic activity of MX in vitro is minimal. Therefore, the in vivo role of MX in N-glycan processing is as yet unclear. The targeted disruption of the gene encoding MX in the mouse resulted in an obvious phenotype, i.e., MX-deficient males were found to be infertile. Testes from homozygous mutant male mice are smaller than those from wild-type or heterozygous littermates. Histology of the MX null mouse testis showed significant reduction of spermatogenic cells in the seminiferous tubules. Electron microscopy showed that prominent intercellular spaces surround MX-deficient spermatogenic cells, suggesting a failure of germ cell adhesion to Sertoli cells. Quantitative structural analyses of N-glycans from wild-type and MX-deficient mouse testis showed that wild-type testes contain GlcNAc-terminated complex type N-glycans, while they are significantly reduced in MX-deficient mutant testis. An in vitro assay for adhesion of spermatogenic cells to Sertoli cells was carried out. By testing the effect of each purified N-glycan oligosaccharide, it was demonstrated that a GlcNAc-terminated tri-antennary, fucosylated N-glycan has an activity on the adhesion between germ cells and Sertoli cells. Thus, the targeted disruption of the gene encoding MX uncovered a novel carbohydrate recognition system in a biologically important process, spermatogenesis.

Histochemical study of the interstitial tissue in scrotal and abdominal boar testes

The present study describes the glycosidic content of the interstitial tissue in testes from healthy boars and from unilateral and bilateral abdominal cryptorchid boars using lectin histochemistry. The Leydig cells of healthy boars contained glycans with fucosyl, mannosyl, glucosyl, neuraminic acid and galactosyl residues, which have structural and transport functions, and participate in androgen synthesis and in cell regulation. Unilateral cryptorchidism induced high glucosyl and low galactosyl content in the Leydig cells of scrotal testes, resulting in impaired androgen production. In abdominal testes, the Leydig cells exhibited increased amounts of glucosyl and reduced amounts of galactosyl and neuraminic acid residues, resulting in defective cell regulation and lack of androgen synthesis. In healthy boars, the extracellular glycans contained fucosyl, galactosyl, glucosyl and neuraminic acid residues, which confer viscoelasticity on the interstitial tissue and participate in substrate transport, hormone binding and cell-cell interaction. Unilateral cryptorchidism did not induce anomalies in extracellular glycans in scrotal testes, but unilateral and bilateral cryptorchidism resulted in an increased content of fucosyl and galactosyl, and a decreased content of glucosyl and neuraminic acid residues in abdominal testes, leading to reduced viscoelasticity and defective substrate transport across the extracellular matrix.

Lectin affinity of the seminiferous epithelium in healthy and cryptorchid post-pubertal boars

The present study describes the sugar content of the seminiferous epithelium, using lectin histochemistry, in healthy boars and in boars with unilateral and bilateral abdominal cryptorchidism. In healthy boars the apical cytoplasm of Sertoli cells exhibited abundant glucosyl (Con A and WGA lectins), galactosyl (HPA, DBA, SBA and PNA lectins), and fucosyl (AAA lectin) residues. Spermatogonia and spermatocytes contained abundant glucosyl (Con A and WGA lectins) and fucosyl (AAA lectin) residues. In spermatids, galactosyl (SBA and PNA lectins) and glucosyl (Con A and WGA lectins) residues increased progressively throughout spermiogenesis, and fucosyl (AAA lectin) residues decreased. As compared with healthy boars, the scrotal testis of unilateral cryptorchid boars showed decreased amounts of fucosyl (AAA lectin) and galactosyl (HPA and DBA lectins) residues on the Sertoli cell apical cytoplasm; spermatocytes exhibited higher content of glucosyl (Con A lectin) residues and spermatids showed altered nature of glucosyl (Con A and WGA lectins) and galactosyl (SBA and PNA lectins) complexes. In abdominal testes of unilateral and bilateral cryptorchid boars, immature Sertoli cells and spermatogonia showed decreased fucosyl (AAA lectin), and increased glucosyl (Con A and WGA lectins) and galactosyl (SBA and PNA lectins) contents. These results suggest that the seminiferous epithelium of healthy boars has polarized activity with the apical compartment implicated in germ cell-Sertoli cell adhesion and interaction, in transport of ions, substrates and fluids, and in acrosomal differentiation. In scrotal testes, unilateral abdominal cryptorchidism could lead to defective germ cell-Sertoli cell adhesion, impaired acrosomal differentiation and increased ionic transport in the apical compartment of the seminiferous epithelium. Unilateral and bilateral cryptorchidism could induce increased ionic transport and membrane permeability in the seminiferous epithelium of abdominal testes.

Localization of the lectin reactive sites in adult and prepubertal horse testes

The testes of prepubertal and adult horses were investigated using 10 horseradish peroxidase conjugated lectins combined with sialidase digestion and potassium hydroxide treatment, to localise the oligosaccharide sequences of glycoconjugates during spermatid maturation. In adult animals, the lectins showed a variable affinity for spermatids and Sertoli cell apical extensions. Soybean agglutinin (SBA), peanut agglutinin (PNA), Ricinus communis agglutinin (RCA-I) and wheat germ agglutinin (WGA) bound to the acrosomal structures of spermatids, whereas Griffonia simplicifolia agglutinin (GSA-II) labelled these structures only during Golgi and cap phases. These results suggested that glycoproteins of mature acrosomes contain both N- and O-linked oligosaccharides and that these carbohydrate chains undergo modifications during spermiogenesis. Sialic acid residues were not detected throughout the acrosomal development. The lectin binding pattern of Sertoli cells was very similar to that of acrosome of spermatids during the maturation phase. In sexually immature horses, only the degenerated germinal cells and the Leydig cells showed reactivity towards lectins. The first cells reacted with SBA and Dolichos biflorus agglutinin (DBA), the latter with SBA, PNA, WGA, GSA-II, Canavalia ensiformis agglutinin (ConA), Lens culinaris agglutinin (LCA) and also with DBA after sialidase digestion.