Induction of more aggressive tumoral phenotypes in LNCaP and PC3 cells by serum exosomes from prostate cancer patients

Prostate cancer (PCa) is the second most frequent and sixth most fatal cancer in men worldwide. Despite its high prevalence, our understanding of its etiology and the molecular mechanisms involved in the progression of the disease is substantially limited. In recent years, the potential participation of exosomes in this process has been suggested. Therefore, we aim to study the effect of exosomes isolated from the serum of patients with PCa on various cellular processes associated with increased tumor aggressiveness in two PCa cell lines: LNCaP-FGC and PC3. The exosomes were isolated by filtration wand ultracentrifugation. Their presence was confirmed by immunodetection of specific markers and their size distribution was analyzed by Dynamic Light Scattering (DLS). The results obtained demonstrated that serum exosomes from PCa patients increased migration of PC3 cells and neuroendocrine differentiation of LNCaP-FGC cells regardless of the grade of the tumor. PCa serum exosomes also enhanced the secretion of enzymes related to invasiveness and resistance to chemotherapeutics, such as extracellular matrix metalloproteases 2 and 9, and gamma-glutamyltransferase in both cell lines. Altogether, these findings support the pivotal participation of exosomes released by tumoral cells in the progression of PCa. Future studies on the molecular mechanisms involved in the observed changes could provide crucial information on this disease and help in the discovery of new therapeutic targets.

Liver growth factor induces testicular regeneration in EDS-treated rats and increases protein levels of class B scavenger receptors

The aim of the present work was to determine the effects of liver growth factor (LGF) on the regeneration process of rat testes after chemical castration induced by ethane dimethanesulfonate (EDS) by analyzing some of the most relevant proteins involved in cholesterol metabolism, such as hormone sensitive lipase (HSL), 3β-hydroxysteroid dehydrogenase (3β-HSD), scavenger receptor SR-BI, and other components of the SR family that could contribute to the recovery of steroidogenesis and spermatogenesis in the testis. Sixty male rats were randomized to nontreated (controls) and LGF-treated, EDS-treated, and EDS + LGF-treated groups. Testes were obtained on days 10 (T1), 21 (T2), and 35 (T3) after EDS treatment, embedded in paraffin, and analyzed by immunohistochemistry and Western blot. LGF improved the recovery of the seminiferous epithelia, the appearance of the mature pattern of Leydig cell interstitial distribution, and the expression of mature SR-BI. Moreover, LGF treatment resulted in partial recovery of HSL expression in Leydig cells and spermatogonia. No changes in serum testosterone were observed in control or LGF-treated rats, but in EDS-castrated animals LGF treatment induced a progressive increase in serum testosterone levels and 3β-HSD expression. Based on the pivotal role of SR-BI in the uptake of cholesteryl esters from HDL, it is suggested that the observed effects of LGF would facilitate the provision of cholesterol for sperm cell growth and Leydig cell recovery.

Bisphenol-A induces podocytopathy with proteinuria in mice

Bisphenol-A, a chemical used in the production of the plastic lining of food and beverage containers, can be found in significant levels in human fluids. Recently, bisphenol-A has been associated with low-grade albuminuria in adults as well as in children. Since glomerular epithelial cells (podocytes) are commonly affected in proteinuric conditions, herein we explored the effects of bisphenol-A on podocytes in vitro and in vivo. On cultured podocytes we first observed that bisphenol-A-at low or high concentrations-(10 nM and 100 nM, respectively) was able to induce hypertrophy, diminish viability, and promote apoptosis. We also found an increase in the protein expression of TGF-β1 and its receptor, the cyclin-dependent kinase inhibitor p27Kip1, as well as collagen-IV, while observing a diminished expression of the slit diaphragm proteins nephrin and podocin. Furthermore, mice intraperitoneally injected with bisphenol-A (50 mg/Kg for 5 weeks) displayed an increase in urinary albumin excretion and endogenous creatinine clearance. Renal histology showed mesangial expansion. At ultrastructural level, podocytes displayed an enlargement of both cytoplasm and foot processes as well as the presence of condensed chromatin, suggesting apoptosis. Furthermore, immunohistochemistry for WT-1 (specific podocyte marker) and the TUNEL technique showed podocytopenia as well as the presence of apoptosis, respectively. In conclusion, our data demonstrate that Bisphenol-A exposure promotes a podocytopathy with proteinuria, glomerular hyperfiltration and podocytopenia. Further studies are needed to clarify the potential role of bisphenol-A in the pathogenesis as well as in the progression of renal diseases.

Novel role of parathyroid hormone-related protein in the pathophysiology of the diabetic kidney: evidence from experimental and human diabetic nephropathy

Parathyroid hormone-related protein (PTHrP) and its receptor type 1 (PTH1R) are extensively expressed in the kidney, where they are able to modulate renal function. Renal PTHrP is known to be overexpressed in acute renal injury. Recently, we hypothesized that PTHrP involvement in the mechanisms of renal injury might not be limited to conditions with predominant damage of the renal tubulointerstitium and might be extended to glomerular diseases, such as diabetic nephropathy (DN). In experimental DN, the overexpression of both PTHrP and the PTH1R contributes to the development of renal hypertrophy as well as proteinuria. More recent data have shown, for the first time, that PTHrP is upregulated in the kidney from patients with DN. Collectively, animal and human studies have shown that PTHrP acts as an important mediator of diabetic renal cell hypertrophy by a mechanism which involves the modulation of cell cycle regulatory proteins and TGF- β 1. Furthermore, angiotensin II (Ang II), a critical factor in the progression of renal injury, appears to be responsible for PTHrP upregulation in these conditions. These findings provide novel insights into the well-known protective effects of Ang II antagonists in renal diseases, paving the way for new therapeutic approaches.

Hormone-sensitive lipase expression and IHC localization in the rat ovary, oviduct, and uterus

Hormone-sensitive lipase (HSL) is a key regulator of cholesterol esters metabolism. The aim of this study was to determine HSL localization in rat female reproductive organs during the ovarian cycle by IHC methods. HSL was located in the ovarian epithelium. The granulosa cells and oocytes of primordial follicles were immunonegative. In mature follicles, HSL was found in oocytes and theca and granulosa cells. However, HSL expression in theca cells and oocytes decreased during follicular atresia. Luteal cells showed HSL staining in cytoplasm during proestrus and estrus, in the nucleus during metestrus, and in cytoplasm and the nucleus during diestrus. In the tubaric ampulla, HSL was located in the epithelial cells nuclei and in the cilia during proestrus and estrus but mainly in the nucleus during metestrus and diestrus. In the isthmus, cells showed HSL immunolabeling in the nucleus and cilia during proestrus, but only in the cilia during estrus, metestrus, and diestrus. In the uterus, HSL was found in the epithelial cells nuclei. HSL-immunoreactive bands at 84, 67, 54, and 43 kDa were found in rat female reproductive organs. HSL labeling in the nucleus of epithelial and germ cells suggests an as yet unknown function for this protein, probably related to oogenesis and cell proliferation.

Influence of thyroid hormone receptors on breast cancer cell proliferation

BACKGROUND

The involvement of thyroid hormones in the development and differentiation of normal breast tissue has been established. However, the association between breast cancer and these hormones is controversial. Therefore, the objective of the present study was to determine the protein expression pattern of thyroid hormone receptors in different human breast pathologies and to evaluate their possible relationship with cellular proliferation.

PATIENTS AND METHODS

The presence of thyroid hormone receptors was evaluated by immunohistochemistry and western blot analysis in 84 breast samples that included 12 cases of benign proliferative diseases, 20 carcinomas in situ and 52 infiltrative carcinomas.

RESULTS

TR-alpha was detected in the nuclei of epithelial cells from normal breast ducts and acini, while in any pathological type this receptor was located in the cytoplasm. However, TR-beta presented a nuclear location in benign proliferative diseases and carcinomas in situ and a cytoplasmatic location in normal breast and infiltrative carcinomas. The highest proliferation index was observed in carcinomas in situ, although in infiltrative carcinomas an inverse correlation between this index and the TR-alpha expression was encountered.

CONCLUSIONS

The results of this study reveal substantial changes in the expression profile of thyroid hormone receptors suggesting a possible deregulation that could trigger breast cancer development.

Expression of vitamin D3 receptor and retinoid receptors in human breast cancer: identification of potential heterodimeric receptors

Vitamin D3 (VD) and all-trans-retinoic acid (ATRA) have been postulated as a novel treatment option for breast carcinoma. Since the combined effects of retinoids and VD derivatives are attributed to heterodimeric interactions between members of the nuclear receptor family, the expression patterns of the heterodimers formed by vitamin D3 receptor (VDR) and the retinoid receptors RARs (RAR-alpha, RAR-beta and RAR-gamma) and RXRs (RXR-alpha, RXR-beta and RXR-gamma) have been studied by immunohistochemistry in benign and malignant breast tissues. Present results revealed that immunoexpressions to all receptor types studied were higher in both in situ and infiltrative carcinomas than in benign breast diseases. In a variable number of cases of infiltrative carcinoma, immunostaining appeared in the nucleus, whereas in the other two disorders immunostaining was only cytoplasmic. The correlation established between VDR and the different isoforms of retinoid receptors revealed that VDR seems to select mainly RAR-alpha to form heterodimers and to exert their properties as transcription factor. The results of this study suggest that this heterodimer plays a critical role in cancer malignancy, and its presence indicates those patient groups presenting a better response to adjuvant therapies based on the combination of vitamin D and ATRA.

Cloning, expression, and regulation by androgens of a putative member of the oxytocinase family of proteins in the rat prostate

BACKGROUND

Proteases are relevant in the physiology of the prostate, and its expression is regulated by androgens.

METHODS

Isolation of a novel cDNA from the rat prostate was done by reverse transcriptase-polymerase chain reaction and rapid amplification of cDNA ends. By Northern blot, we analyzed the RNA expression in different tissues and in the prostate after orchidectomy and androgen treatment. By using in situ hybridization, we studied the cellular localization of the RNA.

RESULTS

The cDNA codes a putative novel form of the vp-165 aminopeptidase family of proteins that we named short-vp. The short-vp probe labels one mRNA of 1.3 kb in the prostate, brain, testis, heart, and kidney. In the prostate, the levels of short-vp mRNA decrease after orchidectomy and increase with testosterone treatment. The short-vp mRNA is expressed by the prostatic epithelial cells.

CONCLUSION

We isolated one putative member of the oxytocinase family of proteins that is expressed in various tissues and by the epithelial cells of the prostate. The expression of short-vp mRNA in the prostate depends on androgen levels.

Immunohistochemical detection of the retinoid acid receptors (RXR-alpha, -beta, -gamma) and Farnesoid X-activated receptor (FXR) in the marbled newt along the annual cycle

Retinoid acid receptors (RXR-alpha, -beta, -gamma) and Farnesoid X-activated receptor (FXR) expression in the testis of the marbled newt were investigated with special attention to the changes during the annual testicular cycle, using light microscopy immunohistochemistry and Western blot analysis. The annual testicular cycle of the marbled newt (Triturus marmoratus marmoratus) comprises three periods: (a) proliferative period (germ cell proliferation from primordial germ cells to round spermatids, April-June); (b) spermiogenesis period (July-September); and (c) quiescence period (interstitial and follicular cells form the glandular tissue, October-April). In the proliferative period, primordial germ cells and primary spermatogonia immunostained intensely to the three types of RXRs and also to FXR. In the other periods, immunostaining to these antibodies was weak or absent. Secondary spermatogonia stained weakly to the four antibodies in the proliferative period, and only to FXR, also weakly, in the spermiogenesis period. Immunoreactive primary spermatocytes were weakly labeled with the RXR antibodies in the proliferative period. Spermatids and spermatozoa did not stain to any antibody in any period. Follicular cells only immunostained to RXR-gamma and only in the quiescence period when they are forming the glandular tissue, together with the interstitial cells. As follicular cells, interstitial cells only immunostained in the quiescence period; however, they immunoreacted to the three types of RXRs. These findings suggest that in the newt, RXRs and FXR are involved in spermatogenesis control by regulating the proliferation of primordial germ cells and spermatogonia. In addition, RXR-gamma seems to be also involved in the development of the glandular (steroidogenic) tissue.

Immunoexpressions of p21, Rb, mcl-1 and bad gene products in normal, hyperplastic and carcinomatous human prostates

A comparative study of the expression of p21, Rb, mcl-1, and bad gene products, which are involved in the control of the cell cycle, was performed in normal, hyperplastic, and carcinomatous human prostates by means of a semiquantitative immunochemical study. This included Western blot, ELISA, and immunohistochemistry procedures. In normal prostates, immunoexpression of the four gene products was scanty or absent. In men with benign prostatic hyperplasia, immunoreactions to the four proteins studied were found in many epithelial cells and some stromal cells. In prostatic carcinoma, the immunostaining pattern was as in hyperplastic prostates but the numbers of both epithelial and stromal cells were higher. Present results indicate that immunoexpression of p21, Rb (both the phosphorylated and dephosphorylated forms), mcl-1, and bad gene products are markedly increased in prostates with proliferative alterations but that these proteins do not discriminate between benignant (hyperplasia) and malignant (adenocarcinoma) prostatic tumours, although immunoexpression is higher in prostatic carcinoma.

Androgen receptor (AR), estrogen receptor-alpha (ER-alpha) and estrogen receptor-beta (ER-beta) expression in the testis of the newt, Triturus marmoratus marmoratus during the annual cycle

Expression of androgen receptor (AR), estrogen receptor alpha (ER-alpha) and estrogen receptor beta (ER-beta) in the testis of the marbled newt (Triturus marmoratus marmoratus) was investigated, with special attention to changes during the annual testicular cycle, using light microscopy immunohistochemistry and Western blot analysis. Primordial germ cells, primary and secondary spermatogonia and spermatocytes showed a positive reaction to the 3 receptor antibodies during the annual reproductive cycle. Follicular cells were positive to AR, ER-alpha and ER-beta during the spermiogenesis and quiescence periods in the glandular tissue. Interstitial cells showed reactivity to AR, ER-alpha and ER-beta in the spermiogenesis and the quiescence periods, and presented no labelling to these receptors in the proliferative period. These findings suggest that, as in mammals, there is an androgen-estrogen regulation of the function and development of the newt testis.

E-, N- and P-cadherin, and alpha-, beta- and gamma-catenin protein expression in normal, hyperplastic and carcinomatous human prostate

The expression of E-, N- and P-cadherin, alpha-, beta- and gamma-catenin, and actin was studied by immunohistochemistry, ELISA, and Western blot analysis in normal prostates, and in the prostates of men with benign prostatic hyperplasia and men with prostatic carcinoma, in order to evaluate their possible role in the pathogenesis of these diseases. Present results reveal that the immunophenotype of hyperplastic prostates differs from those of both normal and carcinomatous prostates in the intracellular distribution (observed by immunohistochemistry) and the intensity (measured by ELISA) of immunoreactions to cadherins, catenins, and actin. Hyperplastic prostates differ form normal prostates in the weaker immunoreaction to the three cadherin types, the two catenins, and actin, as well as in the intracellular distribution of P-cadherin, beta- and gamma-catenin, and actin. Differences between benign prostatic hyperplasia and prostatic carcinoma are less marked because hyperplastic prostates differ from carcinomatous prostates only in the weaker immunoreactions to P-cadherin, and alpha-catenin. The most remarkable findings in this study were: (1) alpha-catenin production was elevated in prostatic carcinoma in comparison with benign prostatic hyperplasia and normal prostate; and (2) P-cadherin expression in benign prostatic hyperplasia is reduced with regard to those of normal and carcinomatous prostates. It may be concluded that a decreased immunoreaction to cadherins, catenins, and actin, as well as changes in the intracellular distribution of actin in prostatic cells are not necessarily suggestive of malignancy, because these alterations are also present in BPH, and thus, the loss of cadherin-catenin-mediated adhesion alone is not sufficient to establish an invasive phenotype.

Estrogen receptors alpha and beta in the normal, hyperplastic and carcinomatous human prostate

Two different estrogen receptors (ER-alpha and ER-beta) have been described, which are differentially involved in regulating the normal function of reproductive tissues. ER-alpha was considered for a long time to be the only estrogen receptor, and it has been detected in the stromal cells of the human prostate but not in the epithelium. To obtain new information about the differential effects of both receptor types, we have investigated their localization in normal prostates, benign prostatic hyperplasia (BPH), and prostatic cancer (PC) by immunohistochemistry, ELISA and Western blot. Epithelial immunostaining was absent in normal prostates and was present in BPH (10% of cells) and PC (80% of cells), whereas about 15% of stromal cells were positively immunostained for ER-alpha in the three types of prostatic specimens studied. Epithelial immunostaining for ER-beta was detected in normal prostates (13% of cells), BPH (30% of cells) and PC (79% of cells), whereas stromal immunostaining for ER-beta was absent in normal and hyperplastic prostates and was present in PC (12% of cells). The complementary presence of both receptor types in the normal prostate (ER-beta in the epithelium and ER-alpha in the stroma) might explain the mechanism of estrogen action in the development of BPH. The increased epithelial immunostaining for both ER-alpha and ER-beta in BPH and PC suggests that the involvement of estrogen receptors in hyperplasia and cancer concerns mainly the epithelium.

Morphometric evaluation of the human prostate

In order to clarify the ageing-related histological changes in the human prostate, a quantitative morphometric analysis was performed. Complete prostates were obtained at autopsy from 281 men (aged 20-84 years) who died in traffic accidents and presented no clinical symptoms of prostatic disease. The prostates were classified as: histologically normal (n=182), with nodular hyperplasia (n=42), with intraepithelial neoplasia (n=40) and carcinomatous with low Gleason grade (n=20). Each prostate was divided into three regions (periurethral, central and peripheral) and the volume of each region, as well as the average volume occupied by stroma and epithelium in each region were quantified. For each parameter, the average values for each age group were compared. In the histologically normal prostates, an increase with ageing in the total volume and the volume occupied by the central region were observed; these increases were mainly caused by an increase in the stromal volume of the central region in men after 30 years of age. No histologically normal prostates were found in men older than 70 years of age. Nodular prostatic hyperplasia was found in men over 30 years of age and a fluctuation in the total volume throughout ageing was observed. Prostates with intraepithelial neoplasia (PIN) and carcinoma were observed in men aged >20 years and the total volume and those of each prostatic region showed multiple variations, except for the eighth decade where a marked increase with regard to that of the previous decades was observed.

Identification of N- and O-linked oligosaccharides in human seminal vesicles

The main oligosaccharide residues and the saccharide linkage in infantile and adult human seminal vesicles were studied by means of lectin histochemistry at light and electron microscopy levels. In adult glands, the epithelial cell cytoplasm and luminal content reacted positively to the following residues: (GlcNAc)n (WGA), Galbeta1,3GalNAc (PNA), GalNAcalpha1,3Gal (SBA), GalNAcalpha1,3GalNAc (HPA), Fucalpha1,2Galbeta1,4GlcNAc (UEA-I), and alphaL-Fuc1,6DGlcNAc-O-Melibiosc (AAA). The presence of intense staining in the luminal content suggest that glycoproteins containing these oligosaccharide moieties are secreted by epithelial cells. Adult epithelial cells also reacted to Neu5Acalpha2,6Gal (SNA), Neu5Acalphaa2,3Galbeta1,4GlcNAc (MAA), Galbeta1,4GlcNAc (DSA), branched mannose chains (ConA), Man1,3Man (GNA), and Fucalpha1,2Galbeta1,4GlcNAcFucalpha1,3GlcNAc (LTA) but reaction to these residues was weak (MAA, DSA, ConA, and LTA) or absent (SNA and GNA) in the gland lumen, which suggests that they belong to intracytoplasmic proteins. The chemical and enzymatic treatments used suggest that the residues recognized by SNA, MAA, PNA, DSA, HPA, and SBA belong to O-linked oligosaccharides; those residues localized by ConA and GNA have an N-glycosidic linkage, and those bound by WGA, LTA, UEA-I, and AAA are linked to both N- and O-oligosaccharides. In prepubertal seminal vesicles, reaction in the epithelial cell cytoplasm was similar to that observed in adults, except for GNA and HPA, which showed a weaker reaction. However, the lumen of prepubertal seminal vesicles showed intense reaction to WGA and SBA only. The chemical and enzymatic treatments suggest that the scanty glycoproteins secreted by the prepubertal glands belong to the mucin-type.

Immunohistochemical localization of protein gene product 9.5, ubiquitin, and neuropeptide Y immunoreactivities in epithelial and neuroendocrine cells from normal and hyperplastic human prostate

This study was designed to investigate (a) the presence of protein gene product 9.5 (PGP 9.5), ubiquitin, and neuropeptide Y (NPY) in the neuroendocrine and secretory epithelium of the human normal prostate and its secretions, and (b) the changes in immunoreactivity to these proteins in men with benign prostatic hyperplasia. Western blotting and light microscopic immunohistochemistry techniques were used and the numerical density of immunoreactive neuroendocrine cells, and the volume fractions of immunostained secretory epithelium were evaluated. Western blotting revealed the presence of the three antigens in both tissue homogenates and prostate secretion. Some neuroendocrine cells immunoreacted to PGP 9.5 and NPY in all the prostate regions of control specimens. Ubiquitin immunoreactivity was detected in the nuclei from both basal cells and secretory epithelial cells. The cytoplasm of the secretory cells and the glandular lumen also showed immunostaining for the three proteins. The numerical densities of both PGP 9.5 and NPY neuroendocrine cells were lower in hyperplasia than in controls. No differences in the volume fraction occupied by epithelial immunostaining to both proteins was found between hyperplastic and control prostates. We concluded that (a) PGP 9.5 and NPY, but not ubiquitin, are common antigens in both neuroendocrine and secretory prostate cells, (b) the three immunoreactive proteins contribute to the prostate secretions, and (c) the secretion of ubiquitin is markedly diminished in the hyperplastic epithelium.(J Histochem Cytochem 48:1121-1130, 2000)

Interferon-gamma and its functional receptors overexpression in benign prostatic hyperplasia and prostatic carcinoma: parallelism with c-myc and p53 expression

The therapeutic potential of IFN-gamma in prostatic cancer has been documented in several reports, although no immunohistochemical studies of this factor and its receptors in the prostate have been reported. The aim of the present study was to investigate the expression of IFN-gamma and its receptor components (IFN-gamma-Ralpha and IFN-gamma-Rbeta) in normal prostate, benign prostatic hyperplasia (BPH) and prostatic cancer (PC), as well as the possible relationship between this factor and the products of the p53 gene (the wild and mutant forms) and the oncogene c-myc, by means of immunochemical techniques (Western blot, ELISA, and quantification of immunostaining in histological sections). In normal prostate, IFN-gamma and its two receptors were expressed in the basal cells of the epithelium and some stromal cells. In BPH specimens, immunostaining of basal epithelial cells was significantly increased for IFN-gamma and its a receptor, whereas stromal cell immunostaining was significantly increased for IFN-gamma and its b receptor. In addition, columnar epithelial cells immunostained for IFNbeta-Rbeta. PC specimens differed from BPH specimens in the significantly increased immunostaining of epithelial cells for IFN-gamma and its two receptors, and the immunostaining of columnar epithelial cells for IFN-gamma-Ralpha. Immunodetection of wild-p53 was weak and limited to some stromal cells in the three types of specimens. Immunostainings for both mutant-p53 and c-myc were negative in normal prostate, and positive in the epithelium and stromal cells of both BPH and PC specimens. Immunostaining intensity in PC was significantly higher than in BPH. These observations suggest that the expression of both mutant-p53 and c-myc, together with other factors, might be involved in the development of prostatic hyperplasia and neoplasia, while the increased expression of IFN-gamma and its receptors could be regarded as an attempt, although insufficient, to inhibit the uncontrolled cell proliferation.

Characterization of several invertebrate muscle cell types: a comparison with vertebrate muscles

Ultrastructural classification of invertebrate muscles is complex and not always clear. The aim of the present paper was to establish some criteria that might be useful for classification of invertebrate muscles and for a better understanding of the differences between them. The procedures used were: (1) immunochemical evaluation of those proteins that differentiated striated from smooth muscle (troponin, caldesmon, and calponin), and (2) calculations of several myofilament parameters to establish differences among muscles. The muscles studied were: striated muscles from the rat, Drosophila, the crab Callinectes, and the snail Helix (heart); obliquely striated muscles from the earthworm Eisenia foetida and Helix (mouth); and smooth muscles from the rat, and Helix (retractor, body wall, and intestinal wall). Immunochemical studies revealed that troponin was only present in the striated muscles and the obliquely striated muscle from Eisenia, whereas caldesmon and calponin were only present in the smooth muscles and the obliquely striated muscle from Helix. The highest thick filament/thin filament volume ratio was found in the striated muscles, followed by the obliquely striated muscles, and the smooth muscles. This suggests the order in which the contraction strength decreases. The myofilament length is inversely related to the contraction speed, which was higher in the striated muscles than in the obliquely striated muscles. In vertebrates, the smooth muscle seems to be less rapid than the striated muscle because their myofilaments are longer. This assertion cannot be generalized for invertebrate smooth muscle, because myofilament lengths vary widely in both striated and smooth muscles. In smooth muscles, the presence of apparently unordered electron-dense bodies instead of ordered Z lines and the absence of true sarcomeres permit a certain overlapping of thin filaments increasing the range of shortening.

IL-2, its receptors, and bcl-2 and bax genes in normal, hyperplastic and carcinomatous human prostates: immunohistochemical comparative analysis

The presence of interleukin-2 (IL-2) and its receptors (Ralpha, Rbeta, Rgamma), and their relationship with the products of bcl-2 and bax genes was studied in normal prostates, benign prostatic hyperplasia (BPH), and prostatic cancer (PC) by ELISA, Western blot, and immunohistochemistry. A comparative semiquantitative immunohistochemical study was also performed. For all the antibodies assayed, immunoreactions were found in the epithelium and some stromal cells in the three types of specimens studied. These immunoreactions were much more higher in PC samples than in normal prostates. In BPH, immunoreactions were similar to that of normal prostates (bax), similar to that of PC (IL-2 and its three receptors), or intermediate between that of normal prostates and that of PC (bcl-2). Immunoexpressions of IL-2 and its receptors were found in the epithelial basal cells and some stromal cell of normal prostates and might be related to the control of the proliferation-apoptosis equilibrium. The increased expressions of IL-2 and its receptors in the epithelium of prostates in BPH, associated with increased bcl-2 expression which would account for the decrease in the apoptosis index that has been reported in this disorder. The increased expression of both bcl-2 and bax in PC might be involved in the higher apoptosis index reported in PC specimens. Since IL-2 administration seems to have an anti-tumour effect, the increased expression of this interleukin in BPH and PC could be interpreted as an attempt to hinder cell proliferation which would only be efficient at high doses.

A lectin histochemistry comparative study in human normal prostate, benign prostatic hyperplasia, and prostatic carcinoma

The partial oligosaccharide sequences of glycoconjugates and the nature of their glycosidic linkages were investigated in normal human prostate, benign prostatic hyperplasia (BPH) and prostatic carcinoma by means of lectin histochemistry, using light microscopy and Western blot analysis. The labeling pattern of BPH differed from that of normal prostate in having more intense staining with DSA, HPA, UEA-I and AAA, and in showing lesser staining with WGA and SBA. Prostatic carcinoma differed from normal prostates in displaying the more intense labeling with PNA, DSA, SBA, DBA, UEA-I and AAA, and in having lesser labeling with WGA. The main differences in labeling pattern between prostatic carcinoma and BPH were that the latter specimens showed more marked staining with PNA, DSA, DBA, SBA, UEA-I and AAA, and lesser staining with WGA and HPA. The staining patterns of SNA, MAA, ConA, LCA and GNA were similar in all three groups of specimens. For most of the lectins studied, including those showing a similar immunohistochemical staining in the three groups of specimens studied, the Western blot analysis showed differences in the banding pattern among normal, hyperplastic, and carcinomatous prostates. Present results suggest that the glycosylation of proteins was modified in both BPH and prostatic carcinoma. In BPH a strong expression of N-acetylgalactosamine residues occurred, while in prostatic carcinoma an increase of sialic acid, galactose and fucose residues was observed. No changes in mannose residues were detected.

The hatching gland cells of trout embryos: characterisation of N- and O-linked oligosaccharides

A histochemical, light and electron microscopy study of the hatching gland cells (HGCs) in incubated 50-d-old trout embryos is reported. The distribution of carbohydrate residues in the glycoconjugates of these cells was studied by means of a battery of 13 different lectins conjugated with horseradish peroxidase (PNA, ConA, LCA, WGA, SBA, UEA-I, HPA, DBA) or digoxigenin (DSA, MAA, AAA, SNA, GNA). Identification of N- and O-linked oligosaccharides in HGCs was performed by application of both chemical and enzymatic treatments. Present results suggest that HGCs are seromucous cells which store both high choriolytic enzyme (HCE) and low choriolytic enzyme (LCE), and that their cytoplasmic granules, endoplasmic reticulum and Golgi complex contain additional sialic acid-rich glycoproteins. The negative charge of these glycoproteins might be responsible for the rapid expansion of mucin to form a highly hydrated gel, which would facilite the action of these enzymes in programmed cell death and might play a major role during the morphogenic events.

Lectin histochemistry of the human testis

The oligosaccharide sequences of glycoconjugates and the nature of the saccharide linkage were investigated in normal human testes by means of lectin histochemistry studies, at light and electron microscopy levels. Reaction to WGA was intense in the seminiferous epithelium and interstitium. MAA showed light reactivity in all cell types of the human seminiferous epithelium, the lamina propria and Leydig cells. UEA-I lectin labelled the lamina propria intensely and the seminiferous epithelium and Leydig cells slightly. A slight reaction to AAA was found in the seminiferous epithelium and in Leydig cells. ConA was labelled in Sertoli cells, germ cells and Leydig cells. The reaction to GNA lectin was similar although less intense. PNA labelling was slight in Sertoli cells, spermatogonia, and Leydig cells, and more intense in spermatocytes, spermatids and peritubular cells. Reaction to DSA was intense in the seminiferous epithelium and Leydig cells. HPA labelled all cell types in the seminiferous epithelium and Leydig cells slightly, and labelled peritubular cells intensely. SBA lectin showed a strong reaction in spermatids and a slight reaction in the lamina propria. The reactions to SNA, LTA, and DBA were negative in all testicular cell types. After beta-elimination pre-treatment, MAA, UEA-I, AAA, PNA, DSA, HPA and SBA reactions were all negative. Endo F/PNGase digestion suppressed reactivity to ConA y GNA. Staining for WGA decreased with Endo F/PNGase digestion and also after beta-elimination. Desialization increased reactivity to PNA, SBA and HPA lectins. These results indicate that the terminal sequences of oligosaccharide side-chains in spermatocytes and, principally, in spermatids are: fucose, mannose, Neu5Ac2,3Gal1,3GalNAc, Gal1,3GalNAc, Gal1,4GlcNAc, Neu5AcGalNAc and GalNAc (in O-glycosylated proteins); mannose (in N-glycosylated proteins) and GlcNAc (in both protein types). A sialic acid residue is added to galactose and GalNAc residues. Present findings also indicate that Sertoli cell glycoproteins are similar to those of spermatids, and that the terminal sugar residues in Leydig cells are GlcNAc, fucose, mannose, Neu5Ac2,3Gal1,3GalNAc, Gal1,3GalNAc, and Gal1,4GlcNAc. The lectin pattern of the lamina propria suggests the presence of GlcNAc, galactose, fucose and GalNAc.

Lectin histochemistry study in the human vas deferens

The oligosaccharide sequences of glycoconjugates in the normal human vas deferens and the nature of the saccharide linkage were studied by lectin histochemistry. The cytoplasm of all epithelial cell types (principal cells, basal cells, and mitochondria-rich cells) and luminal contents reacted positively with WGA, MAA, PNA, DSA, LTA, UEA-I, AAA, and ConA. The reaction was more intense in the stereocilia of principal cells. Cytoplasmic staining was diffuse except for PNA and DSA labeling which was limited to the apical cytoplasm and stereocilia of columnar cells. The cytoplasm of all cell types also reacted diffusely with HPA, although staining was weak and was not observed in the stereocilia. Positive reaction with SBA only was encountered in the stereocilia of principal cells. SNA, LTA, and DBA were unreactive. GNA-labeling showed a granular distribution in the supranuclear cytoplasm of columnar epithelial cells. Reactions with MAA, PNA, DSA, AAA, HPA and SBA disappeared after the beta-elimination reaction. Reactions with WGA and UEA-I decreased after beta-elimination or Endo-F digestion. Reactions with ConA and GNA were suppressed by Endo-F digestion. Reactions with PNA, HPA, and SBA increased after desialylation. Of all the lectins that label the luminal contents of the vas deferens, only UEA-I was not found in the luminal contents of seminiferous tubules and epididymis and, thus, this lectin would probably bind to glycoproteins secreted by the vas deferens. The chemical treatments used suggest that this secretion contains fucose residues located in both N- and O-linked oligosaccharides. The other lectins may label secreted proteins, but also structural proteins or proteins reabsorbed from the luminal fluid. The lectin- binding pattern of mitochondria-rich cells in the vas deferens differed from that found in the epididymis.

Identification of N- and O-linked oligosaccharides in the human epididymis

The oligosaccharide sequences of glycoconjugates in the human normal epididymis and the nature of linkages were studied with lectin histochemistry. The usual terminal sequences of oligosaccharide side chains in epithelial cell secretions were Neu5Ac2,3Galbeta1,3GalNAc; SO4Galbeta1,3GalNAc; and Galbeta1,4GlcNAc, and they were mainly found in O-linked glycoproteins. The lectin pattern of mitochondria-rich cells differed from that of principal cells.

Intermediate filaments in the Sertoli cells of the ageing human testis

The presence and distribution of intermediate filaments (vimentin, keratin, desmin) was studied in the Sertoli cells of elderly men by means of quantitative immunohistochemical methods. Sertoli cells from young men showed moderate immunogold labelling to vimentin throughout the entire cytoplasm between the cell organelles in tubules showing complete spermatogenesis. Immunogold particles were more numerous in the perinuclear cytoplasm and beneath the plasma membrane in all its faces. The testes from elderly men showed different tubule types; some showed complete spermatogenesis and a normal lamina propria, while others had spermatogenic arrest at different levels (spermatids, spermatocytes, spermatogonia). The immunohistochemical reaction to vimentin in the Sertoli cells of tubules with complete spermatogenesis (type a) was similar to that in the cells of young men. In the Sertoli cells of severely damaged tubules (type b) the immunohistochemical reaction was more intense and immunogold particles extended in similar proportions throughout the whole cytoplasm. When immunolabelling intensity was compared between the three groups of tubules, by counting the number of immunogold particles per square micrometre of cytoplasm, it was found to be significantly higher (P < or = 0.05) in type b tubules of elderly men than either in tubules of young men or in type a tubules of elderly men. Since the average cell surface of Sertoli cells was similar in all tubule types, these data suggest that an actual vimentin increase occurs in Sertoli cells of germ-cell-depleted tubules. Sertoli cell immunogold labelling to keratin was found neither in young men nor in type a tubules of ageing men, whereas a positive immunohistochemical reaction was observed in the Sertoli cells of type b tubules of elderly men. Immunogold particles were localized mainly in the perinuclear cytoplasm, and beneath the lateral and basal cell surfaces. The observation of vimentin increase and keratin re-expression in ageing Sertoli cells only in germ-cell-depleted tubules suggests that the changes in intermediate filaments are related to the local factors associated with completion of spermatogenesis, causing functional changes in Sertoli cells.

Immunocytochemical and quantitative study of the tunica albuginea testis in young and ageing men

A light and electron microscope immunohistochemical study of the tunica albuginea from both young and elderly men was carried out to determine the distribution of the cells that contain actin, vimentin and/or desmin, and to evaluate the possible variations with ageing by means of quantitative studies. Testicular volume and testicular parenchyma volume decreased significantly with age whereas the tunica albuginea volume remained unchanged. These results agree with the scanty quantitative changes observed in the testicular connective tissue with age, and the notion that age-related changes in testicular volume are principally restricted to the seminiferous tubules. Three connective tissue layers could be distinguished in the tunica albuginea in both young and elderly men. The middle and inner layers increased in width with age while the width of the outer layer decreased. The average width of the tunica albuginea increased significantly with ageing. The tunica albuginea of young men and elderly men presented two types of fusiform cells: (1) fibroblast-like cells, which immunoreacted to actin and vimentin, but not to desmin; and (2) myoid cells, which immunoreacted to actin, vimentin and desmin. In both young men and elderly men, the total number of desmin-positive cells (myoid cells) was significantly lower than that of fibroblasts. However, the total number of desmin-positive cells was significantly increased in ageing men. In young testes, desmin-positive cells were more abundant in the outer layer of the tunica albuginea, whereas in elderly men these cells predominated in the middle layer. The increased desmin immunoexpression in the tunica albuginea of ageing men contrasts with the decrease in desmin immunoreaction in other myoid cells of the testis, the peritubular myoid cells, but only in seminiferous tubules that showed severe germ cell depletion. This suggests that changes in intermediate filament immunoexpression in peritubular cells are focalised, and thus, under local control, whereas changes in the tunica albuginea cells are generalised and possibly related to factors also affecting the connective tissue in other organs.

Immunocytochemical and quantitative study of actin, desmin and vimentin in the peritubular cells of the testes from elderly men

A quantitative immunohistochemical study using light and electron microscopy was carried out to evaluate the morphological and quantitative distribution of the peritubular cells that immunoreact with actin, vimentin and desmin, alone or in combinations, in normal adult testes and the changes in these cells in elderly men. Seminiferous tubules in ageing testes were classified in three groups according to the degree of lamina propria thickening due to tubular sclerosis: group I, < 8 microns; group II, 8.1-12 microns; and group III, > 12.1 microns. The number of peritubular cells per cross-sectioned tubule increased from group I to group III tubules. However, no significant differences between ageing men and controls were found in the total number of peritubular cells per testis. Most peritubular cells of control testes and of group I and group II tubules displayed immunoreactivity to actin. The peritubular cells in the outermost layers of group III tubules showed no or scanty reaction. The number of actin-immunostained cells per cross-sectioned tubule decreased (P < 0.05) with tubular sclerosis. The total number of these cells per testis was significantly lower (P < 0.05) in elderly men. A narrow band around the seminiferous epithelium immunostained for desmin in control testes and group I tubules. These cells also immunoreacted to actin and vimentin. In group II and, principally, in group III tubules, only isolated peritubular cells were immunostained for desmin. The number of desmin-immunostained cells per cross-sectioned tubule decreased with tubular sclerosis and the total number per testis was also lower in elderly men. Vimentin immunostaining was observed in most peritubular cells in all tubule groups; these cells also immunoreacted to actin. Vimentin and desmin co-localized only in the inner peritubular cell layers. The number of vimentin-immunostained cells per cross-sectioned tubule increased with the degree of tubular sclerosis but the total number of these cells per testis did not differ significantly between control and ageing testes.

Light and electron microscopic immunohistochemical localization of protein gene product 9.5 and ubiquitin immunoreactivities in the human epididymis and vas deferens

The distribution of protein gene product 9.5 (PGP) and ubiquitin immunoreactivities in the ductuli efferentes, ductus epididymidis, and ductus deferens of humans was studied by Western blot analyses and light and electron microscopic immunocytochemistry. PGP immunoreactivity was intense in the ductuli efferentes and weak in the ductus epididymidis and ductus deferens, while ubiquitin immunoreactivity was intense in the ductuli efferentes and ductus epididymidis and very weak in the ductus deferens. In the ductuli efferentes epithelium, PGP immunolabeling was observed in the cytoplasm of principal cells, whereas ubiquitin immunoreactivity was found in the nucleus and cytoplasm of principal cells and ciliated cells. In the ductus epididymidis epithelium, only scattered cells (mitochondria-rich cells) showed PGP immunoreaction in their cytoplasm, whereas ubiquitin immunostaining was detected in the nucleus and cytoplasm of most epithelial cells, except for the cauda, where ubiquitin immunolabeling was observed only in the nuclei. The ductus deferens showed no immunostaining for PGP, and only nuclear immunoreactivity to ubiquitin. The ultrastructural localization of PGP immunoreactivity was in the apical cytosol and microvilli. In addition to these locations, ubiquitin immunoreactivity was also found in the nucleus of all cell types and cilia of ciliated cells. Although the distribution of PGP and ubiquitin immunoreactivities in humans differs from that reported in rats, it seems that PGP and ubiquitinated proteins are secreted into the epididymal lumen in both species.

Testicular cell cytoskeleton in the newt, Triturus marmoratus marmoratus, during the annual cycle

Light and electron microscopy immunohistochemical studies and Western blotting analysis of cytoskeletal proteins have been carried out in the testis of the marbled newt (Triturus marmoratus marmoratus) during the annual testicular cycle. The present findings revealed homologies and differences with regard to those reported in the testes of mammals and other vertebrates. Changes in immunohistochemical expression have also been detected in the course of the annual cycle. Actin and tubulin, which were scanty and diffusely located in spermatogonia and spermatocytes, increased their expression and reorganized during spermiogenesis. Vimentin and keratin, undetected in spermatogonia and spermatocytes, were expressed in differentiating spermatids and spermatozoa. In these cells, actin might be related with the connection of the axial fiber to the undulating membrane and the coordination of movement by both structures, while vimentin might be involved in the maintenance of the spatial relationship between the axoneme and the marginal fiber. During the first stages of spermatogenesis, the cytoplasm of Sertoli cells (follicular cells) showed a diffuse immunoreaction to actin, myosin, and tubulin and no vimentin immunolabeling. In advanced spermiogenesis, the follicular cells showed an intense immunoreaction to actin, myosin, tubulin, and vimentin in the apical projections that surrounded the spermatid heads. These apical cytoskeletal components might be involved in spermatid elongation, since the spermatids display no manchette, and in spermatozoon positioning and grouping. The colocalization of myosin and actin in the follicular cells suggests that actin filaments from contractile bundles and that contraction might be involved in changes in the Sertoli cell shape that accompany germ cell development during spermatogenesis. The interstitial cells immunostained to actin, myosin, tubulin, and vimentin. These cells, together with follicular cells, seemed to form the glandular tissue cells which showed a similar immunophenotype. The cells that surrounded the efferent duct epithelium immunostained to desmin, and they are probably contractile cells involved in sperm evacuation.

Immunocytochemical electron microscopic study and western blot analysis of paramyosin in different invertebrate muscle cell types of the fruit fly Drosophila melanogaster, the earthworm Eisenia foetida, and the snail Helix aspersa

The presence and distribution pattern of paramyosin have been examined in different invertebrate muscle cell types by means of Western blot analysis and electron microscopy immunogold labelling. The muscles studied were: transversely striated muscle with continuous Z lines (flight muscle from Drosophila melanogaster), transversely striated muscle with discontinuous Z lines (heart muscle from the snail Helix aspersa), obliquely striated body wall muscle from the earthworm Eisenia foetida, and smooth muscles (retractor muscle from the snail and pseudoheart outer muscular layer from the earthworm). Paramyosin-like immunoreactivity was localized in thick filaments of all muscles studied. Immunogold particle density was similar along the whole thick filament length in insect flight muscle but it predominated in filament tips of fusiform thick filaments in both snail heart and earthworm body wall musculature when these filaments were observed in longitudinal sections. In obliquely sectioned thick filaments, immunolabelling was more abundant at the sites where filaments disappeared from the section. These results agree with the notion that paramyosin extended along the whole filament length, but that it can only be immunolabelled when it is not covered by myosin. In all muscles examined, immunolabelling density was lower in cross-sectioned myofilaments than in longitudinally sectioned myofilaments. This suggests that paramyosin does not form a continuous filament. The results of a semiquantitative analysis of paramyosin-like immunoreactivity indicated that it was more abundant in striated than in smooth muscles, and that, within striated muscles, transversely striated muscles contain more paramyosin than obliquely striated muscles.

Lectin histochemistry in the human epididymis

A histochemical study using lectins to identify glycoconjugates present in the efferent ducts and ductus epididymidis of men without testicular or related disease was carried out. The lectins used and the oligosaccharide residues linked were: wheat germ agglutinin (WGA) for beta-N-acetylglucosamine and sialic acid, concanavalin A (ConA) for alpha-mannose, Ulex europaeus agglutinin (UEA-I) for alpha-fucose, Dolichos biflorus agglutinin (DBA) for alpha-N-acetylgalactosamine, soy bean agglutinin (SBA) for beta-N-acetylgalactosamine, and peanut agglutinin (PNA) for beta-galactose. The lectin-binding pattern in the human epididymis presents similarities and differences to those observed in other mammals which also showed differences between species. The present results revealed that regional differences along the human ductus epididymidis were less pronounced than those reported in other mammals. The epithelial cells in the efferent ducts reacted positively to WGA. All along the length of the ductus epididymidis, the principal cells and the luminal content showed staining affinity for WGA and ConA. The epididymal principal cells and luminal content also reacted positively to DBA for alpha-N-acetylgalactosamine but only in the cauda epididymidis. A positive reaction to UEA-I was observed only in the luminal content of the cauda epididymidis. This finding suggests that changes in the oligosaccharide chains of secretions leading to a positive UEA-I reaction occur in the cauda epididymidis. The epididymal principal cells showed positive reactions to SBA and PNA over the apical microvilli but not in the cytoplasm. The reaction was observed in the caput and corpus epididymidis but not in the cauda. Positive reactions to SBA and PNA were also detected in the epididymal fluid and in the cytoplasm of mitochondria-rich cells (a minor population of epididymal epithelial cells). These cells also reacted to other lectins such as WGA, ConA and DBA, which were also detected in the principal cells.

Immunocytochemical electron microscopic study and Western blot analysis of troponin in striated muscle of the fruit fly Drosophila melanogaster and in several muscle cell types of the earthworm Eisenia foetida

BACKGROUND

There is little information about troponin in invertebrate muscles, and no previous references to this protein in annelid muscles have been found. The aim of this paper was to study the presence and distribution of troponin in different muscle cell types from the earthworm Eisenia foetida (the muscular body wall, and the inner and outer muscular layer of the pseudoheart). These results were compared with those obtained in the transversely striated muscle of Drosophila melanogaster and in skeletal and smooth muscles of the mouse.

METHODS

Immunocytochemical electron microscopic study and Western blot analysis using anti-TnT antibodies were employed in this study.

RESULTS

Troponin immunoreaction was detected in the mouse skeletal muscle, the fly flight muscle, and earthworm obliquely striated muscles (body wall musculature and inner muscular layer of the pseudoheart). Immunolabeling for TnT in all these muscle cells appeared in moderate amounts at any point along the sarcomere length, except for the central zone of the A band (H band). This suggests that troponin molecules were located along the thin filaments. The density of immunogold particles was similar in the three muscles, and thus the amount of troponin in each muscle type was proportional to the number and length of actin filaments in each. Troponin was found in neither the mouse smooth muscle nor the outer muscular layer of the earthworm pseudoheart. The latter muscle showed an ultrastructural pattern that was intermediate between obliquely striated and smooth muscle. The estimated molecular weight for TnT in the earthworm was 55 kDa; this is higher than the weight of this protein in the mouse skeletal muscle (40 kDa) but similar to that of the D. melanogaster muscle (52 kDa).

CONCLUSIONS

Troponin is present in both types of striated muscle (transversely striated and obliquely striated) of the earthworm with a distribution that is very similar to that observed in the mammalian striated muscle. As in vertebrates, troponin is absent in the smooth muscle of the earthworm. Discrepancies in the classification of some invertebrate muscles are common in the literature, and the use of distinctive markers, such as troponin, may improve our understanding of the nature and properties of many invertebrate muscles showing an ultrastructural pattern that does not resemble any of the classic muscle types.

Intermediate filaments in the testis of the teleost mosquito fish Gambusia affinis holbrooki: a light and electron microscope immunocytochemical study and western blotting analysis

A light and electron microscope immunocytochemical study and Western blotting analysis has been performed on intermediate filaments (vimentin, desmin and cytokeratins) in the testis of the teleost fish Gambusia affinis holbrooki. An immunoreaction to vimentin was observed in the epithelium of the efferent ducts, testicular canal and their surrounding peritubular cells. Positive vimentin immunostaining was also observed in the cells located around seminiferous tubules (boundary cells), Leydig cells, interstitial fibroblasts, chromatophores, and blood vessel endothelial cells. In contrast to mammals, no vimentin immunoreactivity was found in the Sertoli cells. Immunoreactivity to desmin was weak in the epithelial cells of the efferent ducts and testicular canal and intense in the peritubular cells that surrounded these ducts. Desmin immunoreactivity was also observed in the seminiferous tubule boundary cells. The immunoreactivity was weak in the boundary cells that surrounded germ cell cysts containing spermatogonia or spermatocytes and intense in the boundary cells around cysts with elongated or mature spermatids. Immunoreactivity towards cytokeratins was observed only in testicular blood vessels. Cytokeratin immunolabelling was intense in the endothelium and weak in the vascular smooth muscle cells. No cytokeratin immunoreactivity was found in the Sertoli cells, germ cells, interstitial cells or in the efferent duct epithelium. The absence of intermediate filaments in the Sertoli cells, the absence of cytokeratins in the epithelium of the sperm excretory ducts, and the presence of desmin filaments in these epithelial cells are the most important differences with regards to the intermediate filament phenotype in mammalian testes.

Cytoskeleton in Sertoli cells of the mosquito fish (Gambusia affinis holbrooki)

BACKGROUND

There is little information about the distribution of cytoskeletal components in the testes of teleost fish. The aim of this paper was to know the distribution of some major cytoskeletal proteins (tubulin, actin, vimentin, desmin, and cytokeratins) in the Sertoli cells of Gambusia affinis holbrooki and in their efferent duct epithelial cells which are possibly originated from the Sertoli cells.

METHODS

Light and electron microscopic immunocytochemical studies and Western blotting analysis were performed in G. affinis testis.

RESULTS

Actin immunoreaction was observed in the Sertoli cells at all spermatogenic stages, although the intensity of this reaction varied from one stage to another. Sertoli cells that support spermatogonia or spermatocytes showed a weak immunoreaction which was uniformly distributed throughout the cytoplasm and somewhat more concentrated at the level of the inter-Sertoli specialized junctions. Immunoreaction to actin increased during the first stages of spermiogenesis and was mainly localized beneath the plasma membrane. This immunoreaction was more intense in the basal than in the apical cytoplasm of Sertoli cells. In a more advanced stage of spermiogenesis, actin immunoreaction become stronger in the apical cytoplasm where Sertoli cells displayed cytoplasmic projections around each spermatid. After sperm release, the apical Sertoli cell cytoplasm still showed an intense actin immunoreaction. Intense immunoreaction to actin was also observed in the epithelial cells lining the efferent ducts. Immunoreaction to tubulin was diffuse throughout the Sertoli cell cytoplasm. No immunoreaction to vimentin or desmin was observed in the Sertoli cells during the spermatogenic process. Immunoreaction to both vimentin and desmin was observed in the efferent duct cells. Desmin immunoreaction was also observed in the seminiferous tubule boundary cells, mainly in the sections showing germ cell cysts at the last stages of spermiogenesis and in the peritubular cells that surrounded the efferent duct epithelium. Immunoreaction to cytokeratins was found in the endothelium of testicular blood vessels but not in the Sertoli cells or in the efferent duct epithelium.

CONCLUSIONS

Immunoreaction pattern to cytoskeletal proteins in the Sertoli cells of G. affinis differs from that reported in mammalian Sertoli cells. These differences include the distribution of actin filaments and the absence of detectable vimentin immunoreaction in G. affinis Sertoli cells.