Peritubular Smooth Muscle Cells Research Articles

Knockout of the polysialyltransferases ST8SiaII and ST8SiaIV leads to a dilatation of rete testis during postnatal development.

Polysialic acid (polySia) is a carbohydrate polymer that modulates several cellular processes, such as migration, proliferation and differentiation processes. In the brain, its essential impact during postnatal development is well known. However, in most other polySia positive organs, only its localization has been described so far. For instance, in the murine epididymis, smooth muscle cells of the epididymal duct are polysialylated during the first 2weeks of postnatal development. To understand the role of polySia during the development of the epididymis, the consequences of its loss were investigated in postnatal polySia knockout mice. As expected, no polysialylation was visible in the absence of the polysialyltransferases ST8SiaII and ST8SiaIV. Interestingly, cGMP-dependent protein kinase I (PGK1), which is essentially involved in smooth muscle cell relaxation, was not detectable in peritubular smooth muscle cells when tissue sections of polySia knockout mice were analyzed by immunohistochemistry. In contrast to this signaling molecule, the structural proteins smooth muscle actin (SMA) and calponin were expressed. As shown before, in the duct system of the testis, even the expression of these structural proteins was impaired due to the loss of polySia. We now found that the rete testis, connecting the duct system of the testis and epididymis, was extensively dilated. The obtained data suggest that less differentiated smooth muscle cells of the testis and epididymis result in disturbed contractility and thus, fluid transport within the duct system visible in the enlarged rete testis.

The Loss of Polysialic Acid Impairs the Contractile Phenotype of Peritubular Smooth Muscle Cells in the Postnatal Testis.

In the testis, the germinal epithelium of seminiferous tubules is surrounded by contractile peritubular cells, which are involved in sperm transport. Interestingly, in postnatal testis, polysialic acid (polySia), which is also an essential player for the development of the brain, was observed around the tubules. Western blotting revealed a massive decrease of polySia from postnatal day 1 towards puberty, together with a fundamental reduction of the net-like intertubular polySia. Using polysialyltransferase knockout mice, we investigated the consequences of the loss of polySia in the postnatal testis. Compared to postnatal wild-type animals, polySia knockouts showed slightly reduced smooth muscle actin (SMA) immunostaining of peritubular smooth muscle cells (SMCs), while calponin, marking more differentiated SMCs, dramatically decreased. In contrast, testicular SMA and calponin immunostaining remained unchanged in vascular SMCs in all genotypes. In addition, the cGMP-dependent protein kinase PKG I, a key enzyme of SMC relaxation, was nearly undetectable in the peritubular SMCs. Cell proliferation in the peritubular layer increased significantly in the knockouts, as shown by proliferating cell nuclear anti (PCNA) staining. Taken together, in postnatal testis, the absence of polySia resulted in an impaired differentiation of peritubular, but not vascular, SMCs to a more synthetic phenotype. Thus, polySia might influence the maintenance of a differentiated phenotype of non-vascular SMCs.

Seasonal expressions of androgen receptor, P450arom and estrogen receptors in the epididymis of the wild ground squirrel (Citellus dauricus Brandt)

The aim of this study was to investigate the seasonal expressions of androgen receptor (AR), estrogen receptors alpha and beta (ERα and ERβ) and aromatase cytochrome P450 (P450arom) in the epididymis of the wild ground squirrel. Histologically, the epididymis was with larger duct diameter and cell population during the breeding season. AR was presented in the peritubular smooth muscle cells and epithelial cells in the whole epididymis with stronger staining in the breeding period. P450arom was intensely localized in epithelial cells and spermatozoa during the breeding season, absent in the non-breeding season and moderately stained in pre-hibernation. During the breeding season, ERα was intensely expressed in epithelial cytoplasm and/or nucleus, whereas in the non-breeding season and pre-hibernation, weaker staining signal was found in nucleus of epithelial cells. ERβ was absent in the entire annual cycle by immunohistochemical and Real-time PCR detection. The mRNA levels of AR, P450arom and ERα were higher in the epididymis of the breeding season when compared to those of the non-breeding season and pre-hibernation. Taken together, these results suggest that epididymis of the wild ground squirrel is a primary target for androgen and estrogen, and the expression of P450arom represents that epididymis may be a potential source of estrogen.

Immunohistochemical localization of androgen receptor in rat caput epididymis during postnatal development

Objectives: The aim of this study was to investigate the developmental pattern of androgen receptor (AR) in caput epididymis. Materials and methods: In this study three randomly selected rats were sacrificed at ages 21, 56, 90 and 120 days old. All male rats were anesthetized with ethyl ether before killing. Then, the caput epididymides were removed and fixed in Bouin's fixative at +4dC for 36 hour. Afterwards the tissue samples were embedded in paraffin for routine histological methods. Later the tissues were sectioned at 5mm and mounted on poly-L-lysin-coated slides. To solve the antigen masking problem, we performed microwave stimulated antigen retrieval technique before the immunohistochemical staining. Avidin-Biotin-Peroxidase Complex (ABC) method was applied for immunohistochemical staining. Results: In all age groups of rats studied, positive immunohistochemical staining for the AR appeared in nuclei of epididymal cells. The staining intensity of AR positive cells did not change depending on age. In caput epididymis, immunostainable AR was found in tubular epithelial cells (principal cells, basal cells and apical cells) and peritubular smooth muscle cells. The AR staining in the epithelial cells appeared to be stronger than in the peritubular smooth muscle cells. In the epithelial cells; staining intensity was stronger in principal cells than in basal cells and apical cells. Conclusion: Staining intensity of AR positive epididymal cells irrespective of age indicated the necessity of androgens for postnatal differentiation and maintaining the structure of the epididymis. Stronger staining intensity in principal cells suggested that principal cells are more sensitive to androgen stimulation.

The effects of prepubertal epididymal ligation upon androgen receptor distribution in the rat caput epididymis

The aim of the present study was to investigate the androgen receptor (AR) distribution in epididymal cells of developing rats and the effects of prepubertal epididymal obstruction upon AR distribution in the rat caput epididymis. At 15 days of age, the young rats were divided at random into groups for epididymal ligation or sham operation. In the ligation group the corpus epididymides were ligated bilaterally; in the sham group only laparatomy was performed. Both groups were sacrificed at 21, 56, 90, 120 days. The epididymes were removed, fixed in Bouin's fixative and embedded in paraffin wax. The tissues were sectioned at 5 μm and stained using the microwave stimulated antigen retrieval technique for immunohistochemistry. The features of the immunohistochemical staining of caput epididymal cells for the AR were similar across both groups. The operation did not affect AR distribution in caput epididymis. Positive immunohistochemical staining for the AR appeared in nuclei but not in the cytoplasm of caput epididymal cells at all ages beginning from 21 to 120 days old. The staining intensity of AR-positive cells did not change depending on age. In the caput epididymis, immunostainable AR were found in tubular epithelial cells (principal cells, basal cells and apical cells) and interstitial stromal cells (peritubular smooth muscle cells). There were no significant histological alterations in epididymal epithelium.

Peritubular Contractile Cells in Testis and Epididymis of the Dog, Canis lupus familiaris

Contractile cells surrounding the tubular system of the mammalian testis and epididymis are supposed to contribute to the initial transport of spermatozoa from the testis to epididymis. Testicular peritubular smooth muscle cells have been characterised in detail especially in rodents and humans. The aim of our study was to assess the distribution of peritubular contractile cells of the canine tubuli seminiferi, rete testis channels, ductuli efferentes, and ductus epididymidis by immunohistochemistry and transmission electron microscopy and to classify these cells with respect to their possible physiological function. The entire tubular system of the canine testis and epididymis is surrounded by contractile cells expressing smooth muscle actin, smooth muscle myosin and desmin, which are enveloped, at least partly, by a basal lamina. Some contractile cells of the tubuli seminiferi, rete channels, and efferent ducts and sometimes also single peritubular cells of the ductus epididymidis express vimentin. Contractile cells of seminiferous tubules and efferent ducts represent an intermediate cell type exhibiting characteristics of both smooth muscle cells (SMC) and myofibroblasts, those of rete channels stellate myofibroblasts, and those of the ductus epididymidis SMC. Differences in structure and arrangement of the contractile cells between seminiferous tubules, rete channels, efferent ducts, and ductus epididymidis suggest different functions. Myofibroblasts and contractile cells similar to them could be mainly responsible for the maintenance of an appropriate tissue turgor, whereas contraction of SMC of the ductus epididymidis might cause propulsion of spermatozoa by peristaltic waves.

NAADP‐induced Ca2+ signaling in response to endothelin is via the receptor subtype B and requires the integrity of lipid rafts/caveolae

We have investigated the role of NAADP-mediated Ca(2+) mobilization in endothelin (ET) signaling via endothelin receptor subtype A (ETA) and endothelin receptor subtype B (ETB) in rat peritubular smooth muscle cells. Microinjection and extracellular application of NAADP were both able to elicit Ca(2+) release which was blocked by inhibitory concentrations of NAADP, by impairing Ca(2+) uptake in acidic stores with bafilomycin, and by thapsigargin. Ca(2+) release in response to selective ETB stimulation was abolished by inhibition of NAADP signaling through the same strategies, while these treatments only partially impaired ETA-dependent Ca(2+) signaling, showing that transduction of the ETB signal is dependent on NAADP. In addition, we show that lipid rafts/caveolae contain ETA, ETB, and NAADP/cADPR generating enzyme CD38 and that stimulation of ETB receptors results in increased CD38 activity; interestingly, ETB- (but not ETA-) mediated Ca(2+) responses were antagonized by disruption of lipid rafts/caveolae with methyl-beta-cyclodextrin. These data demonstrate a primary role of NAADP in ETB-mediated Ca(2+) signaling and strongly suggest a novel role of lipid rafts/caveolae in triggering ET-induced NAADP signaling.

Endothelin induces functional hypertrophy of peritubular smooth muscle cells

When chronically stimulated with agonists of contraction, smooth muscle cells (SMCs) undergo cell hypertrophy, a process defined as increase in size and potentiation of the contractile phenotype in the absence of proliferation. Hypertrophic response has long been associated to a number of pathologies of the cardiovascular and respiratory systems. We have investigated the phenotypic and functional response of SMCs to long-term treatment with endothelin. Our model was primary cultures of peritubular smooth muscle cells (PSMC) a testicular cell type target of locally produced endothelin and characterized by an unusual phenotypic stability when cultured in simple medium in complete absence of serum. We report the following responses of PSMC to 4-day exposure to ET-1: (i) increased protein synthesis without induction of cell proliferation; (ii) increase in cell size (evaluated by means of flow cytometry) and increased expression of SM-alpha-actin, desmin, caldesmon and calponin, markers of the contractile phenotype. In experiments of selective stimulation of either ETA or ETB receptor subtypes, both proved to be involved in inducing the observed hypertrophic responses. The hypertrophic cells exhibit the ultrastructural features of differentiated SMCs and are capable of calcium mediated contractile response when acutely stimulated with ET-1 specifically through ETA and/or ETB receptors, as evaluated by calcium imaging and scanning electron microscopy. These observations demonstrate that engagement of ET receptors is capable of inducing potentiation of the contractile phenotype and functional hypertrophy of PSMC.

Platelet‐derived growth factor‐BB‐induced hypertrophy of peritubular smooth muscle cells is mediated by activation of p38 MAP‐kinase and of Rho‐kinase

Peritubular smooth muscle cells (PSMC) from rat testis in primary serum-free cultures unexpectedly undergo contraction and subsequent cell hypertrophy in response to the growth factor PDGF-BB, remaining stationary. The present study investigates the transduction pathways involved in the observed paradoxical upregulation of the differentiated phenotype and induction of hypertrophy in PSMC. PI3K, ERK, JNK, and p38 kinases, known to mediate PDGF-BB signaling in the canonic dedifferentiative and proliferative response of smooth muscle cells (SMC) were rapidly activated by PDGF-BB but only p38 remained activated after 2-day stimulation. Immunofluorescence and immunoblotting experiments showed that in 4-day treatment: (i) continuous inhibition of PI3K, of ERK, of JNK, failed to inhibit either cell enlargement and formation of prominent alpha-SM actin containing stress fibers or the typical increase in alpha-SM actin; (ii) when stimulated in the presence of the p38 inhibitor SB203580 both responses were significantly inhibited and cytofluorimetric analysis of cell size showed a remarkable reduction of the hypertrophic response. PDGF-BB was also found to activate the small GTPase RhoA and inhibition of Rho-dependent kinase ROCK by Y27632 counteracted the effects of PDGF-BB similarly to SB203580. Both the transcription factor ATF2 and the nucleosomal kinase MSK1, downstream targets of p38, were activated by PDGF-BB, but p38 inhibitor SB203580 inhibited only the phosphorylation of MSK1 which appeared unaffected by ROCK inhibitor Y27632. In concluding, p38 and the Rho-ROCK system were found to play prominent, probably independent roles in the upregulation of PSMC differentiated phenotype and induction of hypertrophy by PDGF-BB.

A pivotal role for cADPR-mediated Ca2+ signaling: regulation of endothelin-induced contraction in peritubular smooth muscle cells.

cADPR, a potent calcium-mobilizing intracellular messenger synthesized by ADP-ribosyl cyclases regulates openings of ryanodine receptors (RyR). Here we report that in the rat testis, a functional cADPR Ca2+ release system is essential for the contractile response of peritubular smooth muscle cells (PSMC) to endothelin (ET). We previously showed that this potent smooth muscle agonist elicits intracellular Ca2+ release in PSMC and seminiferous tubule contraction via activation of ETA and ETB receptors. ETB-R induces the mobilization of a thapsigargin-sensitive but IP3-independent intracellular Ca2+ pool. Stimulation of permeabilized PSMC with cADPR was found to elicit large Ca2+ releases blocked by either a selective antagonist of cADPR or a RyR blocker, but not by heparin. Western blotting and confocal fluorescence microscopy indicated the specific expression of type 2 RyR in perinuclear localization. ET was found to stimulate the activity of ADP-ribosyl cyclase. Microinjection of the selective cADPR antagonist 8NH2-cADPR completely abolished subsequent stimulation of Ca2+ signaling via ETA and ETB receptors. cADPR therefore appears to have an obligatory role for ETA-R and ETB-R-mediated calcium signaling in PSMC. However, ETB-R seem to be coupled exclusively to cADPR whereas ETA-R activation may be linked to IP3 and cADPR signaling pathways.

Cell-cell interactions in the local control of seminiferous tubule contractility

Since peritubular smooth muscle cells (PSMCs) have been characterized, isolated and cultured in homogeneous populations, the regulation of seminiferous epithelium contractility has received increasing attention. The present article reports and discusses experimental evidence demonstrating that: (1) PSMCs express two types of high affinity receptors for endothelin (ET-A and ET-B), both responsible for calcium-mediated cell contraction, but coupled to partially different transduction pathways; (2) the production of endothelin by seminiferous epithelium follows a finely regulated spatial and temporal pattern, which is based on the cyclic expression of endothelin-converting-enzyme in Sertoli cells; and (3) a further local factor, PDGF-BB, is capable of stimulating PSMC contraction when acutely administered and induces cell hypertrophy and potentiation of contractile phenotype when chronically administered, in the absence of any proliferative response. The study of the mechanisms through which PSMC contractile activity and differentiated state is locally controlled may be of potential relevance to our knowledge of how the efficiency of tubular output is regulated in normal and pathological conditions.

Function and localization of oxytocin receptors in the reproductive tissue of rams

Oxytocin is present in the male reproductive tract and has been shown to increase contractility in the epididymis and to modulate steroidogenesis. This study investigated the effects of oxytocin in the testis in vivo, and the presence and cellular localization of oxytocin receptors in the reproductive tract of rams. During the breeding season, mature rams underwent efferent duct ligation before injection of either oxytocin (20 microg) or oxytocin plus an oxytocin antagonist (20 microg) into the testicular artery; the contralateral testicular artery received saline. Injection of oxytocin caused a significant increase (P < 0.05) in the concentration of spermatozoa collected from the rete testis. This effect was not observed after treatment with the oxytocin antagonist plus oxytocin. Western blot analysis performed using a specific oxytocin receptor antibody (020) identified a single immunoreactive band of 66 kDa in testicular and epididymal tissue. This band was present in uterine tissue but not in liver or muscle. Immunocytochemistry identified oxytocin receptors on Leydig and Sertoli cells of the testis, on epithelial cells throughout the epididymis, on peritubular smooth muscle cells in the cauda epididymidis, and on the epithelial cells and circular smooth muscle layer of the ductus deferens. These findings indicate that oxytocin can modulate sperm transport in the ram testis. A role for oxytocin in promoting sperm transit is supported by the localization of oxytocin receptors in the cauda epididymis and ductus deferens, and the presence of receptors on Leydig, Sertoli and epididymal epithelial cells provides further evidence that oxytocin may be involved in the local regulation of steroidogenesis.

Mesenchymal cell precursors of peritubular smooth muscle cells of the mouse testis can be identified by the presence of the p75 neurotrophin receptor.

In the mouse embryo, at approximately 11.5 days postcoitum (dpc), cells migrate from the mesonephros into the developing testis to contribute to the somatic population of the interstitial compartment (i.e., peritubular myoid cells, Leydig cells, and endothelial cells). Studies from this laboratory have shown that the interstitial population of mesenchymal cells in fetal and newborn mouse testis express the p75 neurotrophin receptor (p75NTR, formerly known as the low-affinity nerve growth factor receptor); part of the cell population progressively congregates around testis cords, later to be replaced by contractile peritubular myoid cells, which express smooth muscle cell markers. In the present study, we show that the migrating cells and the p75NTR-expressing cells are the same population. We also show that the neurotrophin receptor is a useful endogenous marker to follow cell migration within the urogenital ridge and to identify and isolate mesenchymal precursors of myoid cells. A time-course immunolocalization study of the location of p75NTR-bearing cells within the urogenital ridge of mouse embryos between 10.5 and 12.5 dpc showed that the interstitium of the fetal testis was progressively occupied by p75NTR+ cells. The progressive increase of p75NTR expression within the developing testis was confirmed by immunoblot analysis of proteins isolated from the fetal gonads. Organ cultures of isolated testes or testis-mesonephros grafts confirmed that p75NTR+ cells do not appear in the testis unless a mesonephros is attached to it. Cells bearing the p75NTR receptor, purified from 12.5-dpc male mouse mesonephroi by immunomagnetic sorting, were able to differentiate in vitro into myoid cells. Immunofluorescence analysis of postnatal testis sections confirmed the presence around the tubules of cells coexpressing p75NTR and alpha-smooth muscle actin. The ability to identify and purify precursors of myoid cells may be of considerable help for studying the mechanisms regulating their differentiation.

Platelet-derived growth factor-BB stimulates hypertrophy of peritubular smooth muscle cells from rat testis in primary cultures.

The tunica propria of seminiferous tubules contains a particular type of smooth muscle cell (myoid cells) arranged in a contractile epithelioid layer that is responsible for sperm and tubular fluid flow. Unlike other types of smooth muscle (SM) cells, highly purified populations of peritubular smooth muscle cells (PSMC) survive and maintain their contractile phenotype in primary cultures in controlled conditions. We used this culture model to investigate the response of the SM contractile phenotype to prolonged exposure to platelet-derived growth factor (PDGF), one of the main factors involved in vascular SM pathologies. We observed that 4-day continuous exposure of PSMC to PDGF-BB at nanomolar concentrations in plain medium enhances contractile phenotype traits and induces cell hypertrophy without inducing proliferation. In Northern and Western blotting experiments, SM-alpha-actin transcript and protein were found to be markedly increased in the PDGF-BB-treated samples, which is in line with the formation of conspicuous SM-alpha-actin-containing stress fibers. Moreover, binding sites for endothelin-1 were increased, and the calcium response to the contractile agonist, determined in single fura-2-loaded cells, was enhanced. In response to PDGF-BB, the cells underwent immediate, transient contraction, as seen in a scanning electron microscope, followed by a gradual increase in size, as evaluated by cytofluorometry, and enhancement of protein synthesis. The observed pattern of response to PDGF-BB was not accompanied by cell proliferation, as assessed by [3H]thymidine incorporation and direct cell counts. Unlike other SM cell types, in which proliferation and loss of contractile traits are induced by PDGF, chronic treatment of PSMC with this growth factor results in hypertrophy rather than hyperplasia.

Platelet-Derived Growth Factor-BB Stimulates Hypertrophy of Peritubular Smooth Muscle Cells from Rat Testis in Primary Cultures

Platelet-Derived Growth Factor-BB Stimulates Hypertrophy of Peritubular Smooth Muscle Cells from Rat Testis in Primary Cultures

Regulation of androgen and estrogen receptors in male excurrent ducts of the goat: an immunohistochemical study.

Since androgens and/or estrogens must bind with specific receptors in order to elicit a response at the target organ(s), it is important to understand factors that regulate expression of androgen receptors (AR) and estrogen receptors (ER). Hence, the objective of the study is to determine the relative significance between circulating androgen (CA) and luminal androgen (LA) in maintaining normal expression of AR and ER in male excurrent ducts. Mature Nubian goats were subjected for 15 days each to the following treatments: (1) bilateral orchidectomy, (2) bilateral orchidectomy and testosterone treatment, (3) unilateral ligation of the extratesticular rete, and (4) unilateral orchidectomy. Tissues from different segments of the excurrent ducts were fixed in 4% paraformaldehyde and embedded in Paraplast-plus. Antigenic sites for AR and ER were immunolocalized using PG-21 rabbit antirat/human antibody and H-222 rat antihuman monoclonal antibody, respectively. The avidin-biotin horseradish peroxidase procedure was used to identify positive immunoreactivity. Negative controls included incubation of sections with irrelevant IgG in place of primary antibody. In intact animals, whereas AR were found in epithelial, connective tissue, and peritubular smooth muscle cells of the efferent ductules, regions I-V of the epididymis, and ductus deferens, ER were confined to nonciliated cells of the efferent ductules. Bilateral orchidectomy caused a severe loss of both AR and ER staining. Testosterone replacement to orchidectomized animals restored staining of both AR and ER to the intact level. Neither unilateral ligation of the extratesticular rete nor unilateral orchidectomy had any effect on AR or ER immunostaining. Circulating androgen alone, without any input from luminal androgen or other rete fluid contents, can regulate expression of both androgen receptor and estrogen receptor.

Immunolocalization of receptors for androgen and estrogen in male caprine reproductive tissues: unique distribution of estrogen receptors in efferent ductule epithelium.

Androgens and estrogens affect physiological processes in the testis and male excurrent duct system. This study was designed to identify and characterize distribution of androgen receptors (AR) and estrogen receptors (ER) in the reproductive organs of the male goat. Tissues, including testis, efferent ductules, epididymis (regions I-V), and ductus deferens, were obtained from five mature Nubian goats, fixed in 4% paraformaldehyde, and embedded in paraplast. Antigenic sites for AR were unmasked by microwave treatment (four times, 5 min each) of tissue sections immersed in 10 mM citrate (pH 6) and were detected using the PG-21 rabbit anti-rat/human antibody. Antigenic sites for ER were identified using the H-222 rat anti-human monoclonal antibody after tissue sections were treated with pronase (0.5 mg/ml, 37 degrees C, 8 min). Avidin-biotin horseradish peroxidase procedures were used to identify positive immunoreactivity. Irrelevant IgG was substituted for primary antibody in negative controls. Positive nuclear immunostaining for AR was observed in all types of epithelial cells, peritubular smooth muscle cells, and intertubular fibroblasts of the intratesticular rete, efferent ductules, epididymis (regions I-V), and ductus deferens, as well as in Sertoli, Leydig, and peritubular myoid cells and intertubular fibroblasts of the testis. In contrast, nuclear immunostaining for ER was confined to nonciliated cells of the efferent ductules. Thus, AR-positive cells are ubiquitously distributed in caprine testicular and excurrent ductular tissues, and ER-positive cells are unique to the efferent ductules. The caprine model should be useful in studies designed to determine mechanisms through which androgens and estrogens regulate development and function of the testes and excurrent ducts.

Isolation and characterization of epididymal epithelial cell plasma membranes.

Sperm maturation and storage occur in a unique milieu created in large part by the epididymal epithelium. To learn more about the interaction of the epididymal epithelial cell with both luminal and systemic environments, we now report on the preparation and characterization of epididymal epithelial cell plasma membranes. A preparation enriched for epididymal epithelial cell plasma membranes was isolated from collagenase-digested epididymal tubule fragments by hand-Dounce homogenization, differential centrifugation, and sucrose gradient centrifugation. The final membrane fraction was enriched 11-fold for the plasma membrane marker 5'-nucleotidase; 2.6-fold for the lysosomal marker acid phosphatase, and 3-fold for the Golgi marker thiamine pyrophosphatase. No enrichment was observed for mitochondrial or endoplasmic reticulum enzyme markers. Specific and saturable transferrin-binding activity was also detected in the final preparation. Electron microscopy revealed the presence of vesicles and sheets of membranes as well as an occasional Golgi apparatus. The plasma membrane fraction was used to generate monoclonal antibodies. Of 102 wells exhibiting growth, 12 were positive by immunofluorescent staining of frozen sections. Ten of these recognized determinants in epithelial cells, and 2 stained peritubular smooth muscle cells. Most of the epithelial cell-specific antibodies stained brush border alone or in combination with the basolateral plasma membrane. Three antibodies stained the Golgi apparatus. Most antibodies were specific for particular epididymal regions, 3 also recognized determinants in the kidney, and 1 stained residual bodies in the testis.

Myosin-like microfilaments in the human normal and pathological testis

The immunofluorescent staining of the human normal testis shows that both peritubular and tubular cells bind antimyosin-like antibodies. The same cells are provided with a large amount of microfilaments within the cytoplasm. The thin microfilaments observed by electron microscopy in various cells of the human testis likely correspond to the sites of immunofluorescent staining. In pathological specimens there can be observed a decrease in peritubular smooth muscle cells associated with a decrease in cytoplasmic microfilaments and in the immunofluorescent staining of some cells.