流式细胞术测定睾丸和附睾中生精细胞DNA含量

目的 :观察睾丸和附睾各段组织管腔内生精细胞DNA含量的变化。　方法 :利用流式细胞术 (FCM) ,对15例有生育能力、意外死亡的青年捐献者的右侧新鲜睾丸和附睾 (头、体、尾 )组织管腔内生精细胞的DNA含量进行测定。　结果 :从睾丸至附睾尾均存在单倍体 (1n)、二倍体 (2n)和四倍体 (4n) 3种细胞。 1n细胞由 (2 4 .87±7.2 8) %增至 (96 .33± 1.5 8) % ,其中睾丸至附睾每段之间的差异有极显著性 (P <0 .0 1) ,附睾体与附睾尾之间也有明显差别 (P <0 .0 5 )。 2n和 4n细胞的比例分别由 (6 3.0 7± 8.96 ) %、(9.4 3± 3.83) %下降至 (2 .4 7± 0 .93) %、(1.17± 0 .95 ) %。睾丸至附睾每段之间 2n细胞的比例差异有极显著性 (P <0 .0 1) ,附睾体与附睾尾之间也有明显差别(P <0 .0 5 ) ;除睾丸与附睾头之间的 4n细胞变化不明显外 (P >0 .0 5 ) ,其他各段之间的 4n细胞比例差异也有显著性 (P <0 .0 5 )。　结论 :未成熟生精细胞比例在附睾转运过程中逐渐减少     

TGF-beta could be involved in paracrine actions in the epididymis of the marmoset monkey (Callithrix jacchus).

The transforming growth factor-beta1 (TGF-beta1) and the transforming growth factor-beta receptor type II (TGF-betaRII) were studied in the epididymis of sexually mature marmoset monkeys (Callithrix jacchus) by immunohistochemical localization of the protein and by polymerase chain reaction (PCR) analysis of the mRNA level. In order to specify reactive cell types, the morphology of all three segments (caput, corpus, and cauda epididymidis) was evaluated by light microscopy. Six different cell types could be distinguished: principal, basal, apical, and clear cells, as well as intraepithelial lymphocytes and macrophages. Using immunohistochemistry, specific staining for TGF-beta1 in the caput was found in 47% of the apical cells, whereas the TGF-betaRII was located in the apical portion of 91% of all principal cells. In the corpus epididymidis, 20% of the apical cells were immunopositive for TGF-beta, and binding of the receptor antibody occurred in 17% of the principal cells (all numbers based on counts of counterstained nuclei). All differences between percentages in the caput and corpus were significant as determined by chi-square test. PCR analysis revealed detectable levels of TGF-beta1 mRNA in the marmoset epididymis. Our results indicate for the first time that TGF-beta1 is synthesized in the marmoset epididymis, possibly in a different subpopulation of epididymal cells than the TGF-beta receptor type II. Thus, TGF-beta might be of functional relevance in the primate epididymis.     

Gamma-glutamyl transpeptidase activity in the epididymis during fetal and postnatal development in rats.

The histochemical and biochemical distributions of gamma-glutamyl transpeptidase (gamma-GT) were investigated in the epididymis of rats during fetal and postnatal development. In the epididymal homogenates, gamma-GT activity was detected on the fifth day after birth. A sharp increase was observed after 30 days of life in the caput homogenates. Moderate levels of the enzyme were found in the cauda epididymis. Gamma-GT is histochemically detected from the 15th day of gestation in Wolffian ducts and in 17- to 18-day-old fetuses in newly differentiated epididymal tubules. Enzyme activity, was associated with the plasma membranes (apical, lateral, and basal), was preponderant on the apical part of the epithelial cells. During the first 15 days of the postnatal life, the histochemical reaction intensities were identical from the caput to the cauda epididymidis. From the 18th day onwards, enzyme activity decreased in the corpus and in the cauda, while gamma-GT increased in the caput epididymidis, and a strong activity was found on the apical surface of epithelial cells. Weak or moderate gamma-GT activity of spermatozoa in the caput tubules, increasing steadily from caput to cauda epididymidis, suggests that gamma-GT may be related to the functional maturation of spermatozoa.     

Loss of sperm surface sialic acid induces phagocytosis: an assay with a monoclonal antibody T21, which recognizes a 54K sialoglycoprotein

Using a monoclonal antibody T21, we reported that a mouse sperm maturation-associated antigen sialoglycoprotein of 54000 daltons (54K sialoglycoprotein) was secreted at the distal caput to proximal corpus epididymidis and that the 54K sialoglycoprotein had a hidden determinant (cryptodeterminant), which could be eliminated by sialidase treatment (Toshimori et al. (1988): Histochemistry 90:195-200; (1990a): Biol Reprod 42:151-160; (1990b): Arch Histol Cytol 53:339-349). This study evaluated the mouse sperm susceptibility to phagocytosis by macrophage in vitro. Comparisons were made between sperm from the caput epididymidis (caput sperm) incubated in modified Krebs Ringer's solution (MKR) and caput sperm incubated in MKR containing cauda fluid, and between sialylated (sialidase-untreated) sperm from the corpus and cauda epididymidis (corpus/cauda sperm) and desialylated (sialidase-treated) corpus/cauda sperm. The results showed that macrophages were least actively engaged in phagocytosis for caput sperm incubated in MKR containing cauda fluid, and most active for desialylated corpus/cauda sperm. Incubation of caput sperm in MKR containing cauda fluid revealed that the 54K sialoglycoprotein in cauda fluid could be bound to the flagellar surface of caput sperm. These results together with previous findings strongly suggest that the 54K sialoglycoprotein bound to immature sperm during maturation in the epididymis is implicated in the protection of sperm from phagocytosis with the aid of sialic acid residues.     

Segment-specific decrease of both catecholamine concentration and acetylcholinesterase activity are accompanied by nerve refinement in the rat cauda epididymis during sexual maturation

In the present work, histochemical and biochemical studies were conducted to analyze changes in the pattern of autonomic innervation during sexual maturation, using the rat epididymis as a model. Glyoxylic acid histochemistry and immunohistochemical studies against dopamine beta-hydroxylase (DbetaH) and acetylcholinesterase (AChE) indicated a reduction in the amount of catecholaminergic and AChE-positive neurons, fibers, and puncta detected in the cauda epididymis of adult rats (120 days old), when compared to immature (40 days) and young adult (60 days) animals. No obvious age-related variations were detected in the few catecholaminergic and AChE-positive fibers and puncta present in the caput region. AChE-positive fibers were found sorting out among epithelial cells and ending free upon the epithelial surface or into the tubular lumen of the cauda region of adult rats. Furthermore, a positive staining for AChE in epithelial cells was also detected in the caput and cauda epididymis in all ages studied. Biochemical analysis confirmed a significant decrease in noradrenaline concentration as well as AChE activity in the cauda epididymis with sexual maturation. Immunohistochemical studies against microtubule-associated protein 1B (MAP 1B), a neuronal cytoskeletal marker, further substantiated the quantitative changes observed in catecholaminergic and AChE-positive neuronal elements in the cauda epididymis. Thus, our results documented segment-specific variations in noradrenaline concentration and AChE activity during epididymal sexual maturation and suggest that such variations result, at least in part, from the refinement of the autonomic innervation pattern with age.     

Differential effect of hyperthyroidism on rat epididymal glycosidases

The impact of hyperthyroidism on epididymal glycosidases was studied in albino rats. Hyperthyroidism was induced in Wistar rats aged 30 days by daily injection of T4 (25 microg/100 g body weight/day intramuscularly) for 30 or 60 days; control rats were injected with vehicle (alkaline saline, pH 7.8). One set of hyperthyroid rats was reverted to euthyroid status by withdrawing T4 treatment after 30 days of hyperthyroidism. To asses the direct effect of thyroid hormone on epididymal hexosaminidases, caput, corpus and cauda tissues were stimulated with 25, 50 or 100 ng/mL T3 for 24 h, after an initial culture of 24 h. The activity of beta-glucosidase decreased in caput, corpus and cauda epididymis of hyperthyroid rats. beta-Galactosidase activity increased in the caput epididymis irrespective of the duration of hyperthyroidism. While a similar decrease occurred in the corpus and cauda epididymis in the 30 day hyperthyroid group, an opposite trend was observed in 60 day hyperthyroid rats. Caput beta-N-acetylglucosaminidase activities increased at both time points, whereas activity decreased in the corpus and cauda in 30 day, but increased in 60 day hyperthyroid rats. Hyperthyroidism consistently increased caput and corpus beta-N-acetylgalactosaminidase activity irrespective of the duration. Cauda epididymal beta-N-acetylgalactosaminidase activity was decreased in 30 day and increased in 60 day hyperthyroid rats. Hyperthyroidism induced changes in caput beta-galactosidase, beta-N-acetylgalactosaminidases, corpus beta-N-acetylglucosaminidase and cauda beta-N-acetylgalactosaminidase which were irreversible while the remaining actvities were brought back to normal when T4 treatment was withdrawn. In vitro studies showed that T3 stimulates epididymal hexosaminidases (beta-N-acetylglucosaminidase and beta-N-acetylgalactosaminidase) irrespective of the dose. These data suggest that thyroid hormones have a specific and direct influence on glycosidases in specific regions of the epididymis.     

Investigation of epididymal sperm maturation in the golden hamster

During passage of hamster spermatozoa through the epididymis their maturation is shown to involve changes in the sperm head, midpiece (mitochondria) and tail. The sum of these changes results in a dramatic increase in the fertilizing potential of the spermatozoa. When comparable numbers of spermatozoa from the caput or corpus epididymis were injected into one uterine horn of mature females, following ovulation induction, and spermatozoa from the cauda epididymis were injected into the contralateral horn, no fertilization was observed with caput epididymal spermatozoa, 1.7% of oocytes were fertilized by corpus epiddymal spermatozoa, whereas 79.5% fertilization was obtained with cauda epididymal spermatozoa. Total sperm numbers increased from caput to corpus to cauda [28.3 ± 12.2, 40.6 ±20.8, 1434 ±62 mihon, respectively]. The percentage of progressively motile spermatozoa increased from 27.9 ±6.4 to 33.8 ± 4.8 to 70 ± 10.7 during this passage. Viability, measured by exclusion of the dye, propidium iodide, was significantly less in spermatozoa from the cauda than from the proximal or mid-caput epididymis. The percentage of the live cells that were stained intensely by rhodamine-123 (a measure of mitochondrial membrane potential) increased during epididymal passage from 22.8 ±7.8% in the proximal caput epididymis to 57.2 ± 16.5% in the cauda epididymis. Staining with acridine orange (a measure of DNA packaging in the sperm head) indicated an increase in chromatin condensation in cauda epididymal spermatozoa, when compared to those obtained from the caput or corpus.     

大鼠精子在附睾成熟过程中肉毒碱量变化的研究

肉毒碱被认为是与精子在附睾中成熟有关的成熟因子。本文报告测定大鼠附睾头部,体部及尾部精子中的肉毒碱。结果表明精子在循附睾头、体、尾运行过程中,精子中肉毒碱含量逐步增加,在附睾体一头部,附睾尾一头部的精子内的肉毒碱量呈现十分显著性差异。结果提示附睾体部或体一头部交界部位可能是精子在附睾中成熟的关键部位。     

Regional variation in macrophage antigen expression by murine epididymal basal cells and their regulation by testicular factors

Factors controlling the appearance in the epididymis of basal cells and their expression of macrophage antigens were examined by ligating the efferent ducts to prevent the entry of spermatozoa in adult and juvenile mice. Fixation and antigen retrieval techniques were developed to preserve tissue morphology and expression of two macrophage antigens in paraffin-embedded epididymal tissue. A combination of periodate-lysine-phosphate fixation, low-temperature embedding and enzyme predigestion of sections permitted immunohistochemical detection of the mature macrophage antigen Mac-1, whereas the panmacrophage marker F4/80 required fixation in neutral-buffered formalin. Epididymal basal cells were immunostained for F4/80 and quantified with avidin-biotin-peroxidase. In the adult mouse, the total number of basal cells per millimeter length of tubule cross section perimeter and the percentage expressing the F4/80-antigen were significantly higher in the initial segment and caput region than in all other epididymal regions. In the initial segment, immunostained basal cells surrounded the tubule in a network, and some extended towards the lumen. Ligation of the efferent ducts to prevent inflow of testicular secretions significantly reduced the number of basal cells per cross section in the initial segment of the adult and juvenile; the percentage of basal cells expressing macrophage antigens in the initial segment and the caput epididymidis was also reduced. Since basal cells still appeared in the ligated postpubertal epididymis, it is concluded that testicular exocrine secretions entering the epididymal lumen around puberty are not the major influence on basal cell appearance in the murine epididymis, but they may modulate their expression of macrophage antigens.     

Erratum

During passage of hamster spermatozoa through the epididymis their maturation is shown to involve changes in the sperm head, midpiece (mitochondria) and tail. The sum of these changes results in a dramatic increase in the fertilizing potential of the spermatozoa. When comparable numbers of spermatozoa from the caput or corpus epididymis were injected into one uterine horn of mature females, following ovulation induction, and spermatozoa from the cauda epididymis were injected into the contralateral horn, no fertilization was observed with caput epididymal spermatozoa, 1.7% of oocytes were fertilized by corpus epididymal spermatozoa, whereas 79.5% fertilization was obtained with cauda epididymal spermatozoa. Total sperm numbers increased from caput to corpus to cauda [28.3 ± 12.2, 40.6 ± 20.8, 144 ± 62 million, respectively]. The percentage of progressively motile spermatozoa increased from 27.9 ± 6.4 to 33.8 ± 4.8 to 70 ± 10.7 during this passage. Viability, measured by exclusion of the dye, propidium iodide, was significantly less in spermatozoa from the cauda than from the proximal or mid-caput epididymis. The percentage of the live cells that were stained intensely by rhodamine-123 (a measure of mitochondria1 membrane potential) increased during epididymal passage from 22.8 ± 7.8% in the proximal caput epididymis to 57.2 ± 16.5% in the cauda epididymis. Staining with acridine orange (a measure of DNA packaging in the sperm head) indicated an increase in chromatin condensation in cauda epididymal spermatozoa, when compared to those obtained from the caput or corpus.     

Secretion of glycosidases in human epididymal cell cultures

The dynamics of glycosidase secretion was evaluated in human epididymal cell culture. Epithelial cells from caput, corpus, and cauda epididymis were isolated from tissue obtained from patients undergoing therapeutic orchidectomy due to prostatic carcinoma. The activities of alpha-glucosidase, N-acetylglucosaminidase, beta-glucuronidase, and alpha-mannosidase were analyzed in conditioned culture media. Glycosidase activity was significantly higher in corpus and/or cauda than in caput epididymis. There was a time-dependent increase in enzyme activities that was maximal between 10 and 14 days of culture in all epididymal regions. Epididymal glycosidases are secreted by cultured epithelial cell from human epididymis with an increase toward the distal regions of this organ, which may be related to the dynamics of sperm maturation. Cultures from different epididymal regions may represent a valuable tool to study of human epididymal function.     

Changes in the number, proliferation rates, and bcl-2 protein immunoexpression of epithelial and periductal cells from rat epididymis during postnatal development

To investigate 1) the correlation between the proliferative activity of epididymal epithelium plus myoid cells and the increase in the number of these cells and 2) the role of the basal epithelial cells in the renewal of epididymal epithelium, a quantitative evaluation of the proliferation of both epithelial cells and periductal myoid cells in the different epididymal regions (caput, corpus, and cauda) has been carried out during postnatal development of the rat by immunohistochemical evaluation of BrdU-labeling indices. These data were correlated with cell numbers and counted by the optical dissector method. The presence of bcl-2 protein was immunohistochemically detected and evaluated. No significant differences in BrdU indices were observed among epididymal regions in any stage studied. Cell proliferation decreased from the prepubertal period to adulthood in both epithelial and myoid cells in the three regions of the epididymis, suggesting a close relationship between epithelial and mesenchymal components. The numbers of both cell types were significantly higher in the caput than in the corpus and cauda in all stages studied, suggesting functional differences between regions. A negative linear correlation between proliferative activity and cell numbers was noted that might be related to regulation of the cell population size. Basal cells showed a lower proliferation rate than principal cells, but most of the immunoreactive bcl-2 protein, in pubertal and adult epididymides, was observed in basal cells. Therefore, these cells might comprise a low-proliferating and apoptosis-resistant population.     

Localization of androgen and estrogen receptors in adult male mouse reproductive tract

There is considerable variation, both within and between species, in reports of nuclear steroid receptor localizations in the male reproductive tract. In this study, androgen receptor (AR) and estrogen receptors ERalpha and ERbeta were visualized by immunohistochemistry in adult male mice reproductive tracts, including testes, efferent ductules; initial segment, caput, corpus, and cauda epididymides; and vas deferens. Antibody specificity was demonstrated by Western blot and antibody competition. In testis, AR was expressed in Leydig cells, Sertoli cells, and most peritubular cells, but not in germ cells; Sertoli cells showed more intense staining in stages VI-VII; ERalpha was present in Leydig and some peritubular cells; ERbeta was in Leydig, some peritubular, all Sertoli and germ cells except in spermatids and meiotic spermatocytes. In efferent ductules, AR was strongly expressed in ciliated and nonciliated epithelial cells and in stromal cells; ERalpha was strongly expressed in ciliated and nonciliated epithelial cells; stromal cells were negative; and ERbeta was strongly expressed in ciliated and nonciliated epithelial cells and also in stromal cells. In epididymis, AR was strongly expressed in all epithelial cells (not in intraepithelial lymphocytes); ERalpha was strongly expressed in apical, narrow, and some basal cells of the initial segment, and in caput, principal cells of the caput, clear cells of the distal caput through cauda; stromal cells were negative in the initial segment, but more stromal cells were stained from caput to cauda; ERbeta was strongly expressed in most of epithelial cells of the epididymis, but stromal cells were inconsistently stained. In vas deferens, AR was weakly expressed or absent in principal cells but moderately stained in basal cells, smooth muscle cells of stroma were stained intensely, ERalpha was absent in epithelial cells but present in a subepithelial smooth muscle layer, and ERbeta was strongly expressed in all epithelial cells and most stromal cells. This study demonstrates that the reproductive tracts of male mice differ considerably from those of rats in expression of ARs and ERs and that caution is needed when extrapolating nuclear steroid receptor data across mammalian species.     

Effect of gossypol on the concentration of sodium and potassium in the rat epididymis

The effects of administration of gossypol acetic acid (7.5 mg/kg daily for 4 weeks) on the concentration of Na+ and K+ in the rat epididymis was assessed. Epididymal fluid samples, collected by micropuncture, from the caput, corpus, proximal cauda and distal cauda epididymis from gossypol-treated and control animals were analysed for Na+ and K+ concentrations. Gossypol-treated males failed to impregnate healthy females, presumably because their sperm were immotile. In gossypol-treated rats, Na+ levels decreased significantly (P less than 0.01) in the caput, corpus, proximal and distal cauda epididymis. In contrast, the K+ concentration was increased significantly (P less than 0.05) only in the caput and corpus epididymis. This altered electrolyte milieu may be responsible, to some extent, for immotility and hence infertility.     

OCTN2在1例正常生育男性附睾中的表达报告

目的：研究人类附罩有机阳离子转运子2COCTN2）的mRNA表达特征及蛋白表达特征,为进一步探讨附睾肉碱转运机制提供理论依据。方法：采用RT-PCR方法检测人类附睾组织头部、体部及尾部OCTN2基因的表达;并用Westernblot方法检测该基因在附睾中的蛋白表达,计算其在蛋白水平的相对表达量。结果：OC-TN2mRNA在人附睾头、体、尾组织中均有OCTN2表达,表现为附睾头部表达较弱,而附睾体、尾部分表达丰富;OCTN2蛋白在人附睾头部表达较弱,表达量为（0．71±0．09）,附睾体、尾部分表达较丰富,表达量分别为（0．95±0．22）与（0．99±0．15）。结论：两种方法均证实有机阳离子转运子2在人类附睾中有表达,且呈现附睾头部表达较弱,附睾体、尾部分表达卡富的特,止,为进一步研究附睾肉碱转运机制奠定基础。     

Purification and Localization of Acidic Epididymal Glycoprotein (AEG): A Sperm Coating Protein Secreted by the Rat Epididymis

A protein designated acidic epididymal glycoprotein (AEG) was purified from rat epididymis using ion exchange chromatography on DEAE-Sephadex, gel filtration in Sephadex G-75 and affinity chromatography on Concanavalin-A Sepharose. AEG is a major secretory product of the epididymis making up 2–3 per cent of total soluble protein. Antibody to AEG was raised in rabbits and purified by affinity chromatography on AEG-Sepharose. Quantitation of AEG in cytosol using "rocket" immunoelectrophoresis showed AEG to increase in epididymal segments from caput to cauda. Ligation of the midcorpus decreased AEG in the cauda. Localization of AEG using an immunoperoxidase method revealed that it is secreted largely by the epithelium of caput and corpus beginning with the region distal to the initial segment. It appears to be secreted by a specific cell type, probably the so-called "principal" cell. Specific staining of AEG was also noted in "clear" cells in the cauda. Spermatozoa become coated with AEG as they leave the initial segment and remain so during passage through the cauda.     

γ-Glutamyl transpeptidase in rat epididymis: effects of castration, hemicastration and efferent duct ligation

Gamma-Glutamyl transpeptidase (gamma-GT) was studied histochemically and biochemically in the rat epididymis after castration with or without testosterone treatment, or after hemicastration and ligation of the efferent ducts. There was a strong reaction to gamma-GT in the apical part of the epithelium in the caput epididymis, while in the corpus and cauda the reaction was confined mainly to the luminal contents. Castration caused a marked decline in epithelial gamma-GT activity within 10 days. Subsequent testosterone treatment (1 mg/day for 10 days) restored gamma-GT activity in the apical surface and lumen. After hemicastration of adult rats, and after hemicastration or ligation of the efferent ducts in immature 28-day-old rats, a small but significant (P less than 0.001) decrease was observed in gamma-GT activity in the epididymal caput compared to controls. The quantities of six other enzymes (beta-N-acetylglucosaminidase, beta-galactosidase, angiotensin-converting enzyme, alanyl amino-peptidase, dipeptidyl peptidase IV, acid phosphatase) also displayed significant changes after castration and restoration of activities by testosterone treatment. However, their distribution in the caput and cauda epididymis was more even than that of gamma-GT, and the changes after castration were less drastic. It is concluded that gamma-GT is a highly sensitive androgen-dependent secretory marker in the caput epididymis and may have an important function in sperm maturation.     

Sperm number and condition affect the number of basal cells and their expression of macrophage antigen in the murine epididymis

Unilateral ligation of the mid-corpus epididymis, the proximal vas deferens and imposition of an abdominal temperature for 6 days as well as bilateral castration for 3, 6 or 14 days, resulted in a change in epithelial composition of the adult murine epididymis with regard to the number and antigen expression of basal cells. There were fewer basal cells per tubule cross-section with fewer expressing F4/80 antigen when spermatozoa were absent from the proximal lumen following short-term castration. Conversely, more basal cells with more of them demonstrating macrophage antigen expression were evident when more or damaged spermatozoa were in the proximal lumen after corpus ligation and exposure to abdominal temperature or in the cauda after long-term withdrawal of androgen support. By contrast, ligation of the vas deferens did not lead to tubule distension, and hence sperm accumulation, and did not alter the basal cell population in the cauda epididymis. The data suggest that epididymal basal cells respond in number and macrophage antigen expression to the presence of sperm autoantigens in the lumen with little dependence on circulating androgens. These changes may represent responses to minimise the interaction of sperm autoantigens with the immune system and the risk of immunological infertility.     

Postnatal changes in the expression of claudin-11 in the testes and excurrent ducts of the domestic rabbit (Oryctolagus cuniculus domesticus)

We examined the expression of claudin-11 (CLDN11) in the testes and male reproductive tracts of rabbits. The rabbit CLDN11 cDNA sequences were nearly identical with human, mouse, and bovine CLDN11. The levels of CLDN11 mRNA and protein (22 kDa) were markedly increased in the testis during adult development. On postnatal day (PND) 10, CLDN11 was colocalized with ZO-1 at the lateral contacts between adjacent Sertoli cells and was perpendicular to the basal lamina. In adult testis on PND 180, CLDN11 was codistributed with ZO1, and the pattern of immunoreactivity consisted of wavy linear tracts parallel to the basal lamina, which was different according to the spermatogenic stage. These results suggest that CLDN11 participates in inter-Sertoli cell tight junctions (TJs) at the blood-testis barrier in adult rabbits. CLDN11 was also found in the basal regions of Sertoli cells adjacent to the basal lamina in adult testis, suggesting that CLDN11 also participates in the adhesion between Sertoli cells and the basal lamina. CLDN11 mRNA and protein expressions were decreased in the adult epididymis compared with those in immature animals. In adults, CLDN11 mRNA levels were relatively high in the efferent duct, followed by those in the vas deferens, proximal corpus, and distal cauda, although low levels were observed in the initial segment and caput. On PND 10, CLDN11 immunoreactivity was identified at the apicolateral contacts between adjacent epithelial cells in the epididymis and vas deferens. In adults, CLDN11 was found in the nonciliated cells in the efferent duct and at the lateral contacts in the epithelial cells in the epididymal segments. In the caput, CLDN11 was found at the apicolateral contacts between adjacent epithelial cells, but expression was weak to negligible in the corpus of the vas deferens. CLDN11 may play an important role in TJs and cell adhesion in immature rabbit excurrent duct epithelia. In adult rabbits, CLDN11 in efferent duct epithelium and epididymal epithelium may contribute to the specific environment for sperm maturation.