Ultrastructural differences in efferent ducts and several regions of the epididymis of the hamster

Distribution of the Novel RFRP-3/receptors system in the epididymis of the seasonal desert rodent, Gerbillus tarabuli, during sexual activity

RFamide-related peptide (RFRP-3), the Mammalian ortholog of the Avian gonadotropin-inhibitory hormone (GnIH), is a novel neuropeptide known for its inhibitory regulatory effect on reproduction in various mammalian species. However, a stimulatory action has been reported. This paper aims to: i) study the histology of the epididymis (caput) of Gerbillus tarabuli during the breeding period; and ii) to determine the distribution of the "RFRP-3/receptors system" in the epididymis (caput) of this desert rodent during the active season, and thus, to inspect its potential local interfering in sperm maturation. For that, immunohistochemistry was performed to detect the epididymal immunolocalizations of the three molecules, RFRP-3, GPR147, and GPR74. This is the first report of the epididymis histology in Gerbillus tarabuli, as it is the first evidence of the existence of the RFRP-3/Receptor system in the same organ of the same species. During the breeding season, moderate immunostaining of the RFRP-3/receptors system was present in the caput epididymis' epithelial parts (basal and principal cells) and spermatozoa. In contrast, these three molecules were absent in the peritubular and muscle coat's myoid cells and of the interstitial part of the caput epididymis. The results suggest that the epididymis is a potential source of RFRP-3 in the desert Rodent, Gerbillus tarabuli, which may function as a paracrine and/or autocrine factor affecting the main epididymis' function: sperm maturation.

Epididymis of Viscacha (Lagostomus maximus maximus): A Morphological Comparative Study in Relation to Sexual Maturity

The morphological variations and the androgen receptor (AR) expression were studied in viscacha epididymis in relation to sexual maturity. The animals were divided into immature, pre-pubertal and adult, according to their corporal weight and testicular histology. The epididymides were studied by light microscopy, immunohistochemistry for AR and morphometric analysis. In pre-pubertal and adult animals, four well-differentiated segments (initial, caput, corpus and cauda) were observed, while in immature animals, three segments were identified (initial-caput segment, corpus and cauda). In each segment, the structural parameters and the relative cell distribution were different between the groups. The serum testosterone levels of pre-pubertal and adults showed a very significant increase related to sexual maturity. The AR expression in epithelial and fibromuscular stromal cells was different between the groups. In conclusion, the present work demonstrates that the morphological characteristics of the viscacha epididymis vary while sexual maturity is reached, the development of initial and caput is subsequent to corpus and cauda development and the androgens might play an important role during this process.

Ductuli efferentes of the male Golden Syrian hamster reproductive tract

Efferent ductules are responsible for the transportation of spermatozoa from the testis to the epididymis and their epithelium is responsible for the reabsorption of over 90% of the luminal fluid. The purpose of this research was to characterize the gross morphology and histology of efferent ductules in the male Golden Syrian hamster. The efferent ductules emerge from rete testis with a unique polarity at the apex or cephalic pole of the testis. The number of efferent ductules varied from 3 to 10 with an average of 6.0 and blind ending ducts were observed in approximately 56% of the males. The ductules merged into a single common duct prior to entering the caput epididymidis. The proximal efferent ductule lumen was wider than the distal (conus and common ducts), consistent with reabsorption of most of the luminal fluid, as was morphology of the ductal epithelium. Non-ciliated cells in the proximal region had prominent endocytic apparatuses, showing both coated pits and apical tubules in the apical cytoplasm. Large basolateral, intercellular spaces were also present in the epithelium of the proximal region. Distal non-ciliated cells had an abundance of large endosomes and lysosomal granules. Localisation of sodium/hydrogen exchanger-3 (NHE3; SLC9A3) and aquaporins 1 and 9 (AQP1, AQP9) along the microvillus border was also consistent with ion transport and fluid reabsorption by this epithelium. In comparison, the caput epididymidis epithelium expressed only AQP9 immunostaining. Another unusual feature of the hamster efferent ductules was the presence of glycogen aggregates in the basal cytoplasm of small groups of epithelial cells, but only in the proximal ducts near the rete testis. Androgen (AR), estrogen (ESR1 and ESR2) and vitamin D receptors (VDR) were also abundant in epithelial nuclei of proximal and distal efferent ductules. In comparison, caput epididymidis showed very little immunostaining for ESR1.

Ultrastructure of the epithelium lining of cauda epididymidis in mongrel dogs

The epithelium lining of cauda epididymidis in mongrel dogs was examined by transmission electron microscopy. The epididymal epithelium is pseudostratified with stereocilia and is composed predominantly of principal and clear cells. Therefore, exist basal and apical cells. The principal and clear cells show features suggesting that they may be preferentially involved in absorptive and secretive functions. These results are compared with previously published data on the cauda epididymidis of other mammalian species, in order to understand the significance of the epididymis in sperm maturation.

Comparative morphometric and glycohistochemical studies on the epididymal duct in the donkey (Equus asinus) and dromedary camel (Camelus dromedarius)

The present study was undertaken to compare morphometric and glycohistochemical differences in the epididymal duct of the donkey and the dromedary camel. Paraffin-embedded sections from the different regions of the duct (caput, corpus and cauda) of both species were stained conventionally for general histology and histomorphometry and also with fluorescein isothiocyanate (FITC) conjugated lectins for glycohistochemical mapping. Morphometric data (means ± SE) showed that the luminal diameter was widest (1029.76 ± 15.04 μm) in the donkey cauda and narrowest (179.80 ± 3.27 μm) in the camel corpus. The thickness of the peritubular muscle coat had the highest (74.32 ± 1.85 μm) and the lowest (24.32 ± 0.74 μm) values in the donkey cauda and corpus respectively. The greatest (94.44 ± 2.08 μm) and the least (21.48 ± 0.66 μm) values of epithelial height were reported respectively in the camel caput and in the donkey cauda. The length of stereocilia of principal cells in the camel was greatest (21.88 ± 0.57 μm) and lowest (6.68 ± 0.28 μm) in the caput and cauda. Binding sites for only six out of eight lectins could be found. The distribution pattern of binding sites of different lectins showed significant variations in both a species-specific and also region-specific manner. Distinct labeling was found in the Golgi zone, apical cytoplasm and on stereocilia of principal cells in the camel (WGA and DBA) and donkey (DBA) caput region, while other lectins exhibited variable reactivity in the other regions in both species. The basal cells showed variable binding to most of the lectins, however, they displayed distinct binding to WGA and PSA throughout the duct in camel and donkey respectively. In conclusion, both morphometric and glycohistochemical findings displayed regional species-specific and potentially functional relevant characteristics.

Histological and immunohistochemical studies on the epididymal duct in the dromedary camel (Camelus dromedarius)

This study was conducted to underscore the spatial distribution of some biologically active proteins within the epididymal duct in the dromedary camel. Paraffin-embedded sections from different regions of epididymis were stained by conventional histological techniques and by immunohistochemistry. A battery of primary antibodies against six proteins (S100, alpha smooth muscle actin [α-SMA], connexin-43 [Cx43], galactosyltransferase [GalTase], angiotensin converting enzyme [ACE], and vascular endothelial growth factor [VEGF]) were used. The epididymal epithelium consisted of five cell populations: principal, basal, apical, dark, and halo cells. The histochemical findings indicated the absence of binding sites for VEGF and Cx43. The principal cells (PCs) showed variable immunoreactivity (IR) for ACE, S100, and GalTase throughout the whole length of the duct. The apical surfaces of most PCs (at the caput) and some PCs (at the corpus) exhibited intense ACE-IR, whereas those at the cauda displayed alternating negative and strong immunostaining. Similarly, moderate S100-IR was found in cytoplasm and nuclei of all PCs at the caput, few PCs at the corpus, and several PCs alternating with negative PCs at the cauda. In contrast, only some PCs showed weak to strong GalTase-IR in different regions. Apart from negative to weak positive S100-IR, basal cells failed to show IR for all other proteins. Apical cells displayed strong IR for ACE, S100, and GalTase with some regional differences. The peritubular and vascular smooth muscle cells revealed strong α-SMA-IR in all regions. In conclusion, the spatial distribution of different proteins in camel epididymis showed similarities and differences to other mammalian species. The region-specific topographic distribution of different proteins and cell types might indicate that the caput and cauda are metabolically more active than that of the corpus.

A light and scanning electron microscopic study of the epididymis active state of the endemic Mexican rodent Peromyscus winkelmanni (Carleton) (Rodentia: Muridae)

The macroscopic and microscopic anatomy of the epididymis of the sexually mature Peromyscus winkelmanni (carleton) was examined using light and scanning electron microscopy. The epididymis was divided into three regions: caput, corpus and cauda. The epididymal duct was lined with columnar and cubic epithelium with stereocilia and covered by a muscular connective tissue sheath. Capillaries appear to penetrate directly into the epithelium from the underlying connective tissue in the initial segment. The epididymal epithelium presents four cell types: principal, basal, apical and clear cells. Based on morphological differences (height of epithelial cells, length of the stereocilia, luminal area, larger diameter and spermatic index), the epididymis of P. winkelmanni, presents seven zones. The stereocilia of the epididymal ducts of zones I, II, IV and V are thick and tall, while in zone III they are thin and short. The stereocilia in zone VI are thin, while in zone VII they are short but thick. The secretory products observed in the lumen of the epididymal ducts have vesicular, granular and fibrous form in the seven zones. This study contributes to an understanding of the morphofunctional features of the epididymis in sperm maturation in a species that shows seasonal reproductive activity.

Morphological features of the epididymal epithelium of gerbil, Meriones unguiculatus

Principal cells of the ducts epididymis of the Mongolian gerbil showed ultrastructural characteristics of lining epithelium cells close related to processes of protein secretion, and transcytosis occurring between adjacent principal cells which were mainly verified in the initial segment. Principal cells also presented roles of fluid phase and adsorptive endocytoses, as well as autophagic and heterophagic lysosomal activities mainly observed in the caput epididymis. Columnar (principal) cells of the corpus epididymidis presented great number of variable vesicles and vacuoles distributed in all the cytoplasmic levels occurring a progressive coalescence pattern among them, which help to guarantee formation of cytoplasmic channels for fluid phase transport between the tubular lumen and epididymal interstitium. Clear cells were presented in the initial segment and predominately in the cauda epididymis epithelium of the gerbil and showed marked ultrastructural characteristics of endocytosis activities occurrence, perhaps directly related to the turnover of fluid phase of spermatozoa stored into the lumen of the distal tail. Other epididymal epithelium cells were verified and described such as basal, halo, apical and dark cells, but they did not presented special ultrastructural features.

Epididymis of viscacha (Lagostomus maximus maximus): morphological changes during the annual reproductive cycle

Little is known about morphological changes in the epididymis in relation to the natural photoperiod or their influence on sperm maturation. The viscacha is a seasonal rodent living in the Southern Hemisphere. The adult males exhibit an annual reproductive cycle with periods of maximum gonadal activity and gonadal regression. In this work, we studied seasonal variations in the morphology and cellular population of the epididymis during both periods, and we compared these results with those recorded at the testicular level. Epididymides were removed and studied by light microscopy. Measurements of luminal diameter, epithelial height, thickness of the lamina propria, and relative cellular distribution were performed. Analysis of variance (ANOVA) or nonparametric ANOVA was used to compare the results. Striking quantitative and qualitative changes were observed. Epididymides in periods of gonadal regression showed a significant decrease in luminal diameter and epithelial height in cauda, while the thickness of the lamina propria increased. In the epididymal corpus, the number of clear cells increased, and the cytoplasm of principal cells showed numerous giant vacuoles. During the active period, the number of halo cells increased and the cytoplasm of these cells was filled with dense bodies. In conclusion, the epididymis of the viscacha exhibits important seasonal morphological changes throughout annual reproductive cycle. The epididymal corpus and cauda segments appeared to be the segments most sensitive to seasonal cyclical variations of the external environment. We therefore postulate that the epididymal morphology of the viscacha probably could be regulated by the natural photoperiod.

Overview of male reproductive pathology

An understanding of form and function is important for examination of the male reproductive tract. A basic understanding of spermatogenesis and hormonal function in the reproductive tract is essential for the pathologists in this evaluation. Gross and histologic reproductive changes need to be distinguished from normal variation and correlated with the reproductive status of the animal. This is especially important when correlating histologic changes with organ weight and other reproductive parameters, such as seminal analysis data. Sexual maturity of animals and tissue handing can impact interpretation. Sexual immaturity of preclinical safety animals can present challenges for accurate identification of compound-related changes. Likewise, proper handling of unfixed reproductive tissues and appropriate selection of a fixation protocol are important in avoiding artifacts that may interfere with the microscopic evaluation. The histopathology technician needs to recognize testicular landmarks that allow for correct orientation at trimming so the pathologist can assess not only the morphology of seminiferous tubules but also the outflow tract. For the most effective evaluation of the male reproductive tract, the testes and epididymides should be examined concurrently. Although the term "staging" is often used inappropriately, the pathologist should review testicular tissues in a "stage-aware" manner. This article reviews gross and histologic changes of the male reproductive tract as well as tissue orientation and fixation to assist in accurate interpretation of potential treatment-related changes in male reproduction.

Age-related changes in the hamster epididymis

Reproductive ability is decreased in aged animals and in men. Little is known about the changes taking place in the epididymis, and the possible influence on the loss of sperm quality. We studied the age-related alterations in the epididymis and in epididymal spermatozoa of hamsters. Adult (6-month-old), middle-aged (18-month-old), and aged (24-month-old) hamsters were used. Serum samples were obtained to determine testosterone levels. Testes and epididymides were removed and studied by light and electron microscopy. Epididymal sperm was also obtained and the motility, position of cytoplasmic droplet, and concentration were evaluated. Measurements of the height of the epithelium, length of stereocilia, external tubular diameter, and thickness of the muscular wall were performed. The proliferative activity was also studied. An ANOVA analysis was used to compare quantitative differences between epididymal zones and age groups. Aged hamsters presented involutive changes in the epididymis. A decrease in tubular diameter was found in cauda; principal cell ultrastructure showed changes including the appearance of damaged mitochondria, bundles of filaments, and the accumulation of lipofuscin. Some clear cells showed an unusual morphology by the presence of large electrondense vacuoles. A reduction in sperm quality was also observed, including a decrease in sperm motility and concentration, and alterations in the migration of sperm cytoplasmic droplet. Testosterone levels and cellular proliferative activity did not change. Aging causes a morphological alteration of hamster epididymis (mainly in the cauda), and a decrease in sperm quality.

Histological and immunohistochemical study of the cat epididymis

A histological and immunohistochemical study of the epididymis of 21 cats which ranged from 7 to 8 months to 2 years of age was made. Five different cell types were observed in the feline epididymis: principal and basal cells, which were the most numerous, apical and narrow, PAS positive cells, which were scarce, and migratory cells, consisting of lymphocytes and macrophages. Four morphologically distinct areas of the cat epididymis were identified. Region I displayed a stellate lumen and the principal cells were tall and presented long and irregular stereocilia. In region II, the lumen was oval and the principal cells were shorter than in the initial area. Region III displayed characteristics similar to those of region I; the principal difference was the presence of short and regular stereocilia on the surface of the principal cells. In region IV the lumen was very spacious and the epithelium shorter than in the other regions. In regions I, II, and III intraepithelial cavities were observed. With regard to the immunohistochemical results, the basal cells displayed medium immunoreactivity with vimentin. Due to its anti-desmin reactivity, the muscle wall which surrounds the epididymis was seen to become progressively thicker as it nears the tail. Broad-spectrum anti-cytokeratin serum produced intense immunostaining in the basal, apical and narrow, PAS positive cells; the principal cells of region IV also displayed a strong immunoreactivity.

Morphological and histochemical changes in the epididymis of hamsters (Mesocricetus auratus) subjected to short photoperiod

The morphological involution and histochemical changes of the Syrian hamster (Mesocricetus auratus) epididymis induced by a short light period were investigated. Under short-day conditions, the epididymis showed marked morphological changes including a decrease in luminal diameter, disappearance of spermatozoa, increase of interductal tissue, increase of intraepithelial lipofuscin deposits, the presence of phagolysosomes in the principal cells and macrophage-like cells, and a considerable modification of most clear cells. With lectin histochemistry changes were found in the glycoconjugates of principal cells of the regressed epididymis, either a decrease (PNA, WGA, HPA and DBA) or an increase (MAA) in the affinity of lectins to the Golgi area, or a decrease (HPA) or an increase (PNA) in lectin binding to stereocilia. Both morphological and histochemical results showed that, under this light condition, the cauda epididymidis presented the most prominent alterations, and that the epididymis showed increased absorptive activity and a decreased synthesis of glycoproteins. All these changes are probably due to the decrease in testosterone levels.

The apical mitochondria-rich cells of the mammalian epididymis

The morphology and function of the apical mitochondria-rich cells in the mammalian ductus epididymidis epithelium are revised. These cells are similar in all mammalian species studied. Apical mitochondria-rich cells are scarce (1-5 cells/100 principal cells) and are mainly found in the initial epididymal segments. Their morphology varies from slender cells that extend from the basal lamina to the epididymal lumen, to round cells that protrude into the lumen and are not in contact with the basal lamina. Their cytoplasm is more electron-dense than that of principal cells and contains more mitochondria which, in some species, are surrounded by rough endoplasmic reticulum cisternae. The adluminal cytoplasm displays a few short microvilli and contains many acid phosphatase positive vesicles. Apical mitochondria-rich cells differ from the principal cells in some histochemical features such as: (a) different lectin-staining pattern; (b) more intense reaction to the enzymatic activities: carbonic anhydrase, Ca(2+)-ATPase, peanut-agglutinin-sialidase, NADP dehydrogenase, succinate dehydrogenase, alpha-galactosidase and beta-galactosidase; (c) more intense immunoreaction to several cytokeratin types and to estradiol-related receptor protein; (d) weaker immunoreaction to epithelial membrane antigen and to retinol-binding protein. Although the function of the apical mitochondria-rich cells is still unknown, the following possible functions have been suggested: holocrine secretion; cooperation with the principal cells in epididymal reabsorption of testicular fluid; and acidification of epididymal fluid. Experimental results suggest that differentiation and maintenance of apical mitochondria-rich cells are not under androgen control and that these cells are sensitive to estrogen stimulation.

Ultrastructure of epididymal epithelium in Equus caballus

The ultrastructure of the epithelial lining of the ductuli efferents and the ductus epididymis in the horse (Equus caballus) is described. Several types of cells can be distinguished: ciliated and non-ciliated cells make up the epithelium of the ductuli efferents, whereas principal, apical and basal cells are found in the ductus epididymis. The observations are compared with those made in other species, in particular in the donkey (Equus asinus), and the possible functional roles of the different cell types are discussed.

Localization and activity of Na+,K(+)-ATPase in the ductuli efferentes of the rat

The Na+,K(+)-ATPase enzyme through its p-nitrophenyl phosphatase activity was localized in the ductuli efferentes of rats. Enzymatic activity was demonstrated along the cytoplasmic side of the plasmalemma of the ductular epithelial cells. The most intense deposition of reaction products was found on the plasmalemma delimiting the lower lateral and basal regions of the cells. The plasma membranes forming the microvilli, apical junctional complexes were devoid of reaction product while the midlateral membranes showed a weak reaction. The enzyme reaction was potassium-dependent and was abolished by addition of 10 mM ouabain to the incubation media. Enzyme activity decreased significantly from proximal to distal regions of the ductules (8,101.47 +/- 274.53, 6,658.95 +/- 269.53 and 4,668.10 +/- 575.41 pmoles p-nitrophenol/mm/h, respectively in initial, conus vasculosus and terminal zones). A unified model for water absorption is proposed in the efferent ductules based upon this data and that of others.

Occurrence of bioactive and immunoreactive inhibin (13 KD) in human epididymis

Using specific polyclonal antibodies generated against a 13 KD human testicular inhibin, immunocytochemical localization of inhibin was carried out in different regions of human epididymis. The concentrations of inhibin were greater in caput and corpus regions as compared to the caudal region. The epididymal inhibin was found to be bioactive, since it suppressed specifically the FSH levels of rat pituitaries in vitro. Spermiophage/macrophage cells exhibited strong staining for inhibin which were suggestive of a possible role of inhibin in modulation of immune function. In view of the known activities of inhibin in cellular growth, differentiation, and steroidogenesis, epididymal inhibin could have a role in acquisition of sperm fertilizing capabilities.

[Spatial pattern and microvascularization of the ductuli efferentes testis of bulls (Bos taurus)]

The arrangement, origin, course and opening of the ductuli efferents testis of the bull (Bos taurus) were visualized using scanning electron microscopy. The corresponding capillary structure was also described and documented with the help of corrosive microanatomical casts. The number of the ductuli efferents testis of the bull varies narrowly between 12 to 13. Ductuli removed from the surrounding tissue have a length of up to 78 cm. The duct system is composed of linear as well as tortuous parts, permitting division into three distinct segments. Blind ending ductules are very short. We therefore do not see these structures as being associated with spermiostasis. The capillary density as well as the capillary architecture show regional peculiarities. All segments of the ductuli efferents testis are composed of capillaries of the continuous type. The findings indicate that the increased capillary density in the voluminous initial section of the ductuli efferents testis represents the basis for resorptive as well as secretory activities in the bull.

Regional differences in the morphology of the goat epididymis: a light microscopic and ultrastructural study

The goat epididymis, based on morphological differences, was divided into five regions; regions I and II, and the proximal part of region III constituted the head; the distal part of region III and region IV, the body; and region V, the tail. The epithelium of all regions contained principal and basal epithelial cells and intraepithelial lymphocytes and macrophages. In addition, regions II to IV also contained a few apical cells. Clear cells were absent. The epithelium varied in height from the tallest in region I (88 +/- 33 microns) to the shortest in region V (38 +/- 5 microns). Conversely, the luminal diameter, thickness of smooth muscle wall, and luminal sperm concentration were highest in region V. The irregular epithelial height of regions I and IV accounted for a stellate lumen in contrast to the oval lumen of the other regions. Whereas the lumen of region I contained only a few sperm, those of regions II, III, and IV were filled with sperm. Principal cells were the only cell type that showed striking cytological differences between regions. While they contained absorptive features (canaliculi, pinocytotic and coated vesicles, and subapical vacuoles) in all regions, the principal cells of region II were filled with large, heterogeneous vacuoles (up to 5 microns in diameter), suggesting that they may be preferentially involved in transporting and digesting particulate material. Besides absorptive features, principal cells of all regions contained morphological correlates of protein synthesis such as highly developed Golgi complexes in the supranuclear area and numerous cisternae of RER near the Golgi body and in the infranuclear cytoplasm. The cisternae of RER were more developed in region IV, and in some instances, they were distended with flocculent material resembling newly synthesized protein. Unlike the protein synthesizing organelles, principal cells of all regions lacked morphological correlates of steroid hormone synthesis. These results are compared with previously published data on the regional differences in the epididymis of other species, especially with those of the rat and the bull, in an effort to understand the significance of the epididymis in sperm maturation.

Duration of epididymal sperm transit in hamster: an autoradiographic study

The time required for passage of spermatozoa through the epididymis has been determined in hamster employing quantitative light microscopic autoradiography with 3H-thymidine. The time required for spermatozoa to traverse the caput is 3 days; corpus, 2 days; proximal cauda, 2 days; distal cauda, 6 days. An additional 2 days are required for passage of spermatozoa through the proximal ductus deferens. The total duration of sperm transit through the ductus epididymis in sexually rested hamster has been estimated at about 15.0 days.

Immunocytochemical localization of the major glycoprotein of epididymal fluid from the cauda in the epithelium of the mouse epididymis

The most abundant protein in fluid from the mouse cauda epididymidis, designated CP 27, is a glycoprotein that migrates at approximately 27000 daltons on SDS-polyacrylamide gels. Samples of CP 27 were isolated by preparative gel electrophoresis and were used to raise a guinea-pig polyclonal antiserum, which reacted with a single band on western blots of caudal epididymal fluid. This antiserum was used for immunocytochemical localization of CP 27 in histological sections of mouse epididymis using the peroxidase-antiperoxidase and protein A-gold methods. The most proximal staining with anti-CP 27 was in segment 6 of the distal caput epididymidis, where the lumen and a portion of the supranuclear cytoplasm of principal cells were stained. In contrast, in the distal corpus and cauda epididymidis (segments 8-11), there was pronounced staining of the luminal contents, sterocilia, and scattered cells identified as the "light" cells of the epididymal epithelium. Although CP 27 was found in the epididymal lumen of all segments distal to segment 6, the intensity of staining appeared to decline distally in the cauda epididymidis. Control sections exposed to pre-immune serum instead of anti-CP 27 showed no reaction. The results suggest that CP 27, the major glycoprotein of cauda epididymal fluid, is synthesized by principal cells of segment 6 of the distal caput epididymidis. CP 27 may be among the substances absorbed from the lumen by the light cells of the distal epididymis.

Maturation antigen of the mouse sperm flagellum. I. Analysis of its secretion, association with sperm, and function

We report here recent findings on the sperm maturation antigen SMA4, which is secreted by holocrine cells of the distal caput epididymis and binds to the flagellar surface of mouse sperm during epididymal transit. Washed sperm from the caput and corpus epididymides of mice were examined by immunofluorescence and SDS-PAGE using wheat germ agglutinin, which binds specifically to SMA4 as a primary probe. Results indicate that sperm first exhibit WGA reactivity on their flagellae in the region of the distal caput, and that the appearance of WGA receptors is due to the binding of a 54-Kd glycoprotein (SMA4) to the cell surface. Extracts of epididymis containing SMA4 were tested for their ability to bind to the surfaces of caput and corpus sperm. Caput sperm surfaces bound SMA4 in a temperature-independent manner, and binding occurred in the presence of enzyme inhibitors, suggesting a nonenzymatic process. Biochemical studies revealed that SMA4 contains disulfide bonds which stabilize it on the sperm surface and restrict its mobility. Terminal carbohydrate residues of the molecule are sialic acids. The addition of SMA4 to caput sperm flagellae prevented tail-to-tail agglutination, normally seen when caput sperm are diluted into saline; and SMA4 was able to disperse clumps of agglutinated caput sperm. The data suggest that a primary function of SMA4 is to prevent tail-to-tail agglutination of sperm during storage in the epididymis.

The ductuli efferentes of the goat: a morphological study

The morphology of the ductuli efferentes of the goat was compared with that of other animal species, especially with that of the bull. Both in the goat and in the bull, it forms a slightly brownish, bulbous mass of highly convoluted ductules (18-19 in the goat, 13-16 in the bull) that occupies approximately one third of the first limb of the caput epididymidis. The epithelium consists of two major cell types, ciliated and nonciliated, and a few intraepithelial lymphocytes and macrophages. The nonciliated cells can be further divided into three types: type II cells are characterized by specific granules that are dense, mostly homogeneous, eosinophilic, osmiophilic, and positive to periodic acid-Schiff (PAS) staining; type III cells are characterized by specific vacuoles that appear empty and do not stain with PAS, eosin, or osmium; type I cells lack both granules and vacuoles. These morphological, histochemical, and tinctorial differences observed among nonciliated cell types suggest that they are probably independent cell types rather than functional stages of one cell type. All three cell types are endowed with absorptive features such as microvilli, pinocytotic vesicles, and subapical vacuoles, but a higher differentiation of these features in type III cells suggests their greater role in the absorption of testicular fluid. Whether granules of type II cells and vacuoles of type III cells are absorptive and/or secretory remains unresolved from the available data. However, some circumstantial evidence, as presented in the discussion, supports the latter possibility.

The intracellular pathway of antagglutinin secretion in the boar caput epididymidis as revealed by immunogold labelling

Antagglutinin, a specific protein synthesized by the boar epididymis, was localized by an ultrastructural immunogold-labeling procedure in the principal cells of the three regions of the caput epididymidis, most notably at the sites of synthesis and secretion. The intensity of the reaction was variable in the three epididymal zones. Labeling was of low intensity in the proximal and middle caput, except in the granules of the latter. These granular "storage sites" did not correspond to typical secretory granules but appeared to be intracellular sites of degradation of this protein. In the distal caput, which was devoid of these granules, intense secretory activity for antagglutinin was detected. Few gold particles were localized in the RER profiles but labeling was detected in the Golgi zone, in numerous dense vesicles, in structures distributed between the Golgi zone and the apex of the cell, and in the epididymal lumen. This study has enabled us to visualize immunocytochemically antagglutinin along its intracellular secretory pathway, i.e. at the site of its synthesis, during its passage via the Golgi zone, and its intracellular transport to the lumen.

Maturation antigen of the mouse sperm flagellum: II. Origin from holocrine cells of the distal caput epididymis

During epididymal transit, the mouse sperm flagellum acquires a surface glycoprotein (SMA4) from epididymal fluid that functions as a sperm antiagglutinin. To determine the origin of this molecule, testes and epididymides of male mice were sectioned for light microscopy and stained with wheat germ agglutinin (WGA)-peroxidase, a probe that has been used previously to examine the biology of SMA4. WGA reactivity was localized to the cytoplasm in a small population of cells in the distal caput epididymis. Testis cells and principle cells of the caput were nonreactive with WGA, while stereocilia were stained on principle cells in the corpus and cauda. The WGA-positive cells in the distal caput were identified as holocrine cells on the basis of morphology, distribution, and PAS + reaction. At high magnification, intense WGA reactivity was due to the presence of numerous apical granules in the cytoplasm. The location of the cells in distal caput coincided exactly with the region of tubule in which sperm first acquired SMA4 on their flagellae. These data suggest that holocrine cells near the junction of caput and corpus epididymis are the source of the sperm antiagglutinin SMA4.

Structure and function of the epididymis

Testicular spermatozoa are functionally immature in that they cannot fertilize ova. It was first demonstrated by Young that spermatozoa undergo certain changes as they migrate through the epididymis. He proposed that spermatozoa ripen during epididymal transit. It is now known that specific maturational changes occur in spermatozoa during epididymal transit which result in their developing the ability to fertilize ova. Concomitant with this functional maturity are changes in spermatozoal morphology, motility, chemistry, permeability, density and metabolism. It is apparent that in some way not understood these changes are necessary for sperm to achieve the ability to complete the fertilization process. When these mechanisms are understood, we may be able to effectively treat conditions such as necrospermia or abnormally low sperm motility. Furthermore, with the development of the hamster-egg penetration test a "new" type of male infertility has become evident in recent years; the inability of otherwise normal sperm to penetrate an ovum. It is during epididymal transit that this ability is normally acquired. Thus, any insight into how sperm attain the capacity to penetrate an ovum could lead to an effective treatment of patients whose sperm do not have this ability. In addition, the epididymis holds significant promise as the site of action for a male contraceptive. Thus, it is the purpose of this review to describe the structure and function of the mammalian epididymis with particular emphasis on the factors regulating sperm maturation.

Reproduction in the male honey possum (Tarsipes rostratus: Marsupialia): the epididymis

The epididymis of the adult honey possum, Tarsipes rostratus, is enclosed by a heavily pigmented tunica vaginalis and lies with the testis in a prominent prepenile scrotum. It is connected to the testis by a single ductus efferentis and is lined by approximately equal numbers of cuboidal ciliated and principal cells. It is unusual for marsupials in having no well-defined compartments or fibrous septae and in having extensive convolutions of the duct only at the caudal flexure. Three principal functional zones (initial, middle, and terminal segments) were identified in the epididymis, based on epithelial type and ultrastructural evidence of sperm maturation. Luminal diameter increases progressively throughout the tract, and epithelial height variations (from about 2 to 20 microns) are greatest in the terminal segment. The epithelium itself is remarkably low (maximum of 21.6 microns) compared with that seen in the epididymis of other mammals. The thickness of the peritubular smooth muscle coat increases close to the junction of the epididymis and ductus deferens. Sperm concentrations were estimated from counts of sperm nuclei and thus can be no more than approximations. The figures are consistent, however, with a rapid increase in concentration in the initial segment, indicating extensive fluid resorption. Sperm concentrations appear to peak in the distal zone of the terminal segment, although sampling problems and wide variations in count make such a conclusion only tentative. Principal and basal cells are the predominant cell types in the epididymal epithelium. Basal cells are most abundant in the initial and distal middle segment. Principal cells show structural evidence of active exchange with the luminal contents and have abundant apical stereocilia, the structure of which depends on the epididymal zone. Other cell types occur less commonly in the epithelium. Lipid-rich and phagocytic principal cells are restricted to the middle and distal zones of the middle segment, respectively. Clear cells, restricted to the terminal segment, and halo cells were found in very low numbers. As in some other marsupials, principal cells (possibly specialized for this function) selectively remove cytoplasmic droplets and probably other cellular debris from the luminal contents. In Tarsipes, however, this process is not very efficient, and many discarded droplets pass through to the terminal segment where they form large masses of debris associated with aggregates of degenerating spermatozoa.

Subcellular distribution of the nonspecific esterase in the mouse epididymis with special reference to regional differences

The subcellular distribution of esterases was studied in mouse epididymis by using 5-bromo-indoxyl-acetate as a substrate. In all the cells of the duct, a low level of esterase activity was detected except in one of the five segments of the head--segment IV; in one of the three types of apical cells--the "prominent cells"; and in the "clear cells" scattered in the middle and distal parts. In these cells, the intensity of the reaction was high. The reaction product was consistently found in the endoplasmic reticulum and was more abundant in cells showing a high level of activity than in others. In cells with low esterase activity, the reaction was mainly restricted to this organelle. In highly active cells, the spectrum of subcellular locations was selectively enlarged and esterase was demonstrated in almost all cell compartments, including the cell membrane, nuclear envelope, mitochondria, lytic structures, and, more rarely in the Golgi apparatus or microvilli. These locations were dependent on cell type. A weak enzyme activity also appeared on mature spermatozoa.

Postnatal differentiation of the enzymatic activity of the mouse epididymis

Dehydrogenase and hydrolase activities were assessed histochemically during postnatal development of the mouse epididymis. At birth the activities of various enzymes were demonstrable along the epithelium at the same intensity. Variations occurred in the intensity of enzyme activities in principal cells, leading to regional differentiation which progressed according to an ascending pattern from the distal part (2nd week) to the medial and proximal parts (3rd week). The proximal part reached its definitive differentiation at the 4th week when the 5 segments characteristic of the adult state were distinguishable. At the same time, 3 types of "apical cells" (narrow, prominent and mitochondria-goblet cells) in the proximal part and "clear cells" in the medial and distal parts showed higher activity of several enzymes (dehydrogenases, acid phosphatase, Ca2+-ATPase) than did adjacent principal cells. This histochemical data has led us to propose a model for epididymal cell differentiation in the mouse. The role of androgens in the development of those regional differences is discussed.

Effect of castration on lectin staining in rat epididymis

Seven rhodamine-conjugated lectins (PNA, RCA I, Con A, WGA, UEA I, SBA, DBA) were used to follow the staining pattern of the rat epididymis at different time points after castration. The affinity of the intratubular sperm mass for the lectins increased rapidly with concurrent augmentation of the staining in the principal cells but a decline of the reaction in the light cells. The light cells showed some differences in their response to castration, which was compatible with secretory/absorptive activity in caput and absorptive activity in cauda. The active phase of sperm mass destruction and epithelial involution was accompanied by local accumulation of macrophages and round cells, which also acquired an increased affinity for most of the lectins. It is concluded that the androgen-deprived epididymis is rapidly programmed for autolytic and phagocytic processes, which include the destruction of macromolecules including glycoproteins of the spermatozoa.

Fluid-phase and adsorptive endocytosis in ciliated epithelial cells of the rat ductuli efferentes

Ciliated cells of the ductuli efferentes show at their apex a discrete endocytic apparatus composed of small vesicles connected to or subjacent to the apical plasma membrane, small apical membranous tubules, and pale multivesicular bodies. Deeper in the cytoplasm, there are acid phosphatase-positive denser, multivesicular bodies and secondary lysosomes showing an electron-dense cortex and a crystalline, paler stained core. Cationic ferritin and concanavalin A-ferritin used to demonstrate adsorptive endocytosis, when injected into the rete testis, rapidly reached the lumen of the ductuli efferentes. At 1 min after injection, these tracers were seen bound to the apical plasma membrane of ciliated cells and within small endocytic vesicles and by 5 min in narrow apical tubules. At 15 and 30 min after injection, the tracers appeared in pale multivesicular bodies while at 1 hr they were found within dense multivesicular bodies. At 2 hr and longer time intervals these tracers accumulated within secondary lysosomes. Native ferritin, concanavalin A-ferritin in the presence of alpha-methyl-D-mannoside, and horseradish peroxidase or albumin-colloidal gold complexes were used to analyze fluid-phase endocytosis. At various intervals following their injection into the rete testis, these tracers presented a distribution identical in all respects to that described for cationic ferritin and concanavalin A-ferritin. In the present work, none of the above tracers were transported to the abluminal aspect of the ciliated cells. These cells, like the nonciliated epithelial cells of the ductuli efferentes are thus involved in adsorptive as well as in fluid-phase endocytosis.

Morphology of the bovine epididymis

The epididymis of the bull was divided into six regions, and morphological differences between regions were studied. The epithelium of all regions contained four cell types: principal and basal epithelial cells, and intraepithelial lymphocytes and macrophages. The epithelium of regions II-V also contained a few apical cells. Principal cells of all regions possessed an endocytotic apparatus including stereocilia underlain by canaliculi, coated vesicles, and subapical vacuoles (up to 1 micron in diameter); however, large vacuoles with a flocculent content and multivesicular bodies (up to 5 microns in diameter) were most numerous in regions II, III, and IV. The unique features of principal cells of region I were the presence of well-developed Golgi bodies, few lipid droplets, and whorls of smooth endoplasmic reticulum in the supranuclear cytoplasm. Numerous mitochondria, distended cisternae of rough endoplasmic reticulum, and dense granules characterized the infranuclear cytoplasm of the principal cells of regions II-VI; however, these features were more developed in region V. Apical cells were characterized by the apical location of the nucleus, many mitochondria in the apical cytoplasm, and few microvilli at the luminal border. Basal cells with few cytoplasmic lipid droplets were present throughout the length of the epididymis but appeared more numerous in region V. Intraepithelial lymphocytes were present at all levels of the epithelium but were never seen in the lumen. Intraepithelial macrophages containing heterogeneous granules, eccentric nuclei, and pseudopods were invariably seen near the basal area of the epithelium in all regions. These observations are discussed in an effort to define the role of each cell type in the epididymal epithelium.

Autoradiographic study of labeled amino acid incorporation into clear cells of mouse epididymis

Protein synthesis in clear cells of mouse epididymis was investigated by quantitative autoradiography after intravenous injection of tritium-labeled leucine, arginine, and lysine. Labeling occurred in the cytoplasm after 2 min and persisted for 240 min after injection. The silver grains were located not only on the organelles involved in protein synthesis (rough endoplasmic reticulum, Golgi apparatus) but also on those implicated in reabsorption (multivesicular bodies). Quantitative analysis showed a peak in radioactivity in the rough endoplasmic reticulum, at 10-15 min, followed by a peak in the multivesicular bodies at 15 min. Labeling of the Golgi apparatus reached its maximum at 30 min. Radioactivity in the apical plasma membrane remained low and relatively stable. These results indicate that clear cells synthesize proteins, a large part of which is transferred to the multivesicular bodies that participate in the cellular absorptive function.

Effect of sympathetic denervation of rat internal genitalia on daily sperm output

Using the technique of vasocystostomy, daily sperm output was determined in rats undergoing surgical removal of the sympathetic nerves to the internal genitalia. Between ten and fourteen days after denervation, the daily sperm output significantly (p less than 0.001) decreased below presurgical rates and those of sham-operated control animals (p less than 0.01). This change occurred without changes in plasma testosterone concentration or testicular histology. These data suggest neural control of sperm transport in the rat.

The secretory pathway in the mouse epididymis as shown by electron microscope radioautography of principal cells exposed to monensin

The secretory pathway in principal cells of the mouse epididymis was studied using in vitro labeling and electron microscope radioautography of tissue exposed to the ionophore monensin. After a 5-minute pulse of 3H-leucine, control samples of caput epididymidis were incubated in a modified Krebs-Ringer solution (MKRH medium), while experimental specimens were placed in the same medium, to which 1 microM monensin had been added. At intervals between 5 minutes and 4 hours, samples were fixed and prepared for electron microscope radioautography. Analysis of control specimens revealed heaviest labeling of the rough and the sparsely granulated endoplasmic reticulum early in the experiment followed by a fall in radioactivity, maximal labeling of the Golgi apparatus at 30 minutes, and a pronounced rise in the percentage of grains associated with the apical cell surface and the epididymal lumen beginning 1 hour after administration of precursor. In monensin-treated epididymides, radioactive material accumulated in the Golgi region while the normal increase in labeling of the apical surface and the lumen was completely inhibited for at least 2 hours. The percentage of grains attributed to coated vesicles was also reduced in samples exposed to monensin. In contrast, labeling patterns of the abundant, sparsely granulated, endoplasmic reticulum and the rough endoplasmic reticulum were very similar in monensin-treated and control specimens. The concomitant alterations in labeling of the Golgi apparatus and the lumen demonstrate that the Golgi apparatus participates in intracellular transport of secretory proteins in epididymal principal cells, and is not bypassed as previously suggested. The percentage of grains associated with the sparsely granulated endoplasmic reticulum suggests that much of the synthesis of secretory protein in the principal cells occurs in this organelle, and the lack of alteration of its labeling in the presence of a monensin-induced block at the level of the Golgi apparatus indicates that the sparsely granulated endoplasmic reticulum lies before the Golgi apparatus in the secretory pathway. It is speculated that vesicles play a role in transport of secretory protein from the Golgi apparatus to the lumen.

Endocytosis in nonciliated epithelial cells of the ductuli efferentes in the rat

The nonciliated cells lining the ductuli efferentes presented three distinct cytoplasmic regions. The apical region contained, in addition to cisternae of endoplasmic reticulum and mitochondria, two distinct membranous elements. The tubulovesicular system consisted of dilated tubules connected to the apical plasma membrane and subjacent distended vesicular profiles. The apical tubules, not connected to the cell surface, consisted of numerous densely stained tubules of small size which contain a compact, finely granulated material. The supranuclear region, in addition to a Golgi apparatus and ER cisternae, contained dilated vacuoles, pale and dense multivesicular bodies, as well as numerous dense granules identified cytochemically as lysosomes. The basal region contained the nucleus and many lipid droplets. The endocytic activity of these cells was investigated using cationic ferritin (CF) and concanavalin-A-ferritin (Con-A-ferritin) as markers of adsorptive endocytosis; and native ferritin (NF), concanavalin-A-ferritin in the presence of alpha-methyl mannoside, and horseradish peroxidase or albumin bound to colloidal gold for demonstrating fluid-phase endocytosis. These tracers were injected separately into the rete testis, and animals were sacrificed at various time intervals after injection. At 1 min, CF or Con-A-ferritin were seen bound to the apical plasma membrane, to the membrane of microvilli, and to the membrane delimiting elements of the tubulovesicular system. Between 2 and 5 min, these tracers accumulated in the densely stained apical tubules and at 15 min in the dilated vacuoles. Between 30 min and 1 hr, the tracers appeared in multivesicular bodies of progressively increasing density, whereas at 2 hr and later time intervals, many dense lysosomal elements became labeled. The tracers for fluid-phase endocytosis showed a distribution similar to that for CF or Con-A-ferritin except that they did not bind to the apical plasma membrane, microvilli, or membrane delimiting the tubulovesicular system. At no time interval were any of the tracers observed in the abluminal spaces. Thus, the nonciliated epithelial cells of the ductuli efferentes are actively involved in fluid-phase and adsorptive endocytosis, both of which result in the sequestration of endocytosed material within the lysosomal apparatus of the cell.

Regional differences of the proximal part of mouse epididymis: morphological and histochemical characterization

Regional differences in the proximal part of mouse epididymis were reported to provide a morphological baseline for studies on functional zonation of this part that is critical in sperm maturation. Macroscopical, histological, ultrastructural, and histochemical observations permitted us to subdivide this part into five segments, characterized by epithelial height, nuclear position, cytological and histochemical features of principal cells. Segment I corresponded to the initial segment previously described in rodents. Segment II differed from segment I by endoplasmic reticulum (ER) and dictyosomes aspect in principal cells, apical alkaline phosphatase and Ca2+-dependent ATPase activities. Segment III was characterized by spermatozoa package, high content of cells in multivesicular bodies, mitochondria shape, complex interdigitating membranes, and strong periodic acid-Schiff (PAS)-positive cell border. Segments IV and V presented the same cytological features but differed by their esterase activity. In the principal cells of each segment, dense spherical concretions were scattered in ER caveolae. Cells with apical nuclei were classified into two groups. The cells of the first group presented the same morphological and histochemical features as the adjacent principal cells and were scattered in the five segments ("apical cells"). The cells of the second group differed from the others by their goblet shape, a dense cytoplasm, and a high mitochondria succinate-D activity. They presented different cytological and histochemical features depending on their localization in segments I ("narrow cells"), II ("prominent cells"), or III, IV, V ("mitochondria goblet-cells"). The possible relationships between epithelium structure and epididymal functions were herein discussed.

Regulation of rat caput epididymidis contractility by prostaglandins

Mechanical activity of the rat caput epididymidis in vitro was recorded using a videomicrography system. The effects of prostaglandin (PG)F2 alpha, PGE2, and aspirin on caput epididymidis contractility were determined by measuring the frequency of contraction, luminal diameter, and amplitude of contraction at various concentrations of each test compound in vitro. PGF2 alpha stimulated contractility of the tubules at physiological concentrations, while PGE2 reduced contractility. Aspirin strongly inhibited contractility at concentrations of 10(-3) and 10(-2)M. Endogenous levels of PGF2 alpha and PGE were determined for rat testes, caput, corpus, and cauda epididymidis and vas deferens. While the concentrations of PGE were consistently higher than those of PGF2 alpha, both compounds were relatively low in the testes, high in the vas deferens, and intermediate throughout the epididymis. Results from these experiments strongly suggest that PGs are important regulators of proximal epididymidis contractions and thus may regulate sperm transport through that organ.

Seasonal changes in fine structure of the ductuli efferentes of the ground squirrel, Citellus lateralis (Say)

The morphological changes that the ductuli efferentes undergo during the seasonal breeding cycle of the ground squirrel Citellus lateralis were examined by means of electron microscopy. At the time of spermatogenetic activity the epithelium of the ductuli was composed of highly differentiated principal and ciliated cells. Distinctive cytological features of these cells during this period were the presence of a heterogeneous collection of numerous membrane-bound granules in principal cells and large accumulations of glycogen in ciliated cells. Structurally these cells were specialized for movement of luminal contents and its modification by absorption and possible secretion. With the onset of testicular regression, profound changes occurred in both cell types. Initially the lumen of the ductuli became occluded by masses of apical cytoplasm protruded from principal and ciliated cells as well as by degenerating cells which had been sloughed from the epithelium. This leads eventually, by the time of complete testicular regression, to reduced ductuli containing cells smaller in size with fewer organelles than those present during the period of spermatogenesis. The membrane-bound granules in principal cells and the accretions of glycogen in ciliated cells had now virtually disappeared. There was, however, a dramatic increase in dense inclusions representing deposits of lipofuchsin. As yet the cellular mechanisms controlling and effecting these dramatic changes in morphological appearance are unknown.