Postnatal study on the histology and histochemistry of ductuli efferentes testis in buffalo (Bubalus bubalis) from birth to one and a half years.

The efferent ductules were situated between the cranial border of the testis and the head of epididymis. The ductules were highly convoluted and formed a conical mass embedded in the dense irregular connective tissue near region I of the head of epididymis. Simple columnar with a few cuboidal cells characterised the epithelium at 3-32 weeks, whereas in later stages of development it was mainly cuboidal with a few columnar cells. The basal cells were also observed lining the basement membrane in some of the tubules. The cells were devoid of cilia, smooth muscles surrounding the tubules were absent. PAS-reactive carbohydrates, glycogen, acid mucopolysaccharides, alkaline phosphatase were demonstrated on the efferent ductules at different stages of postnatal study.     

Efferent ductules of the fan-throated lizard Sitana ponticeriana Cuvier: light and transmission electron microscopy study

Light microscopy histology of efferent ductules and the ultrastructural organization of their epithelium were studied in the fan‐throated lizard Sitana ponticeriana Cuvier. The ductules of this lizard are extra‐testicular and arise from an extra‐testicular rete testis. A major portion of the ductules is intra‐epididymal and occupies the cephalic end of the epididymis. The ductules differentiate histologically into proximal and distal portions. The epithelium is formed of two major tall columnar cell types, the non‐ciliated and ciliated, and one minor cell type, the basal cells. Dark cells were also identified. The non‐ciliated cells possess microvilli towards the luminal end, tubular coated pits at the bases of the microvilli, coated vesicles in the apical cytoplasm and multivesicular bodies, lysosomes and mitochondria in the supranuclear and perinuclear cytoplasm, which reflects their role in the uptake of the material they are processing. These cells also participate in spermiophagy. The ciliated cells reflect their role in mixing the luminal content and/or its transport to the distal parts of the male tract. The lizard efferent ductules share many features in common with those of mammals and a crocodile and several other features with birds and a turtle. Spermiophagy by the efferent ductules is reported here for the first time in a reptile.     

Ultrastructure of the reproductive system of the black swamp snake (Seminatrix pygaea). VI. Anterior testicular ducts and their nomenclature

In this study, the anterior testicular ducts of the North American natricine snake Seminatrix pygaea are described using light and electron microscopy. From the seminiferous tubules, the rete testis passes into the epididymal sheath, a structure along the medial border of the testis heavily invested with collagen fibers. The rete testis consists of simple, nonciliated cuboidal epithelium (principal cells). The intratesticular ducts of the rete testis are narrow (50–70 μm) at their junction with the seminiferous tubules, widen (80–100 μm) as they extend extratesticularly, and divide into smaller branches as they anastomose with the next tubules, the ductuli efferentes. The ductuli efferentes are lined by simple cuboidal epithelium but possess nonciliated principal cells as well as ciliated cells. These are the only ducts in the male reproductive system with ciliated cells. The ductuli efferentes are narrow (25–45 μm), divide into numerous branches, and are highly convoluted. The ductus epididymis is the largest duct in diameter (240–330 μm), and the diameter widens and the epithelium thins posteriorly. The ductus epididymis is lined by nonciliated, columnar principal cells and basal cells. No regional differences in the ductus epididymis are apparent. Ultrastructural evidence suggests that all of the nonciliated principal cells in each of the anterior testicular ducts function in both absorption and secretion. Absorption occurs via small endocytic vesicles, some of which appear coated. Secretion is by a constitutive pathway in which small vesicles and a flocculent material are released via a merocrine process or through the formation of apocrine blebs. The secretory product is a glycoprotein. Overall, the characteristics of the anterior testicular ducts of this snake are concordant with those of other amniotes, and the traditional names used for snakes are changed to conform with those used for other sauropsids and mammals. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

Differential expression of estrogen receptors alpha and beta in the reproductive tracts of adult male dogs and cats

Expression of estrogen receptors (ERs) in the reproductive tracts of adult male dogs and cats has not been reported. In the present study, ERalpha and ERbeta were localized by immunohistochemistry using ER-specific antibodies. ERalpha was found in interstitial cells and peritubular myoid cells in the dog testis, but only in interstitial cells of the cat. In rete testis of the dog, epithelial cells were positive for ERalpha staining, but in the cat, rete testis epithelium was only weakly positive. In efferent ductules of the dog, both ciliated and nonciliated cells stained intensely positive. In the cat, ciliated epithelial cells were less stained than nonciliated epithelial cells. Epithelial cells in dog epididymis and vas deferens were negative for ERalpha. In the cat, except for the initial region of caput epididymis, ERalpha staining was positive in the epithelial cells of epididymis and vas deferens. Multiple cell types of dog and cat testes stained positive for ERbeta. In rete testis and efferent ductules, epithelial cells were weakly positive for ERbeta. Most epithelial cells of the epididymis and vas deferens exhibited a strong positive staining in both species. In addition, double staining was used to demonstrate colocalization of both ERalpha and ERbeta in efferent ductules of both species. The specificity of antibodies was demonstrated by Western blot analysis. This study reveals a differential localization of ERalpha and ERbeta in male dog and cat reproductive tracts, demonstrating more intensive expression of ERbeta than ERalpha. However, as in other species, the efferent ductules remained the region of highest concentration of ERalpha.     

Aquaporin-1 and -9 are differentially regulated by oestrogen in the efferent ductule epithelium and initial segment of the epididymis

BACKGROUND INFORMATION: Efferent ductules reabsorb more than 90% of the rete testis fluid, a process that involves ion transporters and AQP (aquaporin) water channels. Oestrogen has been shown to modulate the expression of the ion transporters involved in this activity, but reports of AQP regulation in the male tract have been confounding. To understand better the regulation of AQP1 and AQP9, we investigated their expression in rat efferent ductules and initial segment of the epididymis after treatment with the pure antioestrogen ICI 182,780 or bilateral efferent duct ligation, or castration, followed by hormone replacement. RESULTS: Results show that AQP9 is modulated by oestrogen in the efferent ductule epithelium, but not in the initial segment of the epididymis. DHT (5alpha-dihydrotestosterone) also modulated AQP9 in efferent ductules. AQP9 was down-regulated by the antioestrogen in efferent ductules on day 45 post-treatment, which occurred before the non-ciliated cells had shown significant loss of microvilli. DHT, but not oestradiol, modulated AQP9 expression in the initial segment of the epididymis. In contrast, testosterone, DHT, oestrogen or the antioestrogen did not alter AQP1 staining, indicating constitutive expression of AQP1 in the efferent ductule epithelium. AQP1 expression was induced in peritubular cells of efferent ductules and in the initial segment of the epididymis after castration and long-term treatment with the antioestrogen. Although peritubular AQP1 staining in efferent ductules was partially reversed by the androgens, it was not reversed after any treatment in the initial segment of the epididymis. CONCLUSIONS: These results demonstrate that efferent ductules are unique in requiring both oestrogen and androgen to regulate an important mediator of fluid reabsorption, whereas the initial segment is dependent only on androgen stimulation.     

Immunolocalization of androgen and vitamin D receptors in the epididymis of mature ram (Ovis aries)

This study illustrated the immunohistochemical distribution of androgen and vitamin D receptors of epididymis in 20 sexually mature ram (Rahmani breed) with average age ranged from (2^_4) years and average weight ranged from (50^_65kg). Androgen receptor was localized in the cytoplasm of both ciliated and non ciliated cells of efferent ductules, besides the principal cells via the entire epididymal duct. The principal cells of both corpus and proximal cauda epididymis showed the highest immunoreactivity to androgen receptors. Furthermore, vitamin D receptor was localized in the cytoplasm of all epithelium of the efferent ductules besides principal cells of all epididymal regions, however the immunoreaction was significantly higher in the efferent ductules, distal caput and distal cauda epididymis. In conclusion, these results suggest that the function of ram epididymis is regulated by both androgen and Vitamin D.     

The rete testis of the goat, a morphological study

The rete testis of the goat can be divided into three parts, septal, mediastinal and extratesticular. The septal rete is short, relatively straight and connects the terminal part of the seminiferous tubules with the mediastinal rete. The mediastinal rete is a labyrinth of intercommunicating channels that occupies about two-thirds of the central axis of the testis. The extratesticular rete is located outside the testis at its extremitas capitata and forms sac-like dilations up to 2 mm in diameter. The rete testis, regardless of its location, is lined by simple cuboidal to simple squamous epithelium that invariably contains a few intra-epithelial lymphocytes and macrophages. The epithelial cells possess few microvilli and a centrally located flagellum at the luminal border. With the exception of a few small vesicles in the apical cytoplasm, morphological features associated with absorption such as coated vesicles, canaliculi, vacuoles and multivesicular bodies are absent. However, basolateral interdigitations between adjacent cells, another feature of absorptive epithelium, are frequently noticed. Most cytoplasmic organelles except mitochondria and free ribosomes are poorly developed, suggesting that caprine rete epithelial cells are not associated with protein/glycoprotein secretion. There is no evidence of sperm phagocytosis by the rete epithelium, but luminal macrophages containing sperm fragments are occasionally encountered. The structural-functional relationships of the rete epithelial cells are discussed.     

Morphology of the epithelium of the extratesticular rete testis, ductuli efferentes and ductus epididymidis of the adult male rabbit

The fine structure of the epithelium lining the extratesticular rete testis, ductuli efferentes and ductus epididymidis of the rabbit has been investigated. In the ductuli efferentes the epithelium is composed of two cell types, principal cells and ciliated cells. The latter type is distinguished from principal cells by the presence of cilia projecting into the lumen and the position of the nucleus in the apical half of the cell. Principal cells in this segment are characterized by micropinocytotic vesicles on the surface plasma membrane and a variety of small dense bodies scattered throughout the cytoplasm. In the ductus epididymidis basal cells replace ciliated cells as the second cell type, but differences between various segments of the epididymis are related to the fine structure of the principal cells. In the proximal caput epididymidis (Nicander's region 1) the principal cells are tall with long microvilli. They typically contain a small Golgi apparatus and a cluster of dense bodies adjacent to the nucleus. In the distal caput epididymidis (Nicander's regions 2-5) the apical cytoplasm of principal cells is filled with numerous micropinocytotic vesicles and large multivesicular bodies; these features are interpreted as signs of absorptive activity. The multivesicular bodies are absent from the cytoplasm of principal cells in the corpus epididymidis (Nicander's region 6) and, instead, numerous elements of smooth endoplasmic reticulum, a large Golgi apparatus, lipid droplets and dense bodies characterize principal cells in this segment. Towards the proximal cauda epididymidis (Nicander's region 7), the number of dense bodies (lysosomes) in the cytoplasm increases considerably. In the globose cauda (Nicander's region 8), the principal cells are reduced in height, and in addition to the features described in region 7, are characterized by a concentric array of rough endoplasmic reticulum in the basal cytoplasm. These observations are discussed in relation to the role of the epididymis in promoting the maturation and survival of spermatozoa.     

Organization of tubules in the human caput epididymidis and the ultrastructure of their epithelia

The structure of the human caput epididymidis was examined by gross morphological and light and electron microscopic techniques. There were at least seven types of tubules, each characterized by a different epithelium. These tubules were connected with one another by at least eight types of junctions to form a network. Most of the caput epididymidis was composed of efferent ducts. Within these, five types of tubules, each with a different ciliated epithelium, were found in different regions; and four types of junctions between the efferent ducts and the epididymal tubule were observed. The efferent ducts left the testis, initially as parallel straight tubules containing both ciliated and non-ciliated cells in an epithelium of irregular height. Each efferent duct then coiled tortuously into lobules that folded over one another. These efferent ducts then branched out as thin tubules to join a network of dark tubules which were lined by a regular epithelium containing prominently vacuolated, non-ciliated cells. These tubules anastomosed via common cavities characterized by a ciliated cuboidal epithelium and sometimes joined tubules exhibiting a non-vacuolated ciliated epithelium. The latter, as well as typical efferent ducts, made connection with the epididymis proper in both end-to-end and end-to-side junctions. In the more distal junctions with the epididymis, the efferent ducts joined to a transitional epididymal ductule before joining to the side of the epididymis proper. Post-junctional epithelia in the beginning of the epididymis occasionally contained patches of cells characteristic of efferent ducts. Tall cells with long stereocilia constituted a discontinuous "initial segment"-like region of the epididymis. This is the most detailed study so far of the epithelia and the tubule organization in the caput epididymidis of any species, and most of the results are reported for the first time for the human. Although the pattern of the tubule network resembles that of some domestic species, the rich variety of epithelia has not been appreciated before.     

Morphologic study of the efferent ductules of the pigeon (Columba livia)

The efferent ductules of the pigeon are localized in the epididymal region and are topographically divided into proximal and distal, both portions being lined with stereociliated pseudostratified epithelium. Transmission electron microscopy shows five distinct cell types: light, dark, and angular non-ciliated cells with possible apocrine secretory role cells and halo cells, possibly intraepithelial leucocytes. The proximal efferent ductules have the widest diameter among all ductules in the epididymal region.     

Morphology and immunolocalization of aquaporins 1 and 9 in the agouti (Dasyprocta azarae) testis excurrent ducts

This study investigated the morphology and immunoexpression of aquaporins (AQPs) 1 and 9 in the rete testis, efferent ducts, epididymis, and vas deferens in the Azara’s agouti (Dasyprocta azarae). For this purpose, ten adult sexually mature animals were used in histologic and immunohistochemical analyses. The Azara’s agouti rete testis was labyrinthine and lined with simple cubic epithelium. Ciliated and non-ciliated cells were observed in the epithelium of the efferent ducts. The epididymal cellular population was composed of principal, basal, apical, clear, narrow, and halo cells. The epithelium lining of vas deferens was composed of the principal and basal cells. AQPs 1 and 9 were not expressed in the rete testis. Positive reaction to AQP1 was observed at the luminal border of non-ciliated cells of the efferent ducts, and in the peritubular stroma and blood vessels in the epididymis, and vas deferens. AQP9 was immunolocalized in the epithelial cells in the efferent ducts, epididymis and vas deferens. The morphology of Azara’s agouti testis excurrent ducts is similar to that reported for other rodents such as Cuniculus paca. The immunolocalization results of the AQPs suggest that the expression of AQPs is species-specific due to differences in localization and expression when compared to studies in other mammals species. The knowledge about the expression of AQPs in Azara’s agouti testis excurrent ducts is essential to support future reproductive studies on this animal, since previous studies show that AQPs may be biomarkers of male fertility and infertility.     

High level of endostatin in epididymal epithelium: protection against primary malignancies in this organ?

Rete testis and epididymis are rare locations for primary tumors or metastasis. Assuming that this may be related to expression level of angiogenic inhibitors, we focused our study on the expression pattern of collagen 18/endostatin. In situ hybridization and immunohistochemistry for collagen 18 and endostatin were carried out on sections of human rete testis and epididymis as well as on epididymal adenoma and human testicular tissue with or without carcinoma in situ (CIS). In situ hybridization revealed strong expression of collagen 18 mRNA in rete testis, efferent ducts and epididymal duct. Immunostaining showed collagen 18 in epithelium and basement membrane as well as in blood vessels of rete testis. Further, in both efferent ducts and epididymal duct, collagen 18 was mainly localized in the basement membrane of these ducts and of the blood vessel wall. Endostatin immunostaining was localized in the epithelium of rete testis, efferent ducts and epididymal duct. This pattern of endostatin staining was absent in epididymal adenoma tissue while tumor associated blood vessels exhibited strong endostatin staining. No endostatin staining was detectable in normal germinal epithelium and CIS cells while Leydig cells exhibited strong endostatin staining. High endostatin expression in epididymis may protect this organ against tumor development. Gene therapeutic strategies providing high expression of endostatin in normal epithelia may be useful to prevent tumor development.     

The histological changes in the testis, epididymis and prostate gland of the red-bellied tree squirrel, Callosciurus erythraeus, during the growth and reproductive cycle

The male reproductive glands of the red-bellied tree squirrel, Callosciurus erythraeus, in the infantile, and prepubertal males, as well as sexually functional, degenerating and redeveloping adults were studied histologically. In the infant, testes are characterized with solid seminiferous tubules filled with primordial germ cells and Sertoli cells. Interstitial cells are sparse. The prostate is composed of condensed cell cords grouped into lobules dispersed with interlobular tissues rich in fibroblasts. In the epididymis the highly convoluted tubule is lined with a simple cuboidal or columnar epithelium and thin smooth musculature without. In the prepubertal male, germ cells are engaged actively in mitosis. Primary spermatocytes are readily recognized. Leydig cells appear in groups in the interstitial tissue. In the prostate, cell cords become highly branched and collecting tubules make their appearance. The tubules in the epididymis are enlarged in diameter but their peripheral musculature becomes thinner. In functional males, meiosis is active and bundles of spermatozoa are scattered along the central lumen. Leydig cells have their cytoplasm highly enriched. The prostate is in the secretory phase. The tubule in the epididymis is filled with sperm. In the degenerating adult, meiosis is interrupted and necrotic germ cells are detached from germinal epithelium. In the prostate, secretory and collecting ducts are eventually reduced to condensed lobules separated by interlobular fibrous tissue. The tubule in the epididymis often fills with necrotic germ cells but no sperm. In the redeveloping adult, the histology of the testes, prostate and epididymis is similar to that of the prepubertal male. However, there is more fibrous tissue in the interlobular septa in the prostate gland and thick musculature at the periphery of the tubule in the epididymis.     

Granular,ciliated cells in the anterior pituitaries of immature rats

Summary In this communication we demonstrate a new type of ciliated cell in the pituitary gland of immature rats. Anterior pituitary glands of rats, 31 days of age, were examined by electron microscopy. Around the agranular cells, which lined small cavities, there were sparsely granulated cells with many cilia (granular, ciliated cells). Their small granules, which were distributed along the cell membrane, had limiting membranes. Their cilia were of 9+2 type with a central pair of micro tubules. It was suggested that the granular, ciliated cells might be an intermediate-type of cell for the different types of pituitary cells, which appear temporarily during pituitary ontogenesis.     

Estrogen receptor alpha has a functional role in the mouse rete testis and efferent ductules

Previous studies of the estrogen receptor-alpha knockout (alpha ERKO) in the male mouse demonstrate that the rete testis and efferent ductules are targets of estrogen. Because the alpha ERKO mouse lacks a functional estrogen receptor alpha (ER alpha) throughout development, it was not known whether the morphological and physiological abnormalities observed in the alpha ERKO male were due to developmental defects or to dysfunctions concurrent with the lack of ER alpha in the tissue. This study was designed to determine if treatment of normal wild-type (WT) mice with the pure antiestrogen, ICI 182,780, (ICI) could reproduce the morphological characteristics seen in alpha ERKO mice. Thirty-day-old male mice were treated for 35 days with either castor oil or ICI. Age-equivalent alpha ERKO mice were used for comparison. Light microscopic examinations of the reproductive tracts revealed dramatic changes in the efferent ductules of treated mice: a 1.7-fold increase in luminal diameter, a 56% reduction in epithelial cell height, a 60% reduction in brush boarder height of nonciliated cells, and an apparent reduction of the number of observable lysosomes and endocytotic vesicles. Testes of ICI-treated mice showed swollen rete testes area (6.5 times larger than control) and a 65% reduction in rete testis epithelium height. However, there were no significant changes in body and testis weights. These results indicate that ER blockage with ICI in WT mice results in morphological changes of the efferent ductules resembling those seen in alpha ERKO siblings of the same age. Based on this study, we conclude that ER alpha has a functional role in the mouse reproductive tract and the aberrant morphology observed in the efferent ductules of the alpha ERKO mouse is likely the result of a concurrent response to the lack of functional ER alpha, and not solely due to the lack of ER alpha during early developmental times.     

Observations on the anterior testicular ducts in snakes with emphasis on sea snakes and ultrastructure in the yellow‐bellied sea snake,Pelamis platurus

The anterior testicular ducts of squamates transport sperm from the seminiferous tubules to the ductus deferens. These ducts consist of the rete testis, ductuli efferentes, and ductus epididymis. Many histological and a few ultrastructural studies of the squamate reproductive tract exist, but none concern the Hydrophiidae, the sea snakes and sea kraits. In this study, we describe the anterior testicular ducts of six species of hydrophiid snakes as well as representatives from the Elapidae, Homolapsidae, Leptotyphlopidae, and Uropeltidae. In addition, we examine the ultrastructure of these ducts in the yellow‐bellied Sea Snake, Pelamis platurus, only the third such study on snakes. The anterior testicular ducts are similar in histology in all species examined. The rete testis is simple squamous or cuboidal epithelium and transports sperm from the seminiferous tubules to the ductuli efferentes in the extratesticular epididymal sheath. The ductuli efferentes are branched, convoluted tubules composed of simple cuboidal, ciliated epithelium, and many species possess periodic acid‐Schiff+ granules in the cytoplasm. The ductus epididymis at the light microscopy level appears composed of pseudostratified columnar epithelium. At the ultrastructural level, the rete testis and ductuli efferentes of P. platurus possess numerous small coated vesicles and lack secretory vacuoles. Apocrine blebs in the ductuli efferentes, however, indicate secretory activity, possibly by a constitutive pathway. Ultrastructure reveals three types of cells in the ductus epididymis of P. platurus: columnar principal cells, squamous basal cells, and mitochondria‐rich apical cells. This is the first report of apical cells in a snake. In addition, occasional principal cells possess a single cilium, which has not been reported in reptiles previously but is known in some birds. Finally, the ductus epididymis of P. platurus differs from other snakes that have been studied in possession of apical, biphasic secretory vacuoles. All of the proximal ducts are characterized by widening of adjacent plasma membranes into wide intercellular spaces, especially between the principal cells of the ductus epididymis. Our results contribute to a larger, collaborative study of the evolution of the squamate reproductive tract and to the potential for utilizing cellular characters in future phylogenetic inferences. J. Morphol. 2012. © 2011 Wiley Periodicals, Inc.     

Expression of constitutively active Notch1 in male genital tracts results in ectopic growth and blockage of efferent ducts, epididymal hyperplasia and sterility

The Notch signaling pathway is involved in a variety of developmental processes. Here, we characterize the phenotypes developing in the reproductive organs of male transgenic (Tg) mice constitutively expressing the activated mouse Notch1 intracellular domain (Notch1(intra)) under the regulatory control of the mouse mammary tumor virus (MMTV) long terminal repeat (LTR). Tg expression was detected in testis, vas deferens and epididymis by Northern blot analysis. In situ hybridization with a Notch1-specific probe lacked sensitivity to detect expression in normal-appearing cells, but demonstrated expression in hyperplastic epithelial cells of the vas deferens, epididymis and efferent ducts. Tg males from three independent founder lines were sterile. Histological analysis of reproductive organs of young Tg males (postnatal ages 8 and 21) showed no difference compared to those of non-Tg males. In contrast, in adult Tg mice from day 38 onwards, the efferent ducts, the vas deferens and most epididymal segments revealed bilateral epithelial cell hyperplasia with absence of fully differentiated epithelial cells. Electron microscopy confirmed the uniformly undifferentiated state of these cells. Immunohistochemistry with anti-PCNA antibody also revealed enhanced proliferation of Tg epididymis. In adult Tg testis, the different generations of germ cells of seminiferous tubules appeared normal, although some tubules were highly dilated and revealed an absence of early and/or late spermatids. The epithelial cells of the Tg tubuli recti and rete testis were not abnormal, but the rete testis was highly dilated and contained numerous spermatozoa, suggesting a downstream blockage. Consistent with a blockage of efferent ducts often seen at the rete testis/efferent duct interface, spermatozoa were absent in epididymis of all adult Tg mice and in all highly hyperplastic efferent duct tubules of these Tg mice. Such a blockage was visualized by injection of Evans blue dye into the rete testis lumen. Finally, the presence of ectopic hyperplastic efferent duct tubules was observed within the testicular parenchyma itself, outside their normal territory, suggesting that Notch1 signaling is involved in the establishment of these borders. This phenotype seems to represent a novel developmental defect in mammals. Together, these results show that constitutive Notch1 signaling significantly affects the development of male reproductive organs.     

Surface specializations of the olfactory epithelium of rainbow trout, Salmo gairdneri

Receptors for olfactory stimulus molecules appear to be located at the surface of olfactory receptor cells. The ultrastructure of the distal region of rainbow trout (Salmo gairdneri) olfactory epithelium was examined by transmission electron microscopy. On the sensory olfactory epithelium, which occurs in the depressions of secondary folds of the lamellae of the rosettes, five cell types were present. Type I cells have a knob-like apical projection which is unique in this species because it frequently contains cilia axonemes within its cytoplasm in addition to being surrounded by cilia. Type II cells bear many cilia oriented unidirectionally on a wide, flat surface. Type III cells have microvilli on a constricted apical surface and centrioles in the subapical cytoplasm. Type IV cells contain a rod-like apical projection filled with a bundle of filaments, and type V cells are supporting cells. Cilia on the sensory epithelium contain the 9 + 2 microtubule fiber pattern. Dynein arms are clearly present on the outer doublet fibers, which suggests that the cilia in the olfactory region are motile. Their presence in olfactory cilia of vertebrates has been controversial. The cilia membrane in this species is unusual in often showing outfoldings, within which are included small, irregular vesicles or channels. In addition, cilia on type II cells frequently contain dense-staining bodies closely apposed to the membranes, along with a densely stained crown at the cilia tip. Previous biochemical evidence indicates that odorant receptors are associated with the cilia.     

Spatial topography of the excurrent duct system in the bovine testis

Summary The rete testis of the bull is situated within an axial mediastinum and consists of approximately 30 longitudinally arranged, anastomosing rete channels. At the cranial testicular pole all rete channels empty into a common space, the area confluens reds, which is subdivided by small septa and narrow chordae retis. The area confluens always contains numerous spermatozoa and is connected with the bulbous initial portions of the efferent ductules by short, often tortuous rete tubules. Since the connection between rete and efferent ductules is situated within the tunica albuginea, the bovine excurrent duct system is not provided with an extratesticular rete as in many other mammals.Straight testicular tubules merge from all directions to connect with superficial rete channels, but the inlets are not evenly distributed. In the periphery each straight tubule begins with a cup-like structure followed by a narrow stalk region and a heavily folded portion opening either immediately into a rete channel or into a tube-like lateral rete extension.In close contiguity to the rete testis lie extremely coiled arterial portions connecting the centripetal and the centrifugal branches of the testicular artery. Since intrinsic musculature is scarcely developed in the mediastinum, and transport of rete content relies primarily on massage due to external pressure changes, the pulsatile blood flow through these coiled arteries may influence conveyance processes within the rete testis.An intimate spatial association between area confluens reds and adjacent large, thin-walled lymph vessels may facilitate a transfer of androgens into the fluid of the rete testis.Supported by the Stiftung zur Förderung der wissenschaftlichen Forschung an der Universität Bern