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

Trade-off between thermal preference and sperm maturation in a montane lizard

Temperature is a key abiotic factor that influences performance of several physiological traits in ectotherms. Organisms regulate their body temperature within a range of temperatures to enhance physiological function. The capacity of ectotherms, such as lizards, to maintain their body temperature within their preferred range influences physiological traits such as speed, various reproductive patterns, and critical fitness components, such as growth rates or survival. Here, we evaluate the influence of temperature on locomotor performance, sperm morphology and viability in a high elevation lizard species (Sceloporus aeneus). Whereas maximal values for sprint speed coincides with field active and preferred body temperature, short-term exposure at the same range of temperatures produces abnormalities in sperm morphology, lower sperm concentration and diminishes sperm motility and viability. In conclusion, we confirmed that although locomotor performance is maximized at preferred temperatures, there is a trade-off with male reproductive attributes, which may cause infertility. As a consequence, prolonged exposure to preferred temperatures could threaten the persistence of the species through reduced fertility. Persistence of the species is favored in environments with access to cooler, thermal microhabitats that enhance reproductive parameters.

The abundance and localization of claudin-1 and -5 in the adult tomcats (Felis catus) testis, tubules rectus, rete testis, efferent ductules, and epididymis

Tight junctions (TJ) are the anatomical component of blood-testis (BTB) and blood-epididymis (BEB) barriers and contain many proteins, including claudins. The presence of claudins in domestic cat testis and epididymis has not been previously described. This study aimed to determine whether claudin-1 and claudin-5 participate in the structure of BTB and BEB and whether their amounts differ between the testis and epididymal segments of adult cats, using Western blotting (WB) and immunohistochemistry. WB results demonstrated that claudin-1 was significantly lower in the testis than in all epididymal segments and higher in the corpus epididymis than in the cauda, while claudin-5 in the testis was significantly lower than in the caput and corpus. Claudin-1 was absent at the Sertoli-Sertoli junctions, while claudin-5 was detected at the level of the BTB during stages I and VIII. Both claudins were observed in the pachytene spermatocytes and the developing acrosome of the round and elongating spermatids. Claudin-5 was also detected in the cytoplasm of some spermatogonia, Sertoli cells, and late spermatid acrosome. In the epididymal segments, both claudins were localized to the area of the tight junctions and along the entire length of the lateral plasma membranes of adjacent principal cells and between principal and basal cells. These results may indicate that in the domestic cat, claudin-1 and -5 participate as both tight junction proteins and adhesion molecules in the BEB's structure, claudin 5 is a component of the BTB, and both proteins may be involved in postmeiotic germ cell development, especially acrosome development.

The expression and localization of Toll-like receptors 2, 4, 5 and 9 in the epididymis and vas deferens of a adult tom cats

Toll-like receptors (TLRs) are important molecules, which provide protection against infections of the reproductive tract. This study demonstrates for the first time the expression and localization patterns of TLRs in the caput, corpus and cauda segments of the epididymal duct (ED) and the vas deferens (VD) of adult domestic cats using immunohistochemistry and western blotting. While immunoblot analyses revealed relatively similar protein levels for TLRs 2, 4, 5, and 9 in three segments of the ED, the protein levels of TLR2 and TLR4 in the VD were found to be significantly higher than those measured in the ED segments (P < 0.05). On the other hand, immunostaining showed that TLRs exhibited regional- and cell-specific localization patterns. TLR2 and TLR5 were immunolocalized to the nucleus and cytoplasm of the principal cells in all ducts. TLR4 was restricted to the stereocilia, and TLR9 was located in the cytoplasm of the principal cells. Narrow cells displayed positive immunoreactions for TLR4 and TLR5. The basal cells of the different ED segments were positive for all four TLRs. TLR2, TLR5 and TLR9 were detected in the cytoplasmic droplets of the spermatozoa. TLR4 and TLR9 were detected along the entire length of the sperm tail, whilst TLR2 and TLR5 were absent in the midpiece. TLR2 and TLR5 were also detected in the equatorial segment of the sperm head. These results suggest that TLR2, TLR4, TLR5 and TLR9 are important not only for the protection of the ED, VD and spermatozoa but also for the maturation and storage of spermatozoa in the ED and VD, respectively.

Macrophages and dendritic cells in the post-testicular environment

Macrophages (MΦ) and dendritic cells (DCs) are heterogeneous families of functionally and developmentally related immune cells that play crucial roles in tissue homeostasis and the regulation of immune responses. During the past 5 years, immunologists have generated a considerable amount of data that challenge dogmas about the ontogeny and functions of these highly versatile cells. The male excurrent duct system plays a critical role in the establishment of fertility by allowing sperm maturation, transport and storage. In addition, it is challenged by pathogens and must establish a protective and tolerogenic environment for a continuous flow of autoantigenic spermatozoa. The post-testicular environment and, in particular, the epididymis contain an intricate network of DCs and MΦ; however, the immunophysiology of this intriguing and highly specialized mucosal system is poorly understood. This review summarizes the current trends in mouse MΦ and DC biology and speculates about their roles in the steady-state epididymis. Unraveling immune cell functions in the male reproductive tract is an essential prerequisite for the design of innovative strategies aimed at controlling male fertility and treating infertility.

Expression of insulin-like factor 3 hormone-receptor system in the reproductive organs of male goats

Relaxin-like factor (RLF), generally known as insulin-like factor 3 (INSL3), is essential for testis descent during fetal development. However, its role in adult males is not fully understood. We investigate the function of INSL3 in male Saanen goats by identifying cell types expressing its receptor, relaxin/insulin-like family peptide receptor (RXFP)2 and by characterizing the developmental expression pattern of INSL3 and RXFP2 and the binding of INSL3 to target cells in the male reproductive system. A highly specific RXFP2 antibody that co-localizes with an anti-FLAG antibody in HEK-293 cells recognizes RXFP2-transcript-expressing cells in the testis. INSL3 and RXFP2 mRNA expression is upregulated in the testis, starting from puberty. INSL3 mRNA and protein expression has been detected in Leydig cells, whereas RXFP2 mRNA and protein localize to Leydig cells, to meiotic and post-meiotic germ cells and to the epithelium and smooth muscle of the cauda epididymis and vas deferens. INSL3 binds to all of these tissues and cell types, with the exception of Leydig cells, in a hormone-specific and saturable manner. These results provide evidence for a functional intra- and extra-testicular INSL3 ligand-receptor system in adult male goats.

Epithelial basal cells are distinct from dendritic cells and macrophages in the mouse epididymis

The epithelium that lines the epididymal duct establishes the optimal milieu in which spermatozoa mature, acquire motility, and are stored. This finely tuned environment also protects antigenic sperm against pathogens and autoimmunity, which are potential causes of transient or permanent infertility. The epididymal epithelium is pseudostratified and contains basal cells (BCs) that are located beneath other epithelial cells. Previous studies showed that in the mouse epididymis, BCs possess macrophage-like characteristics. However, we previously identified a dense population of cells belonging to the mononuclear phagocyte (MP) system (comprised of macrophages and dendritic cells) in the basal compartment of the mouse epididymis and showed that a subset of MPs express the macrophage marker F4/80. In the present study, we evaluate the distribution of BCs and MPs in the epididymis of transgenic CD11c-EYFP mice, in which EYFP is expressed exclusively in MPs, using antibodies against the BC marker keratin 5 (KRT5) and the macrophage marker F4/80. Immunofluorescence labeling for laminin, a basement membrane marker, showed that BCs and most MPs are located in the basal region of the epithelium. Confocal microscopy showed that in the initial segment, both BCs and MPs project intraepithelial extensions and establish a very intricate network. Flow cytometry experiments demonstrated that epididymal MPs and BCs are phenotypically distinct. BCs do not express F4/80, and MPs do not express KRT5. Therefore, despite their proximity and some morphological similarities with peritubular macrophages and dendritic cells, BCs do not belong to the MP system.

Are the basal cells of the mammalian epididymis still an enigma?

Basal cells are present in the columnar pseudostratified epithelium covering the epididymis of all mammalian species, which regulates the microenvironment where the functionally incompetent germ cells produced by the testis are matured and stored. Striking novelties have come from investigations on epididymal basal cells in the past 30–40 years. In addition to an earlier hypothesised scavenger role for basal cells, linked to their proven extratubular origin and the expression of macrophage antigens, basal cells have been shown to be involved in cell–cell cross-talk, as well as functioning as luminal sensors to regulate the activity of principal and clear cells. Involvement of basal cells in the regulation of electrolyte and water transport by principal cells was hypothesised. This control is suggested to be mediated by the local formation of prostaglandins. Members of the aquaporin (AQP) and/or aquaglyceroporin family (AQP3, AQP7 and AQP8) are also specifically expressed in the rat epididymal basal cells. Transport of glycerol and glycerylphosphorylcholine from the epithelium of the epididymis to the lumen in relation to sperm maturation may be mediated by AQP. Most probably basal cells collaborate to the building up of the blood–epididymis barrier through cell adhesion molecules, implying an involvement in immune control exerted towards sperm cells, which are foreigners in the environment in which they were produced.

Plasticity of basal cells during postnatal development in the rat epididymis

Our previous study has shown that basal cells sense luminal factors by forming a narrow body projection that can cross epithelial tight junctions. As a first step toward characterizing the structural plasticity of basal cells, in this study, we followed their appearance and morphology in the rat epididymis and vas deferens (VD) during postnatal development and examined their modulation by androgens in adulthood. Immunofluorescence labeling for cytokeratin 5 showed that basal cells are absent at birth. They progressively appear in a retrograde manner from the VD and cauda epididymis to the initial segments during the postnatal weeks PNW1-3. At the onset of differentiation, basal cells are in contact with the lumen and their nucleus is located at the same level as that of adjacent epithelial cells. Basal cells then position their nucleus to the base of the epithelium, and while some are still in contact with the lumen, others have a 'dome-shaped' appearance. At PNW5-6, basal cells form a loose network at the base of the epithelium, and luminal-reaching basal cells are rarely detected. The arrival of spermatozoa during PNW7-8 did not trigger the development of projections in basal cells. However, cells with a narrow luminal-reaching projection began to reappear between PNW8 and PNW12 in the corpus and the cauda. Treatment with flutamide from PNW10 to PNW12 significantly reduced the number of luminal-reaching basal cell projections. In summary, basal cells exhibit significant structural plasticity during differentiation. Fewer apical-reaching projections were detected after flutamide treatment in adulthood, indicating the role of androgens in the luminal-sensing function of basal cells.

Seasonal variation in estrogen receptor ERα, but not ERβ, androgen receptor and aromatase, in the efferent ductules and epididymis of the big fruit-eating bat Artibeus lituratus

The efferent ductules (ED) are a major target for estrogens, which act via the estrogen receptors ERα (ESR1) and ERβ (ESR2). ERα has been found in the ED of all species studied so far. However, in the epididymis (EP), the expression of ERα is controversial, as is data about the occurrence of aromatase in the epithelium lining the excurrent ducts. Therefore, to further investigate this estrogen-responsive system, we used a seasonal breeder, the Neotropical bat, Artibeus lituratus, in which testicular expression of androgen (AR) and estrogen (ER) receptors vary with reproductive phase. The localization of aromatase, ERα, ERβ and AR in the ED and EP of A. lituratus was investigated. The results showed that aromatase, AR and ERβ were distributed throughout the excurrent ducts and did not vary during the annual reproductive cycle. Conversely, ERα was detected primarily in the ED epithelium, had marked seasonal variation and was increased during regression, especially in the EP epithelium. The results suggest that ERα may be involved in preparing the male genital tract for recrudescence. Together, the data obtained under natural conditions emphasize that specific segments of the excurrent ducts downstream of the testis are the primary targets for estrogen action via ERα, which is similar to previous findings in animals lacking functional ERα.

Immunophysiology and pathology of inflammation in the testis and epididymis

The ability of spermatogenic cells to evade the host immune system and the ability of systemic inflammation to inhibit male reproductive function represent two of the most intriguing conundrums of male reproduction. Clearly, an understanding of the underlying immunology of the male reproductive tract is crucial to resolving these superficially incompatible observations. One important consideration must be the very different immunological environments of the testis, where sperm develop, and the epididymis, where sperm mature and are stored. Compared with the elaborate blood-testis barrier, the tight junctions of the epididymis are much less effective. Unlike the seminiferous epithelium, immune cells are commonly observed within the epithelium, and can even be found within the lumen, of the epididymis. Crucially, there is little evidence for extended allograft survival (immune privilege) in the epididymis, as it exists in the testis, and the epididymis is much more susceptible to loss of immune tolerance. Moreover, the incidence of epididymitis is considerably greater than that of orchitis in humans, and susceptibility to sperm antibody formation after damage to the epididymis or vas deferens increases with increasing distance of the damage from the testis. Although we still know relatively little about testicular immunity, we know less about the interactions between the epididymis and the immune system. Given that the epididymis appears to be more susceptible to inflammation and immune reactions than the testis, and thereby represents the weaker link in protecting developing sperm from the immune system, it is probably time this imbalance in knowledge was addressed.

A dense network of dendritic cells populates the murine epididymis

One of the most intriguing aspects of male reproductive physiology is the ability to generate spermatogenic cells - which are 'foreign' to the host - without triggering immune activation. After leaving the testis, spermatozoa enter the epididymis where they mature and are stored. In this study, we report a previously unrecognized dense network of dendritic cells (DCs) located at the base of the epididymal epithelium. This network was detected in transgenic mice expressing CD11c-EYFP and CX3CR1-GFP reporters. Epididymal DCs (eDCs) establish intimate interactions with the epithelium and project long dendrites between epithelial cells toward the lumen. We show that isolated eDCs express numerous leukocyte markers described previously in other organs that are in contact with the external environment, and present and cross-present ovalbumin to T cells in vitro. eDCs are, therefore, strategically positioned to regulate the complex interplay between immune tolerance and activation, a balance that is fundamental to male fertility.

A single, mild, transient scrotal heat stress causes DNA damage, subfertility and impairs formation of blastocysts in mice

Infertility represents a major clinical problem and 50% of cases are attributable to the male partner. Testicular function is temperature dependent, and in both man and mouse the position of the testes in the scrotum ensures that they are kept at between 2 and 8 °C below core body temperature. We used a mouse model to investigate the impact of a single, transient, mild, scrotal heat stress (38, 40 or 42 °C for 30 min) on testicular function, sperm DNA integrity and embryo survival. We detected temperature-dependent changes in testicular architecture, number of apoptotic cells and a significant reduction in testis weight 7 and 14 days after heat stress at 42 °C. We report for the first time that DNA strand breaks (γ-H2AX-positive foci) were present in spermatocytes recovered from testes subjected to 40 or 42 °C. Fertility of heat-stressed males was tested 23–28 d after treatment (sperm at this time would have been spermatocytes at time of heating). Paternal heat stress at 42 °C resulted in reduced pregnancy rate, placental weight and litter size; pregnancies from the 40 °C group had increased resorptions at e14.5. Abnormalities in embryonic development were detected at e3.5 andin vitrofertilisation with sperm recovered 16 h or 23 d after scrotal stress at 42 °C revealed a block in development between the 4-cell and blastocyst stages. This study has provided evidence of temperature-dependent effects on germ cell DNA integrity and highlighted the importance of an intact paternal genome for normal embryo development.

Spermatotoxic effect of aflatoxin B1 in rat: extrusion of outer dense fibres and associated axonemal microtubule doublets of sperm flagellum

Male Wistar rats were treated with aflatoxin B1 (AFB1). Live as well as methanol-fixed cauda epididymal spermatozoa were stained with acridine orange (AO) and ethidium bromide (EB) and observed under a fluorescence microscope. Giemsa-stained smears were observed in a bright field microscope. Unstained smears were observed with phase contrast illumination. The axoneme of more than 10% of the spermatozoa of treated rats had the outer dense fibres (ODFs), in varying numbers, and the associated axonemal microtubule doublets of the flagellum extruded either at midpiece–principal piece junction or connecting piece. This could be perceived in all light microscopic preparations, but AO–EB staining offered an advantage of the assessment of the viability as well. TEM observation of sections of the testis and cauda epididymidis also revealed ODF extrusion, as seen in the transverse sections of sperm flagella missing one or more ODFs and the associated axonemal microtubule doublets. In a few such sections, the extruded elements were seen in the cytoplasm, outside the mitochondrial sheath or peripheral sheath. Marginal to severe mitochondrial pathologies were observed in the spermatozoa and elongated spermatids, suggesting a link between AFB1-induced sperm mitochondrial pathology and extrusion of ODFs. However, the possibility that AFB1 treatment would disrupt the cytoskeletal proteins of the flagellum, resulting in the extrusion of ODFs, cannot be excluded. This sperm abnormality is reported for the first time as produced by a dietary toxin. Dietary aflatoxins, therefore, could also be contributory factors for the deterioration of the reproductive health of men.

Scrotal heat stress effects on sperm viability, sperm DNA integrity, and the offspring sex ratio in mice

Evidence exists to suggest detrimental effects of heat stress on male fertility. This study was designed to assess the effects of scrotal heat stress on mature and developing sperm in a mouse model. After receiving shock heat treatment (42 degrees C for 30 min), mature spermatozoa were recovered from the epididymis hours (6) or Days (7, 14, 21, 28, 60) later, to determine the variables: number of spermatozoa, sperm viability, motility and progressive motility, sperm DNA integrity as established by the TUNEL method, embryo implantation rate, and sex ratio of the fetuses conceived using the heat-exposed spermatozoa. Our results indicate that transient mild heat treatment does not affect in the same way the different types of male germ cells. Spermatocytes present within the testis at the time of heat stress resulted into a lower concentration of spermatozoa with reduced viability and low motility. Even though, DNA integrity of spermatozoa resulting from spermatocytes was also compromised by heat stress, the higher degree of DNA damage was found among spermatozoa resulting from spermatids present within the testis at the time of heat stress. At last, heat shock effect on spermatozoa present in the epididymis at the time of thermal stress resulted into a sex ratio distortion. These findings point to a higher sensitivity of spermatocytes to heat exposure and also suggest a different response of X and Y chromosome-bearing spermatozoa to heat stress that warrants further investigation.

In vivo spermatotoxic effect of chromium as reflected in the epididymal epithelial principal cells, basal cells, and intraepithelial macrophages of a nonhuman primate (Macaca radiata Geoffroy)

OBJECTIVE

To understand, through a simulation experiment in a nonhuman primate model, the potential in vivo spermatotoxic toxic effect of hexavalent chromium (CrVI) in men who are occupationally or environmentally exposed to it.

DESIGN

Controlled laboratory study.

SETTING

Research laboratory in a department of endocrinology in a university in India.

ANIMAL(S)

Male bonnet monkey, Macaca radiata Geoffroy.

INTERVENTION(S)

Monkeys were exposed ad libitum to 100, 200, and 400 ppm CrVI, dissolved in drinking water, for a chronic period of 180 days.

MAIN OUTCOME MEASURE(S)

Examination of epididymis with a transmission electron microscope and assessment of the effect of CrVI in terms of accumulation of sperm-derived lipofuscin (LF) material in the principal cells, basal cells, and intraepithelial macrophages of the epithelium.

RESULT(S)

The abundance of basal cells and intraepithelial macrophages and the content of LF material in these cell types increased. The principal cells phagocytosed from the lumen the dead sperm resulting from CrVI exposure and processed them partially into LF material, which was acquired by the basal cells and intraepithelial macrophages and processed further. The LF material-laden basal cells and intraepithelial macrophages appeared to leave the epithelium, accompanied by recruitment of fresh basal cells and intraepithelial macrophages.

CONCLUSION(S)

Occupational or environmental exposure to CrVI, as would occur in the tannery, soap, and other industries in developing and underdeveloped countries, can be toxic in vivo to spermatozoa.

Neonatal treatment of rats with diethylstilboestrol (DES) induces stromal-epithelial abnormalities of the vas deferens and cauda epididymis in adulthood following delayed basal cell development

This study investigated whether transient, neonatal (days 2-12) treatment of rats with the potent oestrogen, diethylstilboestrol (DES), altered the structure of the cauda epididymis/vas deferens in adulthood, and if the changes observed related to altered development of basal cells in early puberty. Neonatal treatment with 10 microg DES resulted in the following during adulthood: (a) coiling of the normally straight initial vas deferens, (b) gross epithelial abnormalities, (c) 4-fold widening of the periductal non-muscle layer, (d) infiltration of immune cells across the epithelium into the lumen, and (e) reduction/absence of sperm from the vas deferens lumen. Amongst affected animals>75% exhibited reduced epithelial immunoexpression of androgen receptor and aberrant oestrogen receptor-alpha immunoexpression and 63% exhibited multi-layering of basal cells coincident with increased epithelial cell proliferation. None of the aforementioned changes occurred in rats treated neonatally with 0.1 microg DES. As basal cells play a key role in the development of epithelia such as that in the epididymis and vas deferens, we went on to investigate if neonatal DES treatment affected basal cell development. In controls, basal cells were first evident at day 10 (vas deferens) or day 18 (cauda). Rats treated with 10 microg, but not those treated with 0.1 microg, DES, showed approximately 90% reduction (P<0.001) in basal cell numbers at day 15 and day 18. This decrease coincided with gross suppression of testosterone levels; co-treatment of rats with 10 microg DES+testosterone maintained basal cell numbers at control levels at day 18. However, suppression of testosterone production (GnRH antagonist treatment) or action (flutamide treatment) did not alter basal cell numbers. It is concluded that neonatal exposure to high oestrogen levels coincident with reduced testosterone action results in abnormal changes in the adult cauda/vas deferens that are preceded by delayed differentiation of basal cells. These findings imply a role for androgens and oestrogens in basal cell development and suggest that this may be pivotal in determining normal epithelial (and stromal) development of the cauda/vas deferens.

Impact of a mild scrotal heat stress on DNA integrity in murine spermatozoa

An increase in scrotal temperature can lead to the production of poor quality spermatozoa and infertility. In the present study we have used mice to examine the impact of mild, scrotal heat stress (42 °C for 30 min) on numbers of spermatozoa as well as on the integrity of their DNA. Spermatozoa recovered from the epididymides hours (1 to 24) or days (7 to 32) after treatment were analysed using COMET and sperm chromatin structure (SCSA) assays. The treatment induced a stress response in both the testis and the epididymis that was associated with reduced expression of the cold inducible RNA binding protein (Cirp) and an increase in germ cell apoptosis (Apotag positive cells). Although spermatozoa present in the epididymis at the time of heating contained correctly packaged DNA, its integrity was compromised by heat stress. In addition, although some germ cells, which were present within the testis at the time of heat stress, were removed by apoptosis, many germ cells completed their development and were recovered as motile spermatozoa with damaged DNA. In conclusion, these data demonstrate that scrotal heat stress can compromise the DNA integrity of spermatozoa and this may have clinical implications for patients undergoing IVF and intra-cytoplasmic sperm injection (ICSI).

Ultrastructural evidence for secretion from the epithelium of ampulla ductus deferentis of the fan-throated lizardSitana ponticeriana Cuvier

Among reptiles, an ampulla ductus deferentis has been reported only in Squamata. Fairly detailed studies are available only for two species, the lizard Calotes versicolor (Fam: Agamidae) and the snake Seminatrix pygaea (Fam: Colubridae). The light microscopic study on C. versicolor revealed the ampulla to be a prominent organ, whereas the light and transmission electron microscopic study in S. pygaea revealed it to be discernable only in histological preparations. Further, the epithelium of the ductal portion of vas deferens as well as the ampulla of C. versicolor appears to contribute to the seminal plasma and can also phagocytose dead sperm, whereas in S. pygaea neither of these roles has been established. Thus, we hypothesize that there may be variations in the anatomy, histology, and the role of the vas deferens in general, and the ampulla in particular, of the squamate reptiles. In this study, the ductus deferens of the small fan-throated lizard Sitana ponticeriana (Fam: Agamidae) was subjected to light and transmission electron microscopic analysis. In this lizard the ampulla is more prominent than in C. versicolor. The epithelium of the ductal portion of vas deferens consists of principal cells (with features reflecting roles in endocytosis and phagocytosis of dead sperm), dark cells (which are absent in the epithelium of the ductal portion of vas deferens of snakes), and basal cells. The ampulla of S. ponticeriana is differentiated into storage and glandular portions. The epithelium of the storage portion is like that in the ductal portion of the vas deferens, whereas that of the glandular portion, consisting of dark and light principal cells and foamy cells, is tall and forms into smooth villous folds. All three cell types show evidence for a role in secretion, in all likelihood different from each other, for release into the lumen to contribute to seminal plasma. These cells do not provide evidence of a role in phagocytosis of dead sperm. It appears that within the Squamata, the ductal ampulla differs in structure as well as function. We suggest that the ductal ampulla of agamid lizards is a composite gland of the ampulla ductus deferentis and seminal vesicles of mammals.

Secretory and basal cells of the epithelium of the tubular glands in the male Mullerian gland of the caecilianUraeotyphlus narayani (Amphibia: Gymnophiona)

Caecilians are exceptional among the vertebrates in that males retain the Mullerian duct as a functional glandular structure. The Mullerian gland on each side is formed from a large number of tubular glands connecting to a central duct, which either connects to the urogenital duct or opens directly into the cloaca. The Mullerian gland is believed to secrete a substance to be added to the sperm during ejaculation. Thus, the Mullerian gland could function as a male accessory reproductive gland. Recently, we described the male Mullerian gland of Uraeotyphlus narayani using light and transmission electron microscopy (TEM) and histochemistry. The present TEM study reports that the secretory cells of both the tubular and basal portions of the tubular glands of the male Mullerian gland of this caecilian produce secretion granules in the same manner as do other glandular epithelial cells. The secretion granules are released in the form of structured granules into the lumen of the tubular glands, and such granules are traceable to the lumen of the central duct of the Mullerian gland. This is comparable to the situation prevailing in the epididymal epithelium of several reptiles. In the secretory cells of the basal portion of the tubular glands, mitochondria are intimately associated with fabrication of the secretion granules. The structural and functional organization of the epithelium of the basal portion of the tubular glands is complicated by the presence of basal cells. This study suggests the origin of the basal cells from peritubular tissue leukocytes. The study also indicates a role for the basal cells in acquiring secretion granules from the neighboring secretory cells and processing them into lipofuscin material in the context of regression of the Mullerian gland during the period of reproductive quiescence. In these respects the basal cells match those in the epithelial lining of the epididymis of amniotes.

Microcanalization in the epididymis to overcome ductal obstruction caused by chronic exposure to chromium – a study in the mature bonnet monkey (Macaca radiata Geoffroy)

In order to apprehend the toxic effects of chromium, an occupational/environmental pollutant, on the epididymis, adult bonnet monkeys were exposed to chromium (VI) in their drinking water at concentrations of 100, 200 and 400 p.p.m. for a chronic period of 180 days. At the end of the experimental period, testicles and segments of epididymis from control and treated monkeys were subjected to light microscopic (resin-embedded semi-thin sections) and transmission electron microscopic analyses. Among the various changes undergone by the epididymal epithelium, the present paper describes the origin of two different kinds of microcanals, probably caused by ductal obstruction. The first type of microcanal, which appears to provide passage for spermatozoa to bypass the obstructed main duct, is comparable with the one already reported in carbendazim-treated efferent ductules of the rat. The second type of microcanal, which is novel, consisted of a lumen in the epithelium enclosed by four to five cells, which are either modified basal cells, principal cells or a hitherto unknown cell type. This novel type of microcanal is suggested to be a device to entrap the spermatozoa which reach the core of the epithelium and may be a mechanism to prevent extravasation of sperm so as to avoid an autoimmune response of spermatic granuloma formation. Thus, the present study has shown that chronic exposure to chromium (VI) through drinking water can produce pathological manifestations in the epididymal epithelium but the epididymis, being a versatile organ, is capable of overcoming such adverse situations through novel devices.