摘要:

AbstractGlutathione S‐transferases (GSTs) are dimeric proteins that come from a multigene family. They can be grouped into five classes (alpha, mu, pi, sigma, theta) based on the degree of amino acid homology of their subunits. These GST isozymes are able to catalyze the conjugation of glutathione with a wide variety of electrophiles, thereby protecting important cellular constituents from electrophilic attack. In the present study, the distribution of the Ya and Yc subunits from the alpha family, as well as the Yb1and Yb2subunits from the mu gene family was examined using immunocytochemistry in the adult rat testis and epididymis. The results of these four GST subunits were also compared with two other subunits, the Yf and Yo proteins, which have already been investigated in our laboratory [Veri et al. (1993), J. Androl., 14:23–44; Veri et al. (in press), J. Androl.]. In the testis, Leydig cells were intensely stained for all six subunits. Within the seminiferous epithelium, Sertoli cells were reactive only for antibodies raised against the Ya, Yb1and Yf subunits. Among germ cells, all spermatogonia, spermatocytes and step 1–15 spermatids were virtually unreactive for each of the six GSTs. However, moderate to intense staining was seen over steps 16–19 spermatids with the anti‐Yo and anti‐Ya antibodies, and intense staining over step 19 spermatids with the anti‐Yb1, and anti‐Yb2antibodies. In the rete testis, Yf, Yo, Yb1, and Yb2subunits were intensely reactive over the epithelial cells with weak staining for Yc and no staining for Ya antibodies. Interestingly, in the efferent ducts the Yc, Yb1, and Yf proteins were intensely reactive over ciliated cells, whereas only the Yc protein was intensely reactive over nonciliated cells. In the epididymis, immunoreactivity varied among the principal and basal cells of a given epididymal region for each GST antibody. In the case of principal cells, several of the GSTs showed a similar immunostaining pattern along the tubule. Although not identical in intensity of reaction, the Yc, Yb1, Ya and Yo proteins showed an increase in staining intensity from the proximal to distal segments of the epididymis. In contrast, the Yb2protein was intensely expressed only in the distal caput with weak levels throughout the rest of the epididymis. The Yf reactivity was strongest from the distal initial segment to the distal caput and unreactive in the corpus and proximal cauda epididymidis. In the case of the Yb2subunit, reactivity was more intense over the nucleus of principal cells than the cytoplasm in the proximal cauda epididymidis. Similar results were seen for Yb1protein over principal cells from the middle region of the initial segment to the proximal caput. In the distal caput, principal cells displayed a checkerboard‐like staining pattern with the Yb1, and Yf proteins. A population of apically located cells of the proximal initial segment was intensely reactive with the Yb1, and Yo proteins and of the middle initial segment with the Yf protein. Intense staining was also noted for several GSTs in basal cells. The Yf and Yc proteins were stained in basal cells along the entire length of the epididymis. The Yb1, Ya and Yb2proteins were intensely reactive over basal cells of the corpus epididymidis with weak to no staining in other regions. The Yo protein was negative in basal cells. Clear cells were always unreactive. These results indicate that expression of GST proteins varies considerably along the length of the epididymis. Changes in levels of GST expression in principal and basal cells along the length of the epididymis may result from the need to protect spermatozoa from a changing environment of harmful electrophiles. The results also suggest that expression of the various GSTs is complex and under the control of different regulatory factors. © 19

ISSN:1059-910X    

DOI:10.1002/jemt.1070300102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractIn previous studies we reported the synthesis, secretion, and immunolocalization at the light microscopic level of two mouse epididymal proteins, MEP 7 and MEP 10 [Rankin et al. (1992b), Biol. Reprod., 46:747–766]. MEP 7 is the mouse homologue of the rat metalloproteins, AEG/D and E, and MEP 10 is the mouse homologue of the rat retinoic acid binding proteins, B and C. We now describe the immunolocalization of MEP 7 and MEP 10 in the mouse epididymis at the electron microscopic level. MEP 7 was localized in the Golgi apparatus, in small electron‐lucent secretory vesicles, and on microvilli of the principal cells from the distal caput epididymidis to the cauda. The luminal contents were also immunoreactive in these regions of the epididymis. Although some gold particles were associated with the sperm surface, there was no selective concentration of these particles. In addition, MEP 7 was localized in large (600 nm) supranuclear endocytic vesicles and in infranuclear lysosomes. MEP 10 immunoreactivity was also seen on the microvilli of the principal cells of the distal caput and corpus and the luminal contents from the distal caput to the cauda epididymidis. There was no association of gold particles with the sperm surface. In contrast to MEP 7, there was no detectable MEP 10 immunoreactivity on the organelles of the principal cells involved in protein secretion or endocytosis.Clear cells also demonstrated immunoreactivity to MEP 7 and MEP 10. However, the intensity of immunolabeling, and the number of clear cells labeled, was greater with MEP 10 than MEP 7. In the case of MEP 7, the gold particles were located on the large supranuclear endocytic vesicles and on some infranuclear lysosomes, from the proximal corpus to the middle cauda, while in the case of MEP 10, gold particles were predominantly present in infranuclear lysosomes from the distal caput to the middle cauda.These results suggest that the principal cells are involved in both the secretion and endocytosis of MEP 7. The MEP 10 and MEP 7 proteins present in the lumen of the mouse epididymis are endocytosed from the lumen and degraded in the clear cells. However, the process of endocytosis by the clear cells of these two proteins appears to be different. © 1995 Wiley‐Lis

ISSN:1059-910X    

DOI:10.1002/jemt.1070300103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe present study used the freeze‐fracture technique and vascular infusion of horseradish peroxidase (HRP) as a junction permeability tracer, visible in thin sections, to investigate potential seasonal variations in the mink epididymis and vas deferens cell junctions. The junctions were studied in kits during the neonatal period, during and after puberty, and during adulthood monthly throughout the annual reproductive cycle. Results showed the existence, at the time of birth, of a junctional complex joining ductal cells that reached the lumen of the epididymis and vas deferens. The lumenal impermeable segment of the junctional complex was characterized by the presence of an occluding zonule made up of continuous tight junctional ridges extending around the perimeter of the cell. The basal permeable segment of the junctional complex contained mainly discontinuous ridges with frequent forming gap and tight junctions next to adhering junctions. Receding annular junctions were present in the apical and lateral cytoplasm of principal and clear cells. The membrane domain apical to the occluding zonule bore 30–35 nm exo/endocytosis blebs and 40–60 crenations associated with deforming tight and gap junctions made up of randomly scattered particles. Patterns of junctional strands varied greatly from one principal and/or clear cell to another. However, cell junctions did not significantly vary from the neonatal period to adulthood nor from breeding to testicular regression. Anatomical subdivisions of the epididymis with fewer junctional strands per zonule and high diversity in their patterns exhibit no permeability differences to HRP when compared with subdivisions containing more numerous strands. The junctions were impermeable during the neonatal period and throughout the annual reproductive cycle. The following conclusions were reached: (1) a competent occluding zonule developed in the mink epididymis and vas deferens before it did in the testis; (2) the number of strands and the diversity of patterns did not correlate with permeability differences; (3) after the development of a lumen in the testicular excurrent duct, neither receding cellular changes caused by testicular regression nor seasonal passage of a bolus of sperm through the duct modified the occluding zonules; and (4) in the testicular excurrent duct, junction modulation (i.e., formation and deformation) paralleled that in the testis and followed the direction of the synthesis‐transport‐secretion process. © 1995 Wiley

ISSN:1059-910X    

DOI:10.1002/jemt.1070300104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractThe epididymal junctional complex between adjacent principal cells is composed of apically located gap, adherens and tight junctions. Tight junctions between adjacent epithelial cells lead to the formation of the blood‐epididymal barrier. The objectives of this study were to examine the structure of the epididymal junctional complex in the different regions of the epididymis and to review the regulation of epithelial cadherin in the rat epididymis. Changes in the structure of the junctional complex, at the level of the electron microscope, were evident when comparing the initial segment to other regions of the epididymis. In the initial segment, the tight junction spanned a considerable length of the apical plasma membrance but had few desmosomes. In the other regions of the epididymis, the span of merging plasma membranes was considerably reduced, but in these regions, numerous desmosomes were present in the apical region. Several examples of what appeared to be a loss of portions of the plasma membrane of adjacent principal cells were evident along the entire epididymis. Such images as the invagination of a portion of the lateral plasma membrane of one principal cell into another, constriction of the invaginated area and eventual detachment leading to the formation of annular junctions suggest that there is a turnover of plasma membranes.The formation of cellular junctions involves the interactions of cell adhesion proteins followed by the addition of junctional proteins which assemble into tight and gap junctions. Epithelial cadherin (E‐Cad), a calcium‐dependent cell adhesion protein, was localized to the principal cells of the epididymis. Immunocytochemistry at the level of the electron microscope showed that E‐Cad was present between the lateral plasma membranes of adjacent principal cells, both in the region of the junctional complex and in the deeper lying areas. E‐Cad was also present in annular junctions located in close proximity to the junctional complex, indicating that these structures were related to the plasma membrane.E‐Cad mRNA levels are regulated during postnatal epididymal development. In the caput‐corpus epididymidis, E‐Cad mRNA concentrations increase to peak at 42 days of age. This is well correlated with the conversion of testosterone to dihydrotestosterone in the epididymis. In the cauda epididymidis, however, E‐Cad mRNA concentrations do not increase as a function of age, indicating that this protein is regulated in a segment‐specific manner. In addition, the longitudinal distribution of E‐Cad mRNA along the epididymis differs when comparing young rats to 42‐day‐old rats, when serum levels of androgens are high. In the adult, the pattern of E‐Cad mRNA concentrations along the epididymis appears to be dependent on serum androgen levels. A dose‐dependent maintenance of E‐Cad mRNA concentrations was observed throughout the epididymis of orchidectomized rats after replacement with testosterone.Together, these data indicate that the epididymal junctional complex is a dynamic structure which varies along the epididymis; this complex may be renewing itself. The regulation of cell adhesion proteins such as E‐Cad offers a mechanism whereby androgens may regulate the cell‐cell interaction and junctional formation in the rat

ISSN:1059-910X    

DOI:10.1002/jemt.1070300105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractTo understand the process of sperm maturation, an understanding of interactions between the spermatozoa with the luminal fluid microenvironment and with the epididymal epithelium is necessary. The composition of epididymal luminal fluid of several species is well documented but the manner by which the epididymis contributes to the formation of this specialized milieu is not so well understood. A major role played by the epididymis is to finely regulate the movement of molecules into and out of the lumen. This ensures that as spermatozoa progress along the duct they are exposed to a continually changing, but optimal environment necessary for their maturation and survival. This review focusses on our current understanding of the contributions of the epididymal epithelium to the formation of a specialized luminal fluid microenvironment. The role of the blood‐epididymis barrier, the composition of the epididymal luminal fluid, the permeability properties of the epididymal epithelium, and recent studies on a number of luminal fluid proteins and expression of the genes which encode these proteins are discussed. © 1995 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070300106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractCommon principles can be discerned in the response of the epididymis to vasectomy, despite species differences. Increases in the size and number of lysosomes are the most frequent changes in the epididymal epithelium. The presence or absence of additional alterations such as changes in the height of the epithelium may be related to variations in distensibility of the vas deferens and epididymis. Direct measurements by micropuncture of epididymal and seminiferous tubule hydrostatic pressure indicate that, contrary to dogma, increased pressure in the distal epididymis after vasectomy is not generally transmitted to the seminiferous tubules. The epididymal interstitium shows microscopic changes indicative of chronic inflammation, with infiltration of macrophages, lymphocytes, and plasma cells, and rats with these lesions have higher antisperm antibody levels than animals lacking epididymal changes. Macrophages and neutrophils may enter the duct through the epididymal epithelium, at sites of rupture of the duct, and in the efferent ductules. Cyst‐like spermatic granulomas occur in virtually all species where the epididymis or vas deferens ruptures with escape of spermatozoa. The sites and timing of granuloma formation may depend on the mechanical properties of the tract in different species, and they are probably important in the immune response to vasectomy. Postvasectomy sera in Lewis rats recognize a consensus repertoire of dominant autoantigens that closely resembles the antigens bound by sera from rats immunized with isologous spermatozoa. There are multiple routes for disposal of the sperm that continue to be produced after vasectomy. © 1995 Wiley‐Liss,

ISSN:1059-910X    

DOI:10.1002/jemt.1070300107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:1059-910X    

DOI:10.1002/jemt.1070300101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY