Tissue and Cell Specificity of Immobilin Biosynthesis1

Ruiz-Bravo, Norka

doi:10.1095/biolreprod39.4.901

Cited by 19 publications

(20 citation statements)

References 12 publications

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“…In the corpus and cauda regions, principal cells were unreactive. These observations extended the preliminary results obtained by Ruiz-Bravo (1988).…”

Section: Introductionsupporting

confidence: 91%

Developmental expression of immobilin in the rat epididymis

1994

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“…In the corpus and cauda regions, principal cells were unreactive. These observations extended the preliminary results obtained by Ruiz-Bravo (1988).…”

Section: Introductionsupporting

confidence: 91%

Developmental expression of immobilin in the rat epididymis

1994

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“…The present study extends the light microscope immunofluorescent findings of Ruiz-Bravo (1988) on the localization of immobilin to a more complete analysis of all regions of the extratesticular duct system. Using light and electron microscope immunocytochemistry we have investigated the role the different epithelial cells play with respect to immobilin.…”

Section: Discussionsupporting

confidence: 59%

Epithelial cells of the epididymis show regional variations with respect to the secretion or endocytosis of immobilin as revealed by light and electron microscope immunocytochemistry

1992

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The localization of immobilin, a glycoprotein known to be present and to immobilize spermatozoa in the lumen of the epididymis, was investigated using light and electron microscope immunocytochemistry. In the light microscope, a distinct immunoperoxidase reaction product was observed in the lumen over the brush border of the epithelial nonciliated cells of the efferent ducts, while only a faint reaction was seen over their supranuclear region. In the proximal area of the initial segment of the epididymis no immunoperoxidase staining was observed either over epithelial cells or in the lumen. In the middle area of the initial segment, several epithelial principal cells became intensely immunostained but the majority were unstained; a weak reaction appeared in the lumen. In the distal area of the initial segment, more principal cells became immunostained, and while some were intensely reactive, others were moderately or weakly stained or unreactive. In the intermediate zone and proximal caput epididymidis, the principal cells showed the maximal immunoreactivity with all principal cells being reactive; staining in the lumen also reached its maximal reactivity in these areas. Immunostaining of principal cells gradually decreased along the epididymal duct and disappeared in the cauda epididymidis, however, an intense reaction persisted in the lumen. In the distal area of the cauda epididymidis, clear cells were reactive. In the electron microscope, immunogold labeling of reactive principal cells of the middle and distal areas of the initial segment, intermediate zone, and caput epididymidis was detected over cisternae of endoplasmic reticulum, stacks of Golgi saccules, and spherical electron lucent (200-400 nm in diameter) vesicles. The latter were present on the trans face of the Golgi stack, in the vicinity of th Golgi apparatus, and close to the apical cell surface; they are considered as secretory vesicles involved in the secretion of immobilin. In the distal area of the cauda epididymidis, epithelial clear cells showed an intense immunogold labeling over their endocytic apparatus. Immunogold labeling in the lumen of the epididymis was found over a fine flocculent material dispersed between the sperm. This material was especially abundant in the cauda epididymidis and did not appear to be bound to the surface of the sperm. The present results suggest that principal cells of the epididymis are involved in the secretion of immobilin, but that a differential secretory pattern exists between epididymal segments with maximal secretory activity occurring in the intermediate zone and proximal caput epididymidis, while no secretion takes place in the cauda epididymidis. Excess immobilin appears to be endocytosed for degradation by clear cells of the cauda epididymidis.

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“…Efferent duct ligation and unilateral orchidectomy both result in a dramatic decrease in epididymal Sa-reductase activity, especially in the proximal portion of the tissue (Robaire et al, 1977;Robaire, 1979). Thus, in the initial segment, epididymal Sa-reductase activity is regulated in a paracrine manner by a substance directly entering the epididymis via the efferent ducts, and not via the general circulation ; this type of regulation has also been noted for immobilin (Ruiz-Bravo, 1988), CRES (Cornwall et al, 1992), and gamma-glutamyl transpeptidase (Palladino and Hinton, 1994) and has been termed as "lumincrine" by Hinton's group . Based on the results of a series of endocrine manipulations that altered the nature of the substance( s) entering the epididymis from the testis via the efferent ducts Robaire and Zirkin, 1981;Robaire and Viger, 199S), it can be shown that the paracrine factor regulating nuclear epididymal Sa-reductase activity is of Sertoli cell origin and under the control of testosterone.…”

Section: Regulation Of Epididymal Sa-reductasesmentioning

confidence: 73%

“…A characteristic checkerboard-like pattern can be seen for epididymal principal cells after immunolocalization of a number of gene products such as immobilin (Ruiz-Bravo, 1988, Hermo et a!., 1992b, clusterin (SGP-2, Hermo et a!., 1991), and mouse epididymal protein 9 (Rankin et a!., 1992). Normally, either at the point in the duct where immunostaining first appears or when the signal stops being expressed there are, in a given cross section, some cells that are intensely stained while others remain unreactive.…”

Section: Epithelial Proteinsmentioning

confidence: 99%