Expression of Occludin in Testis and Epididymis of Wild Rabbits, Lepus sinensis coreanus

Abstract

Tight junctions (TJs) in inter-Sertoli junctional areas and epididymal epithelia build up the blood-testis barrier (BTB) and the blood-epididymal barrier (BEB), respectively. In this study, the expression of occludin, an integral member of the TJs, was examined in testis and different regions of epididymis of Lepus sinensis coreanus, an Korean wild rabbit species. In testis, intense occludin immunoreactivity was found in the basally located inter-Sertoli junctional area together with diffused immunoreactivity of occludin in the cytoplasm of Sertoli cells. It can be suggested that occludin is one of the robust elements of BTB in seminiferous tubules of rabbit testis. In proximal and distal caput epididymis, occludin immunoreactivity was found in the lateral as well as apical contacts of epithelial cells. In corpus epididymis, intense occludin immunoreactivity was found in the basolateral as well as apical contacts of epithelial cells together with cytoplasmic signal. In cauda epididymis, occludin immunoreactivity in luminal epithelia was relatively strong but largely found in the cytoplasm. This suggests that intriguing regulatory mechanisms differentially recruit occludin to the TJ in the different regions of epididymal epithelia. The differences in the subcellular localization as well as expression levels of occludin among the epididymal segments may reflect differential paracellular permeability of epithelia along the epididymal tubules and be correlated with sperm maturation in rabbit. In Western blot, a major form of occludin was MW 62 kDa together with small fragments of MW 34-39 kDa in testis and epididymis, suggesting the peptide cleavage of occludin. This is the first report on the molecular nature of TJs in a wild rabbit testis and epididymis.

Effect of local scrotal heating on the expression of tight junction‐associated molecule Occludin in boar testes

“…The immunohistochemistry results of the present study were similar to previous observations in Gye (), Yoon et al. () and Cai et al. ().…”

“…Our results for Occludin (both mRNA and protein) were similar with these findings (Chen et al., ; Cai et al., ; Liu & Li, ). Furthermore, previous studies confirmed that immunoreactivity of Occludin was found in the cytoplasm of Sertoli cells and localized at tight junctions strands in dog and rabbit testes (Gye, ; Yoon, Park, Nah, & Gye, ). Cai et al.…”

Blood-testis barrier and spermatogenesis: lessons from genetically-modified mice

“…By postnatal day 23 and in adult mice, these bands are present in all tubules at all stages of seminiferous epithelial cycle 97. As in mice, Ocln is also detected at all stages of the seminiferous epithelial cycle in dogs and Korean wild rabbits Lepus coreanus 9899. However, in rats, Ocln protein expression is stage-specific, expressing heavily in Sertoli cells in seminiferous tubes of all stages except stage VIII, where it is not detectable by immunostaining 9699.…”

“…However, in rats, Ocln protein expression is stage-specific, expressing heavily in Sertoli cells in seminiferous tubes of all stages except stage VIII, where it is not detectable by immunostaining 9699. Interestingly, Ocln is not expressed in seminiferous tubules of guinea pigs (Cavia porcellus) and humans 9599…”

Postnatal Changes in the Expression of Claudin‐11 in the Testes and Excurrent Ducts of the Domestic Rabbit (Oryctolagus cuniculus domesticus)

“…To date, several TJ proteins have been identified in the mammalian testis and epididymis (Moroi et al, 1998; Gow et al, 1999; Morita et al, 1999; Hellani et al, 2000; Gye, 2003a,b, 2004; Guan et al, 2005; Gregory and Cyr, 2006; Dubé et al, 2007; Yoon et al, 2009). Of these genes, the CLDN family of transmembrane proteins accounts for at least 24 members, the genes of which are expressed in a tissue‐specific manner (Van Itallie and Anderson, 2006).…”