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

Abstract

We examined the expression of claudin-11 (CLDN11)in the testes and male reproductive tracts of rabbits. The rabbitCLDN11 cDNA sequences were nearly identical with human, mouse,and bovine CLDN11. The levels of CLDN11 mRNA and protein(22 kDa) we re mar kedl y inc re ased i n the te stis d uri ng ad ultdevelopment. On postnatal day (PND) 10, CLDN11 was colocalizedwith ZO-1 at the lateral contacts between adjacent Sertoli cells andwas perpendicular to the basal lamina. In adult testis on PND 180,CLDN11 was codistributed with ZO1, and the pattern of immunore-activity consisted of wavy linear tracts parallel to the basal lamina,which was different according to the spermatogenic stage. Theseresults suggest that CLDN11 participates in inter–Sertoli cell tightjunctions (TJs) at the blood-testis barrier in adult rabbits. CLDN11 wasalso found in the basal regions of Sertoli cells adjacent to the basallamina in adult testis, suggesting that CLDN11 also participates in theadhesion between Sertoli cells and the basal lamina. CLDN11 mRNAand protein expressions were decreased in the adult epididymiscompared with those in immature animals. In adults, CLDN11 mRNAlevels were relatively high in the efferent duct, followed by those in thevas deferens, proximal corpus, and distal cauda, although low levelswere observed in the initial segment and caput. On PND 10, CLDN11immunoreactivity was identified at the apicolateral contacts betweenadjacent epithelial cells in the epididymis and vas deferens. In adults,CLDN11 was found in the nonciliated cells in the efferent duct and atthe lateral contacts in the epithelial cells in the epididymal segments.In the caput, CLDN11 was found at the apicolateral contacts betweenadjacent epithelial cells, but expression was weak to negligible in thecorpus of the vas deferens. CLDN11 may play an important role in TJsand cell adhesion in immature rabbit excurrent duct epithelia. In adultrabbits, CLDN11 in efferent duct epithelium and epididymal epitheliummay contribute to the specific environment for sperm maturation