Tubulobulbar Complexes Formed In Sertoli Cells In Primary Cultures Associate With Intercellular Junction Elements

Abstract

In the seminiferous epithelium, unique double membrane structures termed tubulobulbar complexes (TBCs) develop in association with basal junction complexes. These actin‐related structures are proposed to internalize intercellular junctions during the movement of spermatocytes from basal to adluminal compartments of the epithelium. To study the role of basal TBCs in junction turnover, we use a primary Sertoli cell culture system in which TBCs develop in the vicinity of junction complexes between Sertoli cells. We immunoprobed cultured Sertoli cells for the intercellular junction elements Claudin‐11, Connexin‐43 and Nectin‐2 and discovered rod‐like structures that protrude into Sertoli cells from the cell periphery. These protrusions resemble TBCs that form in the intact seminiferous epithelium. These protrusions also co‐localize with F‐actin, which is known to associate with the proximal tubular part of TBCs and can be used as a marker for TBCs. Significantly, cultured Sertoli cells that express GFP‐tagged Claudin‐11 and Connexin‐43 extend similar protrusions into neighboring non‐transfected Sertoli cells. Our results are consistent both with the conclusion that junction elements from neighboring Sertoli cells are found together within TBCs, and with the hypothesis that tubulobulbar complexes may play a role in the turnover of intercellular junctions. Supported by an NSERC Discovery Grant to AWV.Grant Funding Source : NSERC