Figure 3.

(A) In normal spermatogenesis, ISH revealed a strong signal for Cx43 mRNA around the nuclei of Sertoli cells (transparent arrows), spermatogonia (transparent arrowhead), and primary spermatocytes (black arrow). Note an immunonegative spermatogonia (black arrowhead) and immunonegative round spermatids (white arrow). Seminiferous tubules from mouse testis with normal spermatogenesis used as positive control showed an identical expression pattern (inset). CIS-only tubules displayed a heterogeneous expression pattern of Cx43 mRNA. In very few tubules, a hybridization signal was mainly present in the cytoplasm of Sertoli cells (CIS cells are marked with a uniform line; Sertoli cell nuclei: transparent arrows, B). However, in most tubules the signal in Sertoli cells was either markedly reduced or completely absent (C and D). A strong signal was detectable in the cytoplasm of peritubular cells (white arrowheads, C) and in endothelial cells of small blood vessels (curved black arrow, D). In seminoma, only single cell clusters (E), single cells (curved transparent arrows, F), and/or endothelial cells (F, inset b) were found to express Cx43 mRNA, whereas seminoma cells showed no hybridization signal for Cx43. Control incubations with Cx43 cRNA sense probes were in all cases completely negative (B, inset, and F, inset a). Scale bars = 50 µm.