Characterization of testes gap junctions
Localization of the connexins (Cx) that assemble into the gap junctions of the rat testis was identified through immunofluorescence and immunogold electron microscopy. Five connexins (Cx43, Cx37, Cx33, Cx32, Cx26) were assembled depending upon the cell type, the developmental age and the stage of the seminiferous epithelium. Cx43 was localized to a number of different cells in the testes: Sertoli cells, peritubular cells, Leydig cells and macrophages. Assembly of Cx33 into gap junctions was limited to the Sertoli cells. Gap junctions consisting of a mixture of both Cx43 and Cx33 were identified on Sertoli membranes. Only Cx43 gap junctions were identified between Leydig cells. In the interstitium only the endothelial cells were found to contain Cx37. Cx32 and Cx26 were found in germ cells of both the immature and mature testes. Cx32 was also detected between Sertoli cells and between Sertoli and germ cells in disaggregated tissue. Differential assembly of Cx43 and Cx33 was observed in the immature testes. Cx33 was detected after 15 days postnatal, whereas Cx43 was present as early as 5 days postnatal. The surface and cytoplasmic distribution of Cx43 and Cx33 in these immature testes eventually became localized to the Sertoli occluding junctions at about 28-34 days postnatal. By 60 days postnatal, the distribution of Cx43 and Cx33 became stage-dependent. Tubules consisting of stages II-VII were strongly immunofluorescent and stages IX-XIV were weakly immunofluorescent for both Cx43 and Cx33. Dye-coupling experiments demonstrated functional coupling between Leydig cells and between peritubular cells. Coupling experiments using the tracers, Lucifer yellow, neurobiotin and propidium iodide demonstrated that between cells of the seminiferous epithelium, tracers were selectively transferred. This selectivity is believed to be dependent upon the type of gap junction formed and on the properties of the tracers. This thesis shows that the rat testis contains gap junctions composed of different connexins. This creates unique gap junction-mediated communication compartments which may be regulated independently by growth factors and reproductive hormones. ^
Ignatius P Tan,
"Characterization of testes gap junctions"
(January 1, 1997).
ETD Collection for Fordham University.