Fig. 4. Sdmg1 is localised to endosomes in Sertoli cells. (A) Immunostaining shows Sdmg1 is perinuclear in undifferentiated (undiff) SK11 Sertoli cells grown at 33°C. (B) Sdmg1 is present in perinuclear and peripheral clusters (arrow) in differentiating (diff) SK11 Sertoli cells grown at 39.5°C for 1 day. (C) The peripheral clusters (arrows) of Sdmg1 staining are localised to actin-poor parts of the cell. (D-H) Trans-Golgi network markers Vamp4 and Stx16, and endosomal markers Vti1b, Vamp7 and Stx7 all have a perinuclear distribution in differentiating SK11 Sertoli cells. (I-L) The recycling endosome marker Tfrc, and the Vamp3, Vamp8 and Stx3 SNAREs associated with secretory granules all exhibit peripheral clusters of punctate staining (arrows) in differentiating SK11 Sertoli cells. DNA is shown in blue. Scale bar: 10 µm. (M-P) ImmunoEM for Sdmg1 (10 nm gold particles) in differentiating SK11 Sertoli cells (M,N) and 13.5 dpc Sertoli cells (O,P). Sdmg1 is localised to the limiting membrane of early endosomes (ee) and multivesicular bodies (mvb), and is often associated with an electron-dense region of the limiting membrane (arrowhead). Sdmg1 is also present on tubulo-vesicular membranes (M, arrow in P). Scale bars: 100 nm.