MEG-01 cells have DGs that can be studied by different microscopy techniques. (A) Model depicting the protein traffic to DG. DG transmembrane proteins (gold) follow the secretory pathway through the Golgi complex to early endosomes where they are selectively targeted to maturing DGs originated from MVBs. (B) Thin-section transmission electron microscopy image of a MEG-01 cell subjected to HPF, fixed or embedded with glutaraldehyde-uranyl acetate-Lowicryl HM20. Original magnification, ×3900 (bar represents 500 nm). (C) Spinning-disk confocal fluorescence microscopy images of a MEG-01 cell fixed and immunostained with LAMP2 and MRP4 antibodies to label DGs (MOC = 0.63 ± 0.06, n = 5 cells). Bar represents 10 μm. (D) Spinning-disk confocal fluorescence microscopy images of a live MEG-01 cell expressing the DG markers VMAT2-Cherry and LAMP2-GFP (MOC = 0.58 ± 0.03, n = 10 cells). Bar represents 5 μm. PM indicates plasma membrane; and IDG, immature dense granule.