DGs originate from late endocytic structures. (A) DGs were labeled with the green fluorescent dye mepacrine in live MEG-01 cells expressing VMAT2-Cherry and visualized by spinning-disk confocal microscopy. The inset shows examples of colocalization between the 2 DG markers; 94% ± 2% of 171 mepacrine structures (7 cells) also contain VMAT-Cherry. (B) Live MEG-01 cells were allowed to internalize the fluid phase marker dextran Alexa Fluor 647, and DGs were subsequently labeled with mepacrine. Cells were observed by spinning-disk confocal fluorescence microscopy. Examples of structures containing both markers are presented in the magnified inset (MOC = 0.43 ± 0.04, n = 6 cells). (C) Live MEG-01 cells expressing the DG marker VMAT2-GFP were labeled with dextran Alexa Fluor 647 and imaged by spinning-disk confocal fluorescence microscopy. Inset: Examples of VMAT-GFP presence in the limiting membrane of organelles containing dextran Alexa Fluor 647 in the lumen; 66% ± 8% of 187 structures containing fluorescent dextran (7 cells) also contain VMAT-GFP. Bars represent 5 μm.