Fusion of macropinosomes and tubular endolysosomes. (bottom and top right) Time-lapse video of macrophage stimulated with M-CSF and LY (bottom right, inverted contrast) after preloading endolysosomes with TRDx (top right, inverted contrast). (top left) Phase contrast. (top middle) Phase contrast with blue overlay of TRDx fluorescence. (bottom middle) LY/TRDx fluorescence ratio image. Bright spots indicate LY-labeled macropinosomes. Black indicates relative distribution of TRDx-labeled endolysosomes. (bottom left) Phase contrast with blue overlay indicating TRDx fluorescence and red overlay indicating LY fluorescence. Macropinosomes were wrapped by tubular endolysosomes before disappearing into the endolysosomal compartment. Frame intervals = 20 s.
