Movie 1 shows a Dictyostelium cell taking up fluorescently-labeled dextran (red) by macropinocytosis. The size of the macropinosome decreases and its contents grow more concentrated during the 5-minute interval of the movie.

In Movie 2, cells were first placed in nutrient medium containing green fluorescent dextran for 17 minutes, then shifted to medium containing red fluorescent dextran. The movie shows a new red macropinosome meeting and fusing with an older green endosome about 80 seconds after uptake, producing an orange compartment with mixed content.

The orange endosomes are extremely dynamic and pleiomorphic, as shown in Movie 3, recorded about 10 minutes later. These movies were made using a Zeiss LSM410 confocal microscope.

Movies 4 and 5 show that endosome dynamics are microtubule-based. In these cells, microtubules were labeled with GFP and endosomes with a styryl dye. Microtubules exhibit a constant undulatory motion that brings them into contact with endosomes, which are then transported along the microtubules.

Movies 4 and 5 were made using a Solamere video camera and an Olympus microscope equipped for total internal reflection fluorescence microscopy; the movies are shown in real time (30 frames per second).