Four-dimensional (4D) imaging is utilized to study the behavior and interactions among two types of endosomes in living vertebrate nerve terminals. Movement of these small structures is characterized in three dimensions, permitting confirmation of events such as endosome fusion and exocytosis.
Stewart, R. S., Kiss, I. M., Wilkinson, R. S. Visualization of Endosome Dynamics in Living Nerve Terminals with Four-dimensional Fluorescence Imaging. J. Vis. Exp. (86), e51477, doi:10.3791/51477 (2014).