Later in development, when dendrites mature, transport of carriers for dendritic cell surface proteins becomes highly selective. Dendritic carriers, pseudo-colored in green, are seen traveling bi-directionally in the dendritic branch, identified retrospectively by the presence of a dendritic marker, MAP2, pseudo-colored in red. No carriers enter the axon.
Time lapse: 30 seconds (one loop of movie)
fusion.mov (1.0mb)
Delivery of membrane proteins to the cell surface occurs by fusion of the carriers with the plasma membrane. Two fusion events have been captured fortuitously in this movie. Upon fusion, the contents of the carriers very rapidly diffuse in the plasma membrane, resulting in a fleeting impression of a railroad track due to the optical sectioning power of the microscope.
Time lapse: 30 seconds (one loop of movie)