Fig. 5.

Basal rate of exo-endocytosis is downregulated after contact with a postsynaptic cell. A–C, Synaptic vesicle exo-endocytosis occurs at different basal rates, in distinct compartments of a same 14-d-old neuron grown in a microisland, depending on the contact with the postsynaptic target. An efficient internalization of Syt-ecto Abs takes place in basal conditions in the isolated axon (C, large arrowhead) but not at autaptic contacts (C, small arrowheads) of the same neuron, shown as a bright field in A. B, Double immunolabeling of the same neuron for the synaptic vesicle protein SV2. Scale bar, 18.75 μm.