Neuronal growth cones: specific interactions mediated by filopodial insertion and induction of coated vesicles

We are interested in the factors that guide individual neuronal growth cones during embryonic development. Here we report on the discovery of a highly specific interaction between developing growth cones in the grasshopper embryo as revealed by transmission electron microscope serial-section reconstructions. Numerous filopodia from an identified growth cone (MP1) insert deep within another identified growth cone (pCC), inducing the formation of coated pits and vesicles. This interaction is highly specific, since filopodia from other nearby growth cones that contact the surface of the two interacting neurons neither penetrate them nor induce coated vesicles. These specific filopodial interactions may play an important role in the subsequent development of these neurons.