Synaptic junctions. Color enhanced SEM showing the junctions (synapses) of motor nerves in the marine snail Aplysia. At center is a nerve cell body; clustered around are branches of motor neuron axons with small terminal swellings (called boutons or motor end plates). These swellings attach to the tissue surface and synapse with the cell body. They release neurotransmitter chemicals in response to electrical impulses traveling down the nerves. In this way nerve to nerve communication occurs, and the nerve cell body responds. Aplysia is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are one clade of large sea slugs, marine gastropod mollusks. The large nerves in the snail Aplysia make it ideal for such studies. Magnification @ x700 at 35 mm size.