Perikaryon-a ganglion is a collection of neuron cell bodies outside of the central nervous system. the cell body of a neuron is called a perikaryon or soma. an astrocyte is a supporting cell seen in the central nervous system. the basophilic clusters of ribosomes and rough endoplasmic seen in neuron cell bodies is called nissl, nissl bodies or nissl substance. the terminal bouton is the end portion of an axon. it is also called an axon terminal or end bulb. the terminal bouton will be associated with another neuron in a synapse.