CALCITONIN-GENE-RELATED PEPTIDE AND SUBSTANCE-P IMMUNOREACTIVITY IN THE MONKEY TRIGEMINAL GANGLION, AN ELECTRON-MICROSCOPIC STUDY

Calcitonin gene-related peptide (CGRP) and substance P (SP) immunoreac tivity was examined in neurons of the monkey trigeminal ganglion. More over, CGRP- and SP-positive varicose nerve fibers were found, occasion ally forming pericellular arborizations around trigeminal somata, whic h, at light microscopic level, suggested the existence of synaptic con tacts. Electron microscopic investigation however, revealed that altho ugh these varicose fibers ran in close range of somata and were contai ning accumulations of CGRP- and SP-positive vesicles, classical synapt ic contacts were not present.