Cytochrome oxidase staining facilitates unequivocal visualization of the primary gustatory area in the fronto-operculo-insular cortex of macaque monkeys

Fronto-opercular and insular cortices of Japanese macaques were histochemically stained for cytochrome oxidase activity. The laminated pattern of enzyme activity differed in the different cytoarchitectonic areas. Area G, the presumed primary gustatory area, as well as area 3 were prominent because the third stripe, corresponding to the termination layers of the specific thalamocortical projection in these areas was very dark and thick in comparison with that from the neighboring areas. This approach provides a convenient histological aid for identification of area G.