OCCURRENCE OF SUBTYPES OF GUSTATORY CELLS IN CAT CIRCUMVALLATE TASTE-BUDS

Transmission-electron microscopy of cat taste buds confirmed that, as in other mammals, each taste bud comprised four distinct types of cell s: Type I, Type II, Type III (gustatory), and Type IV (basal) cells. G ustatory cells made synaptic contacts with nerves to which synaptic ve sicles were gathered, The following are the main findings on the cat g ustatory cells: 1) The synaptic vesicles of gustatory cells were essen tially all dense-cored in type; small clear vesicles, which usually ar e intermingled in other mammals, could not be found, 2) The vesicles w ere accumulated not only in the synaptic area but also in the basal cy toplasm, This implies endocrine and paracrine functions, 3) On the bas is of the fine structure of the vesicles, two subtypes of gustatory ce lls were discriminated. A large part of the cells contained vesicles m easuring about 180 nm in diameter, while a small part had smaller ones of about 100 nm in diameter. This is the first demonstration of a dua l population of gustatory cells in mammals, suggesting different messe nger substances utilized.