LIGHT AND ELECTRON (SEM, TEM) MICROSCOPY OF TASTE-BUDS IN THE TENCH TINCA-TINCA (PISCES, CYPRINIDAE)

The ultrastructure and quantitative distribution of the taste buds (TB s) were studied in the oropharyngeal cavity and in skin from the head of the tench. All TBs are of similar structure, following an orthodox plan: the basal cells (1-2) are the basis of the bud, and vertically e longated gustatory cells and supporting cells span from the basal memb rane to the apex where they form a sensory zone (known as the gustator y pore). The basal cells have finger-like processes pointing towards t he nerve plexus. They do not show any hemidesmosomal connections with the basal membrane, Typical afferent synaptic contacts were found only at the basal cells and gustatory cells while no such contacts were fo und at the supporting cells. The highest concentration of TBs (up to 1 70 TBs mm-2) occurs in the epithelial lining of the distal part of the pharynx, the least (12 TBs mm-2) in the epidermis of the distal part of the head. The tops of most TBs protrude above the epithelium but th eir gustatory pores are slightly sunken, thereby protecting the apical processes of the gustatory cells from mechanical stimulation.