New details of the ultrastructure (TEM, SEM) of taste buds in fishes.

Quantitative distribution of the taste buds (TB) in different parts of the body and the fine structure of the TB components are described in Cobitis taenia L. No evidence of synaptic contacts between any cellular components in the TB has been found. The afferent synapses have been recognized only at the gustatory cells and at the basal cell. The microvillar processes on the upper side of the basal cell are demonstrated for the first time in fishes. These processes resemble those at the basal cells in the TB of tetrapods and at the Merkel cells, scattered in the epidermis of all vertebrates. Since the basal cells of fish TB correspond also to other criteria of the Merkel cells, its mechanoreceptive function in the TB is discussed. A relatively large number of atypical gustatory cells has been found in the studied material. As the examined specimens of C. taenia lived for a long time in aquarium conditions, it may be supposed that these gustatory cells are damaged by pollutants introduced mainly with food such as Tubifex. For purposes of comparison, a related species, Misgurnus fossilis L., was used in the study.