Abstract
The distribution, external surface morphology and ultrastructure of taste buds (TB) in the minnow, Pseudorasboraparva, were studied using scanning (SEM) and transmission (TEM) electron microscopy. SEM analysis revealed that TBs were widely dispersed on the skin of the head and lips as well as the mucosa within the oropharyngeal cavity, esophagus and branchial apparatus. The density of TBs was especially high on the lips, gill rakers, and palatal organ, reaching over 140 per mm2. Each TB showed two kinds of processes on the apical surface: thick rod shaped processes and microvilli.
TEM analysis showed the presence of three distinct cell types in each TB: tubular (t), filament-ous (f) and basal (b) cells. Their general morphology appears to be homologous to that of other species of fishes. The most striking find of this study, compared to previous studies of the mor-phology of fish TBs, is that a rod shaped process of t-cells contains tubules. Adirect opening ofthe tubules to the outer surface was sometimes observed at the base of the process. Typical synaptic contacts were seldom found, but somewhat thickened pazallel membranes with a few or no vesicular accumulation were sometimes found between nerves and either t-or b-cells.
