[Comparative morphological studies on surface ultrastructures of taste buds in the vertebrates].

The comparative ultrastructural studies of taste buds were made scanning electron microscopically in 15 different kinds of the vertebrtates, such as fish, frog, newt, lizard, snake, chicken, macaw, mouse, rat, guinea pig, rabbit, cat, monkey and human. There were no remarkable differences in the shapes and sizes of the taste pores on the surface ultrastructure of the taste buds among classes and species of such animals, but in the taste buds in frog, lizard and bird, there were some morphological characteristics in the distribution sites in the oropharynx. On the basis of the surface morphological features, these taste buds could be classified into five different types; type I named crater-like type, II buried type, III exposed type, IV disc type and V specific type. Most of the taste buds in these cases seemed to belong to type I or II groups. The relationships between the ultrastructural characteristics of taste buds and their physiological roles were discussed briefly from a viewpoint of evolution of taste sensation in the vertebrates.