DEVELOPMENTAL-CHANGES IN THE STRUCTURE OF MUCOUS-MEMBRANE IN THE ORAL CAVITY AND TASTE ORGANS IN TADPOLES OF THE FROG, RANA-TEMPORARIA (SEM)

The lining of oral cavity and its changes during development (from the 22nd larval stage to the metamorphosis) were investigated by scanning electron microscopy (SEM). Several types of premetamorphic papillae (finger-like, cone-like, palm-like and bush-like), as well as a fold in the anterior palatine region could be distinguished by SEM. Most of the papillae begin to form at stage 22, complete their development by stage 27 and start to degenerate at stage 41. The apical parts of all papillae and their remifications show the presence of taste buds. Thus, apart from performing a mechanical functions, the papillae also act as sensory organs. Two successive generations of taste organs occur during tadpole development: taste buds followed by taste discs. This study also presents the development of the lingual fold and changes of its dorsal surface.