Ultrastructural and histochemical changes in the frog taste organ following denervation.

The fine structure of the taste organ in the Rana catesbeiana was observed by light and electron microscopy. The taste organ consists of three distinct cell types, the taste, supporting and basal cells as well as nerve elements. The present findings suggest that the taste cell might function not only as a chemoreceptor cell, but also as a paracrine cell. The basal cell also may have a dual function as both mechanoreceptor and paracrine cell. Furthermore, taste organs have been examined at intervals from 3 hrs to 120 days after sectioning of the glossopharyngeal nerves. The taste organs were almost intact throughout the experimental period after denervation and even after ceasing to produce impulses from chemical or mechanical stimuli. The dense-cored vesicles of the taste or basal cells, which may possess a paracrine action, still remain in the taste organ even 120 days after denervation. It can be concluded that the morphological integrity of the frog taste organ does not absolutely need the presence of the gustatory fibers in contrast to the nerve-dependent nature of the mammalian taste bud.