Structure of bovine fungiform taste buds and their immunoreactivity for gustducin

The taste buds of bovine fungiform papillae were studied by light and electron microscopy using both histological and immunohistochemical methods. The taste buds existed in the epithelium of the apical region of the papillae. By electron microscopy, two types of taste cells, namely type I and type II cells, could be classified according to the presence of dense-cored vesicles, the cytoplasmic density and the cell shape. Type I cells were thin, had an electron-dense cytoplasm containing dense-cored vesicles, and possessed long thick apical processes in the taste pore. Type II cells were thick, had an electron-lucent cytoplasm containing many electron-lucent vesicles, rather than dense-cored vesicles, and possessed microvilli in the taste pore. Immunohistochemical staining with an antiserum against gustducin was investigated by both light and electron microscopy using the avidin-biotin complex (ABC) method. Some, but not all, of the type II cells exhibited gustducin immunoreactivity, whereas none of the type I cells showed any immunoreactivity.