Immunohistochemical localization of pleiotrophin and midkine in the lingual epithelium of the adult rat

Distribution of two heparin-binding molecules, pleiotrophin (PTN) and midki ne (MK), was investigated by immunohistochemistry in the lingual epithelium of the adult rat. In the lingual epithelium, both PTN- and MK-like immunor eactivities were observed in its basal cell layers, showing a mesh-like app earance. These molecules were also found along the surface of the taste bud cells; an intense immunoreaction was detected at the base of the taste bud s in the circumvallate and foliate papillae. At the electron microscope lev el, the immunoreactive products were localized on the cell surface and base ment membrane at the base of the taste buds. The immunoreactivity for PTN w as distributed more diffusely than that for MK. It was suggested that these molecules may be involved in the differentiation and maintenance of taste bud cells, possibly via their: trophic effect upon approaching nerves.