Distribution of cytokeratin filaments and vimentin in developing human taste buds

Taste buds in humans originate from approximately the 8th postovulatory wee k under the influence of ingrowing nerve fibers. Since they develop from lo cal epithelium, it is of interest whether or not prospective taste cells ma intain or develop characteristics of epithelial cells that are different fr om those of the adjacent epithelium during differentiation. The aim of this study was to monitor changes of the distribution of the cytokeratin filame nts (CKs) 8, 18, 19 and 20 ("gastrointestinal'' type), CK 7 ("ductal" type) , and CK 13 (maturation "mucosa type"), as well as vimentin in developing h uman taste buds and adjacent squamous epithelium. With the exception of CK1 3, which remains negative in taste bud anlagen and adult taste buds, all cy tokeratins tested were present in taste cells. With the progress of develop ment, the distribution of CKs becomes more and more restricted to taste cel ls and salivatory ducts as well as Ebner gland cells. Only CK20 is exclusiv ely specific to taste bud anlagen and sometimes to individual bipolar cells occurring in early stages (week 8-9). Vimentin was located mainly in mesod ermal derivatives but also in perigemmal epithelial cells during all stages of development. The occurrence of vimentin in "borderline" epithelia that interface with underlying connective tissue, i.e., in a region of discontin uity, may be associated with particular events in development, cell migrati on or even dedifferentiation.