Shh signaling and regulatory gene expression in mouse taste buds.

In mammals, taste buds arise from local epithelium and are maintained by continuous cell renewal (Beidler and Smallman, 1965; Farbman, 1980; Delay et al., 1986; Stone et al., 1995). The life span of taste cells is estimated to be ~10 days. Denervation causes the degeneration of taste buds, indicating that the taste nerves trophically maintain the taste buds. It is assumed that cell proliferation, differentiation and death for taste buds are regulated in a coordinated fashion. However, the mechanism of each process in taste buds remains to be clarified.