Fig. 2. In situ hybridization reveals that β-catenin responsive cells are primarily basal cells and often express Sonic Hedgehog (Shh).

Representative 0.75 µm optical sections of taste buds (encircled by white dash) in the circumvallate papilla reveal both Shh (green), and LacZ expressing (red) cells within taste buds; co-labeled cells are yellow. a) At 10 weeks of age, numerous double labeled cells are evident in taste buds of young mice (white arrowheads), as are cells singly labeled for Shh (open arrowhead: Shh-only expressing type IV cell), and cells labeled only for LacZ (white arrow: LacZ-expressing fusiform cell). b) In addition to Shh/LacZ double labeled cells within taste buds (white arrowhead), occasional basal cells outside of taste buds express LacZ (yellow arrow); Blue arrow: LacZ expressing intragemmal basal cell. c) At 25 weeks, LacZ expression is greatly diminished in circumvallate taste buds; we detected only sparse and very week expression of the reporter transcript (dim red; blue arrow), and sparsely encountered cells also double labeled for Shh. d) Shh expression (green; white arrowhead) in taste buds of 25 week-old mice, by contrast, was comparable to that detected in taste buds from mice at 10 weeks of age. Scale bars = 20 µm in all panels.