BMP4-ß-gal perigemmal cells in fungiform and circumvallate papillae are not actively cycling. BMP4-ß-gal expression (X-gal reaction; blue) and Ki-67 immunostaining (dark brown) in circumvallate (A,B) and fungiform papillae (C,D) reveals that cycling cells surround taste buds basolaterally, but that BMP4-ß-gal positive epithelial cells do not reside in this mitotic domain. In circumvallate papillae (A,B) and fungiform papillae (C,D), white arrowheads indicate BMP4-X-gal positive cells in the epithelium that are not Ki-67 positive, although X-gal positive epithelial cells are located near perigemmal Ki-67 immunopositive cells (e.g. white arrow in B). Black arrows indicate BMP4 expressing cells in adjacent mesenchyme, in close proximity to taste buds and BMP4-Xgal positive perigemmal epithelial cells. In B and D, the black dotted line delineates the basement membrane separating the epithelium and mesenchyme. Scale bars: 20 μm.