BMP4-ß-gal is expressed in perigemmal cells of both circumvallate and fungiform papillae. A, B. X-gal positive cells in the circumvallate papilla comprise both extragemmal (A; white arrowheads) and perigemmal (A and B; white asterisks) K14-immunopositive cells. Some perigemmal BMP4-postivie cells are not K14-IR (B, white arrow). C, D. In fungiform papillae, perigemmal BMP4-LacZ expressing epithelial cells are K14-immunonegative (C, D; white arrows), or K14-IR (C, white asterisk). Black arrows indicate X-gal positive mesenchymal cells in close apposition to X-gal positive perigemmal epithelial cells. Scale bars: 20 μm.