BMP4-ß-gal is expressed in both circumvallate and fungiform papillae of adult mice. A. In the circumvallate papilla, X-gal positive cells are evident in variable numbers within taste buds (intragemmal cells - one example outlined with white dashed line, and in papillary epithelium adjacent to taste buds (perigemmal cells, white asterisks), as well as in the subepithelial mesenchyme (white arrow). B. The heterogeneous nature of BMP4lacZ expression is evident at higher magnification. Some intragemmal fusiform cells express moderate levels of ß-galactosidase (green arrowhead), while others have higher levels (white arrowhead). Some basal epithelial cells are also strongly X-gal positive (black arrowhead), as are subepithelial lamina propria cells (white arrow). C. In fungiform papillae, BMP4-ß-gal is expressed in epithelial cells around fungiform taste buds (black arrowhead) and filiform papillae (black arrows), and is also evident in lamina propria beneath fungiform taste buds (white arrow). D. X-gal positive epithelial cells are common perigemmally in the epithelium (black arrowhead), as are positive mesenchymal cells (white arrows). E. A schematic diagram of circumvallate papillae is divided into six regions for each trench: lateral top, lateral middle, lateral bottom, medial bottom, medial middle, and medial top for each of the paired circumvallate trenches. The number of BMP4-ß-gal intragemmal cells per taste bud profile in the bottom of the papilla is significantly greater than in the middle part, and the middle part has significantly more BMP4-ß-gal cells than the top region (p < 0.01, Tukey comparison test); data indicate mean +/- standard error; n = 6 mice; at lease 50 taste buds were counted for each location. Scale bars: 20 μm.