Comparison of volume and cell number in FG taste buds from 5-6 week-old wild-type and p27 -nullizygous mice. (A) Confocal fluorescence images of single optical sections through a taste bud from a p27+/+ (+/+) and a p27-/- (-/-) anterior tongue whole-mount illustrating co-labeling with antibody to cytokeratin 8 (TROMA-I; green) and the nuclear stain TO-PRO-3 (red). The cytokeratin 8-defined perimeter was used for calculations of bud profile area, and taste bud volume was estimated by summing areas in all optical sections through a single bud. Cell nuclei lying within the bud perimeter were counted to estimate taste cell number. (B) Plot of taste cell number versus taste bud volume in papillae from both genotypes. Regression analysis indicates that the relationship between these parameters is nearly identical for the two groups (wild-type r = 0.98, mutant r = 0.97). Scale bar: 10 μm.