BrdU incorporation in taste epithelium of 5-6 week-old wild-type and p27 -nullizygous mice. (A) Anti-BrdU immunolabeling of frozen sections 1, 3, 7 and 15 days following intraperitoneal injection of the BrdU. Labeled nuclei in wild-type (+/+) and mutant (-/-) CV papillae are evident as red ovoids. In large panels, dashed lines indicate taste bud boundaries; dotted lines demarcate the papilla surface. Maximum projection images from z-series of 10 optical sections, 1 μm steps. (a) - (h) Confocal overlay images of fluorescence double-labeling for BrdU and either p27 (in a, c, e and g) or TROMA-1 (in b, d, f, and h) (green), showing the taste buds corresponding to the dashed outlines in the wild type (+/+ panels, above) or the mutant (-/- panels, below), respectively. (B) Plot of mean number (± SEM) of BrdU-positive nuclei per bud for 3 replicates at each time point. (ANOVA: F = 9.69, p < 0.001). * indicates p < 0.02 and ** indicates p = 0.001 in post-hoc comparisons to wild-type. Scale bar: 10 μm.