Functional Cell Types in Taste Buds Have Distinct Longevities
Figure 2
EdU-labeled nuclei in non-taste lingual epithelium surrounding taste buds turn over rapidly. A,
wide-field fluorescence micrograph of circumvallate papilla, 1 day after a single pulse of EdU. Many EdU-labeled nuclei (red) are visible along the base of the epithelium. Taste buds are immunostained (grey) for KCNQ1, a marker for all taste cells. The location of EdU+ nuclei, whether inside or outside of taste buds cannot be judged from a wide-field micrograph such as this. B–D, Higher power single plane confocal micrographs of circumvallate taste buds, 1, 3, or 5 days after injecting EdU. The large majority of EdU-labeled epithelial cells are outside of taste buds. Basal and apical limits of the epithelium are indicated with white solid and dotted lines respectively to highlight the rapid migration of newly-born non-taste cells from the stratum basale to the superficial epithelial strata. E, Cartoon depicting progression of EdU-labeled non-taste nuclei vertically through the epithelium and their simulataneous change of shape from ovoid at the base to horizontally flattened at the apical surface. F, Plot of EdU labeled non-taste nuclei per unit area versus days post-injection. Data were obtained from micrographs of circumvallate trench such as those in B–D. Each symbol represents data from a separate mouse. The solid line is a best-fit 1-phase exponential decay curve that yields a half-life of 2 days (R2 = 0.98) for non-taste epithelial cells surrounding taste buds. The dashed line is a smoothed line through the average values at each time point in the time course. Scale bars, 20 µm.