Fig. 1: BrdU-positive label-retaining cells are maintained in CVP taste buds during homeostasis and regeneration.

a Schematic of the experimental design for the identification of label-retaining cells. b, c At 12 h after the last injection (no chase), the proliferative basal cells are incorporated with BrdU label (green). b', c' HE staining reveals the basal cells labeled with BrdU in the CVP epithelium. d, e BrdU-positive label-retaining cells (green) are observed within the taste buds after 2 weeks of the chase period. The label-retaining cells are colocalized with Type II and Type III taste receptor cells that are marked by gustducin and Snap25, respectively. d'–e' H&E staining of the taste buds of the CVP after 2 weeks of BrdU treatment. Arrowheads indicate BrdU-positive label-retaining cells expressing Type II or Type III taste receptor cell markers. f BrdU-positive label-retaining cells with pan-taste receptor marker K8 are observed in the taste buds after 6 weeks of the chase period. g, h The label-retaining cells are colocalized with Type II and Type III taste receptor cells. f'–h' H&E staining reveals taste buds of the CVP after 6 weeks of BrdU treatment. Arrowheads indicate BrdU-positive label-retaining taste receptor cells. i Quantification of BrdU-positive cells was performed in the CVP at 2 and 6 weeks after BrdU injection. Label-retaining cells were gradually reduced after BrdU injection, and a small number of cells were maintained at 6 weeks. j The schematic indicates the experimental procedure for the identification of label-retaining cells after GLx. Nerve transection was performed at 4 weeks after BrdU injection, and mice were sacrificed at 2 and 6 weeks after GLx. k A small number of BrdU-positive label-retaining cells are observed in the taste buds at 6 weeks after GLx. l, m The label-retaining cells are colocalized with Type II (gustducin) and Type III (Snap25) taste receptor cell markers. k'–m' H&E staining indicates the regenerated taste bud structure of the CVP at 6 weeks after GLx. The arrowhead indicates BrdU-positive taste receptor-retaining cells. n The number of BrdU-positive label-retaining cells in the circumvallate papilla was not significant among the groups at 2 and 6 weeks after GLx. n = 10 per condition. Data on the graph are displayed as the mean ± SD. Scale bar: 25 µm.