Cell proliferation in the basal layer of circumvallate papillae was differently reduced by the two CYP dosing regimens.

(A). Ki67+ cells (magenta) in circumvallate papillae after saline injections (Saline, top row), a single injection of 75 mg/kg CYP (1CYP, middle row), or five injections of 15 mg/kg CYP (5CYP, bottom row) at 2 days (left column), 6 days (middle column), and 10 days (right column) post injection. Tissues were counter-reacted with Sytox green, a nuclear marker. For the 1CYP mice, Ki67+ cells were much reduced 2 days after injection. For the 5 CYP mice, Ki67 was suppressed at 2 and 6 days post injection. Scale bar = 20 μm. (B) Means ± SEM percent of Ki67+ cells relative to total cells plotted over days post injection. For 1CYP mice, Ki67 signal was significantly lower than saline controls at 2 and 4 days after CYP injection. For 5CYP mice, Ki67+ label was significantly lower than controls 2–8 days post injection and was significantly lower than 1CYP mice at 6 and 8 days post injection. All Ps < .05 or less: (1) * 5CYP < Saline, (2) # 1CYP < Saline, and (3) @ 5CYP < 1CYP.