(A) Representative transverse section of distal colon from Lgr5-lacZ mice stained for lacZ. Scale bar = 10 μm. (B) Timing of loss of Lgr5⁺ stem cell lacZ signal after 1% DSS treatment. Left panel — H&E and lacZ staining of distal colons from Lgr5-lacZ mice at day 0, 2, and 7 after 1% DSS treatment, quantified in the right panel. Scale bar = 50 μm. For Lgr5 recovery, Lgr5-lacZ mice were treated with 1% DSS for 2 days followed by 2 days normal drinking water. Data (mean ± SEM) are from 6 mice/time point, evaluating 5 circumferences/mouse, except for Lgr5-lacZ recovery data, which are from 11 circumferences from 3 mice. ***P < 0.001 vs. day 0. Note, P < 0.001, 2-day recovery vs. day 2 DSS. (C) CESCs remain physically present at the crypt base after 2 days of 1% DSS treatment. White arrows identify CESCs between red fluorescent cKit⁺ cells in colonic crypts. Data (mean ± SD) are collated from 100 crypts (4 mice/time point), P > 0.05, 2-tailed Student’s t test. Scale bar = 10 μm. (D) Number of proliferating CESCs dramatically decreases at day 2 of 1% DSS treatment. S-phase cells were pulse-labeled with EdU for 2 hours before sacrifice. Scale bar = 50 μm. Data (mean ± SD) show representative results from 3 independent experiments. (E) Lineage tracing using Lgr5-mTmG transgenic mice demonstrates GFP⁺ CESCs at the crypt base after 2 days of 1% DSS treatment. Data (mean ± SD) are collated from 137 and 179 intact crypts for control and DSS groups, respectively, from 3 mice/group. P value, 2-tailed Student’s t test. Scale bar = 10 μm. The box plots depict the minimum and maximum values (whiskers), the upper and lower quartiles, and the median. The length of the box represents the interquartile range. 4-OHT, 4-hydroxytamoxifen.