Fig. 3.

Lasing properties of 1-month mice. a, Examples of lasing spectra of a normal colon tissue from a 1-month old mouse (initial stage) stained with YOPRO (0.1 mM) under various pump energy densities. All curves are vertically shifted for clarity. b, Spectrally integrated laser output as a function of pump energy density extracted from the laser spectra of the normal colon tissue in a. The solid line is the linear fit above the lasing threshold, which was 11 μJ/mm². Tissue thickness = 10 μm. Cavity length = 15 μm. Excitation wavelength = 473 nm. c, Statistics of the lasing threshold for cells in the normal colon tissues stained with YOPRO from five 1-month old male mice (labeled as M1-M5) and five 1-month old female mice (labeled as F1-F5). Exemplary H&E images of male and female mouse colon tissues are provided in the insets. d, Histogram of all male/female normal colon cell lasing thresholds (N = 100) extracted from c.