Figure 1. Inflated hydrogel mediates skin expansion.

a, Membranous signal (pink), from PFA-perfused Rosa26-mT/mG mice. Scale bar, 15 urn. b, Area of basal cells measured from a. c, Basal cell density. Number of nuclei per 1000 μm² (5 different independent areas of 40,000 μm² per mouse). d, Immunostaining for K14 (red), BrdU (green) and Hoechst for nuclei (blue) on whole mount epidermis. Scale bar, 20 μm. e, BrdU positive cells. f, Immunostaining for K14 (red), K1, K10 (green) and Hoechst for nuclei (blue) on tissue sections. Scale bar, 20 μm. g, Tissue thickness, 3 independent measurements per at least 2 sections per mouse. h, j, Adherens junctions (AJ) component a-catenin (h) and the a18 tension sensitive from of a-catenin (α18-cathenin) (j) colour-coded for signal intensity with ImageJ. Protein expression is visualized as a colour gradient going from black to yellow, with black as indicator of no expression and yellow as indicator of maximal expression. Scale bar, 10 μm i, k, Average integrated density signal for α-catenin (i) and α18-cathenin (k). Each data point is the average of 5 measurements per mouse. f, h, j, Dashed line indicate the basal lamina. b, c, e, g, i, k, In parentheses the number of cells and n=number of mice. Two-tailed Mann–Whitney test, mean per mouse + s.e.m.