Extended Data Fig. 2: Full-thickness Histological “Zoo” From Aquatic and Terrestrial Mammals.
From: Rete ridges form via evolutionarily distinct mechanisms in mammalian skin
(a) Graphical summary representing anatomical sites skin samples were collected from across species to generate the histological “zoo”. See Methods for complete details on pig breed backgrounds. (b) Representative H&E and Herovici stains from trunk skin of long-beaked common dolphins (n = 3), bottlenose dolphins, short-beaked common dolphins (n = 3), Yucatan miniature “hairless” pig, humans, Mangalitsa pigs, North American grizzly bears, rhesus macaques, naked mole rats, common marmosets, and mice. Same number of biological replicates as Fig. 2a. Dashed rectangles represent regions of zoom-in in Fig. 2a. (c) Representative surface images of long-beaked and short-beaked common dolphin trunk skin. (d) Representative image from Yucatan miniature “hairless” pig skin sample to illustrate hair density that is too low to reliably quantify. (e) Representative H&E stain of skin from an adult Hanford mini-pig (n = 1). Dashed box indicates region of zoomed inlay (top). Zoom-out imaged on 10x objective, zoom-in imaged on 20x objective. (f) Quantification of histology for epidermal thickness (left, inter-ridge only, if applicable) and the correlation between epidermal thickness (right, inter-ridge only, if applicable) and hair density. Number of replicates same as main Fig. 2c-d. Shared letters indicate no difference (p-value > 0.05) and different letters indicate significant difference (p-value < 0.05) from one-way ANOVA plus Tukey’s HSD (exact p-values in Source Data). Correlation statistic shown is adjusted coefficient of determination, p-value = 5.532e-10. (g) Representative immunostains from fetal gestational week 17 (GW17) marmoset and neonatal naked mole rat for ITGA6/LEF1 and KRT15/LEF1, respectively (n = 3). HF=hair follicle. (h) Breeding strategy to generate K14-Cre;Lef1fl/fl (Lef1-eKO) mice from crossing K14-Cre;Lef1fl/+ (Lef1-Het) mice with Lef1fl/fl (WT) mice. (i) Representative immunostains (n = 3 each) from embryonic day 16.5 (E16.5), postnatal day 5 (P5), and P21 WT (top) and Lef1-eKO (bottom) mice for Itga6/Lef1. Arrows indicate hair follicles. Scale bars in (b) represent 250 um; in (c-d) 1 mm; in (e) zoom-out 250 um and zoom-in 100 um; in (g, i) 100 um. Cetacean illustrations in a–c and f were obtained from the NOAA Fisheries Species Directory entries for bottlenose dolphin, long-beaked common dolphin and short-beaked common dolphin. Illustrations in a–i were created using BioRender. Thompson, S. (2026) https://BioRender.com/8rd8cz9.
