Fig. 5: Epidermal BMP signalling is required for rete ridge formation.
From: Rete ridges form via evolutionarily distinct mechanisms in mammalian skin
a, Fingerpad rete ridges form postnatally after the cessation of sweat gland formation in mice. Representative immunostains of fingerpads from P0, P5, P12 and P21 mice stained for ITGA6 and SOX9 (n = 3 for each time point) are shown. b, BMP signalling is active in the fingerpad. Representative immunostains of P5 (n = 3) and P21 (n = 3) fingerpads stained for SMAD1 and phosphorylated SMAD1/5 (pSMAD1/5) are shown. c, Epidermal BMP signalling is required for rete ridge formation in mouse fingerpads. Schematic of K14-Noggin mouse (left), representative H&E stains of WT and K14-Noggin fingerpads (centre) and quantification of fingerpad rete ridges per millimetre (right). P = 7.78 × 10−6 from t-test. D and V indicate dorsal and ventral orientation of the digit section. Zoom-outs of these representative images are in Extended Data Fig. 5h. d, Inhibition of epidermal BMP signalling via postnatal Bmpr1a KO inhibits rete ridge formation in mouse fingerpads. Schematic of K14-CreERT;Bmpr1afl/fl mouse (left), representative H&E stains of tamoxifen-treated K14-CreERT (Ctrl, n = 3) and K14-CreERT;Bmpr1afl/fl (TAMX, n = 4) fingerpads (centre) and quantification of fingerpad rete ridges per millimetre (right). P = 0.01039 from t-test. Zoom-outs of these representative images are in Extended Data Fig. 5i. e, Proposed models of rete ridge formation in skin represented temporally in two dimensions (top) and morphologically in 2.5 dimensions (bottom). Scale bars, 100 μm. *P < 0.05, ***P < 0.001. Illustrations in a–e were created using BioRender. Thompson, S. (2026) https://BioRender.com/8rd8cz9.
