Fig. 4: Type I collagen production in keratinocytes.

a–d The Col1a1 expression pattern in the dorsal skin was revealed by in situ hybridization. a’–d’ Immunofluorescence of pan-cytokeratin (KRT) and Hoechst signal (nucleus). e–h Procollagen expression from the 5 cm dermis to the 12 cm dermis. e’–h’ The heatmap shows the signal strength of the boxed region in (e–h). The expression patterns were confirmed in five independent samples at each time point, and the representative images are shown. Heatmap analysis was performed on three selected biologically independent samples from n = 5, and a representative example is presented. i–k Immunoelectron microscopy (IEM) using procollagen antibody. i’ Higher magnification views of the boxed region in (i). Arrowheads indicate the signals from the basement membrane (lamina lucida). j, j’ Positive control. Showing collagen production in mesenchymal cells. j’ The high magnification view of the boxed region in (j). The pink arrowheads indicate the IEM signals from in the mesenchymal cells. k, k’ Negative control (no antibody). k’ The high magnification view of the boxed region in (k). Yellow asterisks indicate the hemidesmosomes. The white dotted line indicates the basement membrane (lamina densa). The scale bars in a, a’, e are 50 μm, those in i, j, j’, k, k’ are 1 μm, and that in i’ is 500 nm. More than 20 IEM images were collected from the three biologically independent samples. And the representative images are shown.