Fig. 2: Development of dermal collagen structure during growth.
From: Keratinocyte-driven dermal collagen formation in the axolotl skin
a–d Histological observation of the axolotl dorsal skin. Masson’s trichrome staining was performed for 5 to 12 cm dermis. Blue indicates collagen, red indicates cytoplasm, and dark brown color indicates nuclei. e–t Immunofluorescence of e–h COL1a (green), i–l COL3 (red), and nucleus (Hoechst 33342; blue) in the axolotl dermis. m–p Merge images of (e–l). q–t High magnification view of the boxed region in (m–p). SB, SS, and SC indicate stratum baladachinum, stratum spongiosum, and Stratum compactum. The open windows in q‒t display views with one color deleted. For example, ΔCOL1a indicates that the green signal of COL1a is omitted from the region. The expression patterns were confirmed in five independent samples at each time point, and the representative images are shown. u Analysis of thickness of collagen layer (n = 4 biologically independent samples) Each point on the box plot represents all measured data points. p values from up to down: 1.40 e−37, 3.10 e−42, 2.91 e−32, 2.60 e−9, 4.92 e−34, 2.72 e−30. v Counting the number of nuclei in the dermis (n = 4 for 5 cm, and n = 5 for 8, 10, and 12 cm biologically independent samples) Each point on the box plot represents all measured data points. p values from up to down: 1.63 e−10, 3.74 e−9, 3.11 e−8, 1.16, 6.28 e−7, 0.025. w Immunofluorescence of COL1a (green), COL4 (red), and nucleus (Hoechst 33342; blue) of the stratum coniunctum. w’ High magnification view in w. x Immunofluorescence of COL1a (green), COL4 (red) and nucleus (Hoechst 33342; blue) of the 12 cm. x’ High magnification view in x. The scale bars in (a, e, q) are 50 μm, and that in w is 10 μm. a–d, e–o, q–t, and w–x are the same magnification. The expression patterns were confirmed in five independent samples at each time point, and the representative images are shown. The white dotted line in q–t indicates the dermal collagen layer. The statistical analysis was performed using two-tailed ANOVA, followed by pairwise two-tailed t-tests with Bonferroni correction. *p < 0.05, **p < 0.025, ***p < 0.01. n.s. no significant difference. Each box represents the interquartile range (IQR, the range between the 25th and 75th percentile) with the mid-point of the data, bars indicate the upper and lower value within 1.5 times the IQR. Source data are provided as a Source Data file.
