Fig. 7

Scales Organize Epidermal Sensory Innervation and Vascularization

(A–D) Lateral views of wild-type and eda^nkt/nkt mutant skin. Note the absence of scales in eda mutants. Boxes, areas of magnification for insets in (B) and (D). Axons and vasculature below the hypodermis are obscured by pigmentation, causing them to appear unconnected.

(E and F) Lateral views of wild-type and fgfr1a^spd/spd mutant skin and associated tracings (E″ and F‴). Arrows, scale orientation. Blue arrows, posterior-anterior oriented scales. Note in (E″) that nerves below scales (green) have a primarily dorsal-ventral orientation, whereas nerves above scales (magenta) have a primarily anterior-posterior orientation. Note reversed scale orientation (F) (blue arrows).

(G and H) Lateral and orthogonal views of skin from adults of the indicated genotypes. Orange and blue shading in (G) and (H) indicates squamated and naked skin, respectively. Arrowheads in (H′) indicate axons in the dermis (De); brackets and dashed lines indicate epidermis. (G.a), (G.b), (H.a), and (G.b) are single z planes through the skin.

(I) Boxplots of axon density based on quantification of Tg(p2rx3a>mCherry) expression in squamated and naked skin from animals of the indicated genotypes. Quantification includes all axons within the field of view (dermis and epidermis). ^∗p < 0.01, Wilcoxon rank-sum test. n = 28–71 regions of 0.038–0.077 mm² were analyzed per category.

Transgenes: keratinocytes (Tg(krt4:EGFP)), axons (Tg(p2rx3a>mCherry)) and endothelium (Tg(fli1a:EGFP)). Scale bars, 100 μm (A–F′, G, G′, and H–H″) and 25 μm (insets in B and D; F″, G.a, G.b, H.a, and H.b). See also Figure S7.