Figure 1.

Fundamental structure of the adult newt skin. Images were obtained from transverse sections of the dorsal skin of the forearm unless otherwise mentioned. (a) A representative image of the skin. Masson’s trichrome stain. Blue/gray area: collagen-rich connective tissue. (b) A representative image of the epidermis. Hematoxylin-eosin stain. Cells in both the basal layer and the transitional layer contained melanin pigments. (c–f) Sample images showing cell division along the basal layer. DAPI stain of nuclei or chromosomes. White arrowheads: spindle pole. The basal stem cells divided either horizontally (c) or vertically (e). (g,h) Representative images of the dendritic melanophore. DAPI stain of nuclei is shown in (h). The cell had a cell body (arrows) located at the innermost region of the transitional layer, and extended dendritic fibers along the border between the transitional layer and the basal layer. (i) A representative image of lateral skin with a black and orange color pattern. V: ventral side. (j) A representative image of the plane orange area of ventral skin. The top is the ventral side. Note that the epidermis was transparent in lateral and ventral skin with a color pattern. We could not detect dendritic melanophores or pigment granules in cells of the basal and transitional layers. BL: basal layer; D: dermis; Ep: epidermis; GG: granular gland; M: muscle; MG: mucous gland; Mp: melanophore; PLC: pigment cell layer; SC: stratum corneum; TL: transitional layer; Xp: xanthophore. Asterisks: blood capillaries. Scale bars: 100 μm (a,i); 40 μm (b,g,h,j); 50 μm (c,e); 10 μm (d,f).