Normal ultrastructural organization of the epidermis and dermal-epidermal junction in mTurq2-Col4a1/+ embryonic skin. Transmission electron micrographs of ultrathin skin sections from E18.5 WT control (A, C, E, and G) and mTurq2-Col4a1/+ (B, D, F, and H) embryos. (A and B) Ultrastructural overview of skin architecture. Der = dermis, BL = basal layer, SL = spinous layer, GL = granular layer, SC = stratum corneum, HF = hair follicle. The dotted line denotes dermal–epidermal boundary. Scale bars, 10 µm. (C and D) Zoomed in view of the boundary between the basal epithelial layer and dermis. Dermal–epidermal junction (DEJ) is highlighted in pink. Dotted boxes denote regions magnified in E and F. Scale bars, 2 µm. (E and F) Two representative examples of DEJ region of the skin from WT (E and E’) and mTurq2-Col4a1/+ (F and F’) embryos. Nuc = nucleus. Scale bars, 500 nm. (G and H) Zoomed in views of individual hemidesmosomes at the DEJ. HD = hemidesmosome, PM = plasma membrane, LL = lamina lucida, LD = lamina densa. Scale bars, 100 nm.