Fig. 6.

Corneal epithelium-hair metaplasia. (A–E) After a few days of recombination of a corneal rabbit adult corneal epithelium with a mouse embryonic dorsal dermis (A), keratin 12 (K12) expression is down-regulated in the basal layer, whereas that of beta-catenin (βcat) is up-regulated (B). After 1 week, the beta-catenin-expressing cells form hair plugs (C). The hair that differentiates, originates from the rabbit cells, as shown by the label of mouse genomic DNA (D). After 2 weeks, islands of epidermal keratin 10 (K10)-expressing cells appear at the junction of hair follicles and what remains of corneal epithelium (E). After Pearton et al. 2005. Reproduced with permission of the Company of Biologists. (F–G′) The corneal phenotype of Dkk2^−/− mutant mice is opaque. An epidermis with a few hairs has formed (G,G′) instead of the transparent cornea (F,F′). After Mukhopadhyay et al. 2006. Reproduced with permission of the Company of Biologists. bl, basal layer; dc, dermal condensation; h, hair; hp, hair peg. Bars: A–E: 100 µm, F–G: 1 mm, F′,G′: 50 µm.