Regeneration of Epidermal and Dental Tissues, Lens, and Cornea

All vertebrates regenerated epidermis, periodontal tissues, and corneal epithelium, but only a few species could regenerate teeth and lens. Epidermis, hair, nails, periodontium, and cornea continually turned over and maintained their structure through maintenance regeneration and response to injury. Mammalian skin epidermis, a multilayered epithelium with appendages like hair follicles, sebaceous glands, and sweat glands, recovered from wounds via basal cell migration. Nails, hardened epidermal variants of hair, regenerated from a matrix of transient amplifying cells. Teeth, similar to nails, were hair follicle variants developed through epithelial–mesenchymal interactions, with regeneration possible in some species like adult urodele amphibians and crocodilians. Lens regeneration was extensively studied in adult newts. Corneal epithelium regenerated continuously or after injury by adult stem cells in the limbus.