Transdifferentiation of corneal epithelium into epidermis occurs by means of a multistep process triggered by dermal developmental signals

Differentiated cells of the corneal epithelium are converted to hair, along with their associated stem cells, then interfollicular epidermis, by means of a multistep process triggered by dermal developmental signals. The committed basal cells of the adult corneal epithelium dedifferentiate under the control of signals from an associated embryonic hair-forming dermis, likely Writs, and revert to a limbal basal cell phenotype. This initial process involves the down-regulation of Pax6 and the loss of expression of corneal-specific keratins and the induction of basal keratinocyte markers. These dedifferentiated cells are able to reinduce dermal condensations, which in turn induce the formation of hair follicles from cells that have lost Pax6 expression, by means of a Noggin-dependent mechanism. An epidermis is subsequently formed by cells derived from the newly segregated hair stem cells.