Corneal epithelium is traditionally thought to be a self-sufficient, self-renewing tissue
implying that its stem cells are located in its basal cell layer. Recent studies indicate
however that corneal epithelial stem cells reside in the basal layer of peripheral cornea in
the limbal zone, and that corneal and conjunctival epithelia represent distinct cell lineages.
These ideas are supported by the unique limbal/corneal expression pattern of the K3 keratin
marker for corneal-type differentiation; the restriction of the slow-cycling (label-retaining) …