Migration of Limbal Melanocytes

Abstract

RECENTLY, we suggested^1,2 that pigmented melanocytes from the limbus of the eye of the guinea-pig could be stimulated to enter the basal layer of corneal epithelium. Within the cornea, normally transparent and colourless, the pigmented dendritic cells could be studied in vivo and in vitro with little technical difficulty. Our method involved topical application of a solution of colchicine (0.1–0.01 per cent in saline) to the cornea once or twice daily for a week or more. In another experiment a solution of alloxan was injected into the anterior chamber of the eye. In both cases melanocyte migration occurred after the superficial cornea became vascularized; the greater the extent of superficial corneal vascularization, the more extensive the melanocyte invasion of the basal layer of the corneal epithelium. As corneal pigmentation increased, the limbal band became less pigmented. The observations seemed to support the concept that mature melanocytes (at least the melanocytes from the corneal limbus of a mature animal) are capable of migration, and that there is a relationship between this movement and the underlying neovascularization. It should be made clear that the melanocytes in the experimental model were not in direct contact with the new vessels, but were separated from them by Bowman's membrane and a variable amount of corneal stroma.