ULTRASTRUCTURAL OBSERVATIONS ON EXPERIMENTALLY PRODUCED MELANIN PIGMENTATION OF CORNEAL EPITHELIUM

  • 1 January 1976
    • journal article
    • research article
    • Vol. 85  (1) , 167-+
Abstract
Melanin pigmentation of the corneal epithelium was induced in pigmented guinea pigs by the topical application of colchicine to their eyes or by corneal cauterization with AgNO3. With colchicine the pigmentation was preceded by the development of an abnormal corneal epithelium in which numerous cells became arrested in cell division. The corneal melanosis resulted largely from the migration of melanocytes into the corneal epithelium from the normally pigmented contiguous conjunctiva and to a lesser extent from the presence of melanin granules within corneal epithelial cells. In both models a leukocytic and vascular invasion of the cornea preceded and accompanied the migration of melanocytes into the corneal epithelium. EM disclosed cells with the same morphology as conjunctival melanocytes between the epithelial cells of the cornea. Mature melanin granules were also present within some squamous epithelial cells as individual granules or as clusters. The ultrastructural findings are viewed in relation to how melanin granules are transferred from melanocytes to epithelial cells. Melanin granule transfer may follow the fusion of the membranes of the melanocytes and epithelial cells.