Outgrowth of cells from human conjunctival explants onto cornea in vitro.

The epithelium was removed from human corneas, and samples of conjunctival tissue were cultured as explants on the denuded corneal surface for 1 and 2 weeks. Cells migrating from the conjunctival explants onto the corneal surface produced a multilayer where cells on the surface generally showed a flattened appearance. The apical membrane of these cells demonstrated villi as well as microplicae. Surface projections were also detected on cells in the deeper layers of the epithelium. Neighbouring cells were connected by junctional complexes. After 2 weeks, however, a lack of intercellular junctions in some areas resulted in the formation of intraepithelial cystoid spaces. Basal cells were connected to the underlying basement membrane by hemidesmosomes. Although transdifferentiation of the cells into a corneal epithelium was not observed within the 2 weeks, the present system provides a tool for studies on factors affecting reepithelialization of corneal epithelial defects by conjunctival cells.