Phagocytosis of latex microspheres by the epithelial cells of the guinea pig conjunctiva.

The capability of conjunctival epithelial cells to phagocytize particulate foreign matter was studied experimentally in the guinea pig. Perilimbal conjunctival epithelium was prepared for transmission electron microscopy by perfusion fixation 4 and 24 h after instillation of latex microspheres (0.79 mu in diameter) into the lower conjunctival fornix. A varying number of microspheres were internalized by the superficial epithelial cells in both cases. The intracellular microspheres, single (at 4 and 24 h) or aggregated (only at 24 h), were always membrane-enclosed, corresponding to primary phagosomes. Some indications of secondary phagosomes were seen as well. In the 24 h specimens, microspheres were present also in the intermediate epithelial cells, implying a transfer from superficial to deeper cells. Thus, superficial as well as intermediate epithelial cells of the guinea pig conjunctiva are capable of active phagocytosis of inert particles.