Absorption of horse-radish peroxidase by the conjunctival epithelium of monkeys and rabbits.

Horse-radish peroxidase was instilled into the conjunctival sac of rabbits and Cynomolgus monkeys. After an interval of 5, 30 or 60 min the conjunctival epithelium was studied by electron microscopy. The tracer was found to be absorbed predominantly by type-V cells, which are rich in mitochondria; this process was found to occur more rapidly in the rabbit than in the monkey. The particles were primarily incorporated into pinocytotic vesicles and phagosomes and were then either digested by phagolysosomes or transported through the basal portion of the surface epithelial cells into the expanding intercellular spaces distal to the junctional complexes.