Histochemical observation of distribution of chloride ion around ciliary epithelium

Chloride ions are shown to be actively transported by the ciliary epithelium. The distribution of these ions around the ciliary epithelium was studied by electron microscopy: chloride ions were deposited as silver chloride (AgCl) in the tissue. Albino rabbits, bullfrogs and chick embryos just before hatching were used. In all the animals examined, the concentration of chloride ions was lower in the nonpigmented and pigmented epithelial cells of the ciliary epithelium than in the extracellular space. The chloride ions appeared to accumulate between the nonpigmented epithelial cells.