Fig. 11. Diagram showing the relationship of the two layers of ciliary epithelium. Basement membrane (BM) covers their bases and their apices face each other across a potential space. The cells are united by several types of junctional complexes: 1, desmosomes; 2, gap junctions; and 4, puncta adherentes. Onlythe apices of the nonpigmented epithelial cells (NPE) are joined by “tight” junctions (3), composed of a zonula occludens usually combined with a zonular adherens complex. PE, pigmented epithelium.