Fig. 13. Electron micrograph of the ciliary epithelium of the albino rabbit after staining for carbonic anhydrase. The reaction product is seen predominantly at the membrane infoldings (in) of the nonpigmented epithelium (NPE) and pigmented epithelium (PE), as well as on the apical cell membranes (Ap). Cytoplasmic staining is found only in the PE. (Lütjen-Drecoll E, Loennerholm G: Carbonic anhydrase distribution in the rabbit eye by light and electron microscopy. Invest Ophthalmol Vis Sci 21:782, 1981. Copyright held by The Association for Research in Vision and Ophthalmology.)