Fig. 3 . Diagram of possible secretory pathways in the ciliary processes. AA, ascorbic acid; CA, carbonic anhydrases. (Adapted from Wiederholt M, Helbig, H, Korbmacher C: Ion transport across the ciliary epithelium: Lessons from cultured cells and proposed role of the carbonic anhydrase. In Botné F, Gross G (eds): Carbonic Anhydrase, p 232. Basel: Verlag-Chemie, 1991)