Fig. 1.
Mechanism for aqueous secretion. An active movement of Na+ and HCO3− increases the solute concentrations in the posterior chamber in proximity of the ciliary processes and creates a positive osmotic gradient that recalls fluids collected in the ciliary tissues because of diffusion and ultrafiltration. ATPase, adenosine triphosphatase; NPE, nonpigmented epithelium; PE, pigmented epithelium.