Fine Structural Localization of Nucleoside Phosphatase Activity in the Ciliary Epithelium of Albino Rabbits

¹ Yale University School of Medicine, Section of Ophthalmology New Haven, Conn.

Nucleoside phosphatase activity was demonstrated in the ciliary epithelium of albino rabbits using glutaraldehyde fixed and fresh tissues. The reaction product resulting from hydrolysis of adenosine triphosphate (ATP) was primarily found on the interdigitated cell membranes of nonpigmented epithelium and on the boundary between this cell layer and the pigmented epithelium. The reaction product seemed to occur equally on the cell membranes at the apical and the lateral interdigitations, but the free surface of the nonpigmented epithelium facing the posterior chamber showed no obvious reaction product. In contrast to the interdigitated membranes of the nonpigmented epithelium, little activity was noted on the cell membranes at the lateral and basal margins of the pigmented epithelium. The reaction productcould be demonstrated on the cristae of swollen or broken, but not intact, mitochondria in fresh tissue incubation. The fine structural localization of nucleoside phosphatase activity is discussed with reference to possible sites of active transport