Electron histochemical study of alkaline phosphatase activity in the pecten oculi of the chick

Alkaline phosphatase activity in the pecten of chicks was studied electron histochemically. Alkaline phosphatase activity was located in the plasma membrane of the cytoplasmic processes in the luminal and basal portions of the endothelial cells of the capillary, in the plasma membrane of cells with pigmented granules and in the plasma membrane of cells in the vitreous in contrast with the basement lamina of the cells with pigmented granules. The cytoplasmic processes of the luminal and basal portions of the capillary endothelium and the plasma membrane of the cells with pigmented granules may play a role in the exchange of metabolites between the pecten and the vitreous. In the pecten of dark adapted eye, alkaline phosphatase activity could not be demonstrated histochemically. Thus, darkness may make the exchange of metabolites between the pecten and the vitreous less active.