Uptake and Intracellular Digestion of Protein (Peroxidase) in Planarians

Abstract

It is thought (Willier ct a/., 1925;Jennings, 1957;Rosenbaum and Rolon, 1960a) that digestion in aquatic planaria is exclusively intracellular, occurring in the spherules of the phagocytic gastrodermal cells. There is, however, very little information concerning the formation of the spherules, the rate of digestion of their contents, and their ultimate fate. Data based on the rate of disappearance of alkaline phosphatase from the spherules in planarians which had been fed raw earthworms (Osborne, 1955) were inconclusive, because of the impossibility of distinguishing exogenous from endogenous enzyme. Nor was it possible in these studies to determine whether the uptake of nutrients occurs exclusively by the phagocytic action of the gastrodermal cells. A new approach to these problems was suggested by the experiments of Straus (1959) on the intracellular disposition of parenterally administered horseradish peroxidase in the rat. Peroxidase, which does not occur in most cells of animal organisms, is readily visualized histochemically and can be used as a tracer for exogenous protein.

Chemistry of Learning

“…Osborne and Miller (1962) reported a definite penetration of peroxidase enzyme through the intact epidermis, which seemed to be taking place via the canals left by extrusion of rhabdites.…”