The histochemical behaviour of zinc-activated tartrate-resistant phosphatase (ZnTP) in early stages of experimental tumors in the rat trigeminal nerve.

The activity of the ZnTP (Felicetti und Rath 1975; Rath and Felicetti 1975) was investigated histo- and biochemically in neurinomas of trigeminal nerves of rats. The tumors were induced by a single transplacental pulse of 30 mg ENU/kg on the 17th day of gestation. The rats were killed at the age of 40 to 160 days. The activity of the ZnTP is demonstrated histochemically by a coupling azo dye technique with 1-naphthylphosphate after Rath and Felicetti (1975) as well as a lead nitrate method with 4-nitrophenyl phosphate at the age of 40 to 140 days. Biochemical investigations of the trigeminal nerves are performed at the age of 140 and 160 days only. The separation of ZnTP is carried out by isoelectrofocusing in polyacrylamide gels after Felicetti and Rath (1975). Together 14 neurinomas are found in the trigeminal nerves of 53 rats. All neurinomas show a high activity of the ZnTP. The ZnTP activity is absent in normal Schwann cells. Three trigeminal nerves of rats subjects to the transplacental pulse of ENU harbour small foci of ZnTP activity without detectable neoplastic cell proliferation. Similar spots of enhanced ZnTP activity have never been found in control rats. This rises suspicion that the neoplastic proliferation of cells is preceded by the activation of ZnTP.