Autoradiography of mast cells in experimental skin tumors of mice injected with radioactive sulfur (S35).

INTRODUCTION In 1937, Holmgren and Wilander (10) main tained that mast cells in connective tissue contain a polysulfuric acid ester giving a heparin effect and that it is their function to secrete the anticoagula tive substance into the blood. This contention is supported by the finding that tissue which is rich in mast cells—e.g., the hepatic capsule of the cow —has more pronounced anticoagulative proper ties than other tissue with a lower content of mast cells—such as the hepatic capsule of the sheep. Moreover, these authors based their view on Lison's (12) opinion that metachromatic staining