Effect of thermal environment upon transplanted tumors and growth of mice

Abstract

Ehrlich ascites tumor cells were inoculated subcutaneously in the dorsal, interscapular region of three groups of mice that were subsequently maintained in normo-, hypo- or hyperthermic environments. The controls, mice that had homologous whole spleens or thymic glands implanted in the same location, were maintained in a normothermic environment. Number of tumors established, their weights and volumes, and weights of animals were compared as well as tumor temperature, which was compared to brown fat and core temperatures. (1) The percentage of animals developing tumors was independent of environment. (2) Mice with tumors, and mice in which tumors did not take, gained more weight at the normothermic temperatures (21 °C) than at either 31 or 5 °C. (3). When the weight and volume of tumors are expressed per gram of mouse body weight, there is no difference between the hypo- and normothermic environments, but the weights and volume of tumors in a hyperthermic environment are only 36 and 58% respectively of the tumors in normothermic animals. (4) Tumor temperatures are about 1 °C cooler than the underlying brown fat regardless of environment, and brown fat was 0.5 °C cooler than the core temperature. (5) Transplanted thymus glands and spleens become encysted after 31 days; they proved to be cooler than the malignant tumors.