Tooth Germs Transplanted with Human Brain Tumor **†

The demands for energy-rich metabolites by particular organs during prenatal growth and development are so great that the entire resources of the embryo are mobilized at specific times." There is an increased rate of activity of the major metabolic pathways during embryonic development on demand by particular sites. The product or result of this particular activity is growth of the organ or organs in question, and the requirements of the anlagen of teeth during the formation of the pre-enamel and pre-dentine matrices are no different."" During such times any environmental insult resulting in a lack of available metabolites may produce congenital anomalies in those teeth upon which the embryo is at that time concentrating. "' Tumors consume large amounts of energy for they have a higher aerobic and anaerobic glycolysis than most normal tissues.''1' Warburge states that tumor cells utilize the energy of carbohydrate breakdown from a synthesis of cellular proteins to a larger extent than most normal tissues. In transplanting spontaneous mammary tumors with normal tissues of different strains of mice, Browning' observed there was for a time a stimulation of the normal tissue growth. As the alien tumor cells began to invade the growing embryonic homotransplants, focal concentrations of lymphocytes appeared which aided growth of the embryonic tissues by destroying the tumor cells. In studying the interaction between transplanted normal and malignant suspensions of cells, Schneyer17 did not obtain results similar to Browning. Oker-Blom and Alfthane had sporadic success with normal and neoplastic tissues dually transplanted to the chorio-allantoic membrane. It was observed by Malmgren's et aL' that inter-strain tumor transplants failed to survive in tumors of a different genetic derivation, but when they