IN VIVO STUDY ON THE PROCESS OF SOLID TUMOR FORMATION FROM EMBRYOID BODIES OF MOUSE TERATOCARCINOMA

Embryoid bodies of mouse teratocarcinoma OTT 6050 were studied with special reference to their growth and differentiation in vivo. They were grown either in the peritoneal cavity or in the lung. When injected intraperitoneally, embryoid bodies doubled their number every three days. Some of them attached to a small intra-peritoneal fat body and were soon surrounded by mesenchymal cells of host origin. They grew, fused with each other and became large solid tumors which contained many differentiated tissues. When injected intravenously, almost all the embryoid bodies lodged in the lungs and individually grew into discrete solid tumors which doubled in volume every 2.9 days. After about thirty days, some tumors were composed of only one type of tissue while others contained several types of tissues. The possible mechanisms for the uni- and multi-tissue types of differentiation are discussed.