OBSERVATIONS ON THE SERIAL TRANSPLANTATION AND GROWTH CHARACTERISTICS OF THE ITB ASCITES TUMOR OF THE RAT1

SUMMARY When transplanting the ITB tumor by means of ascitic fluid, in which the number of tumor cells was small at first in comparison with that of inflammatory cells, the number of the tumor cells contained in the ascitic fluid rose gradually during the process of transplantation until, from the seventh generation onwards, the neoplasm began to grow in the way typical of ascites tumors. The developed ITB ascites tumor has now been transferred through 100 generations. The rate of successful transplantation has been 82 per cent. The properties of growth, the morphology of the tumor cells in the ascitic fluid, and the histological features of the solid tumor infiltration have remained unchanged during the process of transplantation. Inoculation of tumor cells produced an initial polymorphonuclear response in the peritoneal cavity followed by proliferation of mononuclear inflammatory cells. The tumor cells began to increase greatly in number after the second day, until on the sixth the ascitic fluid was an almost pure culture of tumor cells. Regressive changes were seen in the tumor cell proliferation soon after this, the relative number of the tumor cells showing a remarkable fall during the terminal phase of tumor development. In connection with the ITB ascites tumor there is solid tumor growth in the peritoneal cavity which is very abundant during the terminal phase. Infiltration of the omentum by tumor cells begins 2–3 days after inoculation.