TUMOR CELL POPULATION OF THE EHRLICH ASCITES TUMORS

E,hrlich ascites tumor is propagated b?injecting cellh, suspended in ascitic fluid, into the peritoneal cavities of mice. As the cells proliferate an increasing amount of exudate accumulates in the peritoneal cavities. Mice \\lit11 such tumors survive for approsimatelv tu.o to three weeks, depe~iding on the dose of tumor cells. Ehrlich ascites tunlor has been propagated under laboratory conditions longer than anJr other ascites tumor. Its origin can be traced to one or another of nine solid transplantable tumors of mice nlhich Ehrlich described in 1905. Follo\i.ing \!cars of serial transplantation under various conditions and in different stiains of mice or other animals, a number of sublines of the tumor have evolved, all bearing the name 'Ehrlich'. Basicall\., these can be divided into two groups: the ncar-diploid tumor of l,cttrt, \vith a nlodal chron~osome number of 15-46, and the near-tetraploid tumor of Klein, with a modal chromosome nun1t)er betn.ecn 7 5 and 80. N o doubt the Ehrlich ascites tumors available todav in various laboratories still have some similarities but they are not identical. W e became interested in the tumor after Tolnai et al. ( 1962, 1963) demonstrated in the Ehrlich ascites mmor the presence of large cells containing in their cj~toplasm large vacuoles filled \\'it11 a so far unidentified material. These cells c;)i~ld easily be scparated fronl the tumor by high speed centrifugation ( 105,000 X g for 1 hour) after whjch tlwv remained in the supernatant ascites fluid. Subsecluenti\~ it was f o u ~ i d that tliese cells \\,ere not degenerating but activelv proliferating cells (A'lolon~ut et al. 1961; Tolnai 1964) and that the chromosome number varied from 82 180, with no definite modal number; whereas the tumor from \vhich these cells \Yere isolated had a distinct modal chromosome number of 78 (Fedoroff et al. 1964). T h e aim of our studies was to find o i ~ t the origin of the large vocuolated cells with chromosome numbers in the pentaploid range or I~igher.