A transplantable rat tumor

Abstract A transplantable rat sarcoma arising in a colony of ovariectomized rats used for the assay of estrogens has been investigated. The tumor was transmitted by transfer of tissue fragments or by inoculation of a suspension of tissue. Bacteriologic examinations were negative and the tumor was not transmitted by filtrates of tumor tissue. The tumor was carried on in eleven lines: three lines for 10 generations, one each for 12, 17, and 19 generations, two each for 21 and 22, and one for 24. No line died out spontaneously. No tumors regressed. The tumor remained characteristic regardless of the site of transfer and did not change type at any time. The transplantability increased with repeated transfer. Of the 1,171 transfers made by intraperitoneal inoculation, 839 (71.7 per cent) were successful irrespective of the amount of tissue transferred. In a group of 436 hosts which received 100 mg. of tumor tissue, 353 hosts (81.0 per cent) developed tumors. Eighty and eight-tenths per cent of the male hosts (257 of the 318 hosts) showed successful transfers and 81.4 per cent of the female hosts (96 of the 118 hosts), indicating no sex difference in the susceptibility of the hosts to the tumor. In a group of 383 hosts which received 100 mg. of tumor tissue, 318 (83 per cent) were successful. Of these, 43 hosts (13.5 per cent) survived less than 20 days, 136 hosts (35.5 per cent) survived 20 to 29 days, and 139 hosts (36.3 per cent) survived longer than 30 days. The sites of the tumor development in a group of 179 hosts receiving 100 mg. of tumor tissue intraperitoneally and surviving less than 30 days were: omentum 176, liver and adjacent tissues 171, genital fat 156, implants 198, mesentery 149, diaphragm 91, subcutaneous 53, intestinal tract 23, kidney and adjacent tissues 14, spleen 4, thoracic cavity 3, and stomach 1. Other sites of tumor formation observed were the ovary, testis, seminal vesicle, thymus, lymph nodes, heart, and lung. Ascitic fluid accompanied advanced tumors. The greatest number of sites of tumor formation in one host was ten. Forty-seven of the 179 hosts (26.3 per cent) showed tumors in seven sites. One hundred and fifty-six hosts (87.1 per cent) had tumors in four to eight sites. Amounts of tumor tissue from 0.5 to 100 mg. were transferred. The group of hosts receiving 40 mg. or less showed a slightly lower percentage of “takes” than those receiving 50 or 100 mg. of tissue. The transplantability of the tumor increased with repeated transfers. Three chronological groups of male hosts composed of 31 groups of three hosts each received transfers from 92 tumors. The earliest group showed 72 per cent successful transfers, the second group 79.6 per cent and the latest group 90.3 per cent. Three experiments were carried out to determine the mode of transmission and the rate of development of the transfers. A large group of hosts was inoculated and small groups were sacrificed at weekly intervals. Tumor development at the various intervals is described. Tumors were observed at seven days. The effect of tumor growth on the estrus cycle and upon the ovaries has been investigated. Several experiments were un lertaken to determine the effect of the tumor upon fertility and the course of pregnancy, and of pregnancy upon the tumor development.