Experiments on an ascites hepatoma: II. Intraperitoneal transplantation of free tumor cells separated from islands of the rat ascites hepatoma

Abstract

1. 1. Large numbers of single tumor cells were obtained by a relatively simple procedure based on the ability of trypsin to digest the intercellular cement substance in the islands of the ascites hepatoma. Populations of single cells were then transplanted intraperitoneally into new hosts, where the cycle of redevelopment of a new ascites hepatoma was followed. 2. 2. The viable portion of the original, single tumor cell population did not continue to proliferate as free cells, but reformed tumor islands. Thus, 2 hours after inoculation of the trypsin treated coagulum, free tumor cells represented 99 per cent of the total cell population while the number of tumor cell pairs remained less than 1 per cent. Within 8 to 10 hours after inoculation the tumor cell population was composed of approximately equal numbers of single tumor cells and tumor cell pairs. In a second typical experiment, examination of ascitic fluid was made at intervals from 17–48 hours after inoculation. The count at 48 hours showed about 14 per cent free tumor cells, 42 per cent tumor cell pairs, 17 per cent tumor cell triples and 27 per cent tumor cell islands of 4 or more cells. 3. 3. Observations of several thousand tumor cell pairs counted on Giemsa stained smears indicated that a hepatoma pair may frequently undergo a series of morphological alterations following its formation from a newly divided single cell. The end result is the formation, in many cases, of a tumor pair possessing one crescent-like cell (“endothelial”) and one hepatic cell. 4. 4. The relation of the crescent-like cell to the “endothelial” cell suggested by Yoshida and his co-workers as being implicated in the origin of the Yoshida ascites sarcoma is discussed.