The interaction between Walker tumour cells and mucosa cells in the lamina propria of gastric mucosa in rats. The tumour behaviour in previously X-irradiated mucosa compared to normal mucosa.

Abstract

One series of 12 rats was exposed to X-irradiation (1500 R) of the stomach 19 days before implantation of Walker tumour cells in the gastric mucosa, and the frequency of tumour take and the extent of tumour growth after 10 days were compared with a second series with the same tumour implantation, but without X-ray exposure. In a third series simple gastric ulcers without tumour were produced by clamping the gastric wall with a heated (80 degrees) surgical needle holder, and the animals were killed 5-7 day later. All the rats were given injections of vinblastine sulfate 3 hours and of 3H-TDR 1 hour before sacrifice. In viewfields with diameter 180 mu the vinblastine-arrested mitoses and labelled cells on the tumour side of the tumour/mucosa border were calculated as percentages of all tumour cells. In the mucosa the total number of proliferating cells was counted at various distances from the border of the tumour or ulcer. No clear differences in the frequency of tumour take and the extent of tumour growth were found between the X-irradiated and the normal rat stomachs, and it is concluded that the X-ray exposure 3 weeks prior to tumour implantation did not reduce the normal mucosal resistance to tumour growth. The percentage of arrested mitoses and labelled cells in the tumour decreased one view field away from the mucosal border, and the number of proliferating cells in the mucosa bordering on the tumours showed a gradual fall with increasing distance up to 0.8-1.0 mm from the tumour border; within these distances, however, the numbers were much higher than at corresponding distances from edges of the ulcers. The Walker tumour thus seems to stimulate cell proliferation in mucosa to a much greater extent than a simple ulcer does. The causes of this phenomenon and the possible roles of "chalones" or "anti-chalones" are discussed.