Morphology on the transplantable gastric carcinoma in WF Osaka rat strain

We have established four lines of transplantable gastric carcinoma in WF Osaka rats. They were derived from adenocarcinomas of the glandular stomach, which were developed along with the lesser curvature, measuring less than 1.0 square centimeter. Morphology of these four lines of the transplantable tumor showed essentially an identical figure in their respective generations. Histology in the early generation of transplanted tumors showed well differentiated tubular adenocarcinoma similar to the primary lesion of the stomach. Later the histological appearance of these four lines of the transplanted tumor altered from glandular structure to keratinizing squamous cell metaplasia of cancer cells. The lines of S4 and S5 transplantable tumor were recently established, but the lines of S1 and S3 transplantable tumor have been transplanted as far as more than the 60th generation, and changed their histological appearance to scirrhous carcinoma in the line of S1 and medullary carcinoma in the line of S3. The growth speed of S1 line became slow in the later generations compared to the former ones, and that of S3 line became extremely rapid and recipient rats died with cachexia within two weeks. Effectual activities of tumor enhancement for the gastric and the colon cancer, previously reported elsewhere, recently decreased, and gastric carcinoma was rarely induced by these two lines. Lately established S4 and S5 transplantable tumor lines showed vigorous flourish of inducing gastric and colon cancers.