Experimental adenomas and carcinomas of the large intestine behave as distinct entities: Most carcinomas arisede novo in flat mucosa

摘要: Detailed histologic analyses were performed on tumors of the large intestine obtained in 152 dimethylhydrazine(DMH)-treated rats. Of a total 539 glandular neoplasms, 45 benign; 494 (92%) locally invasive; which 222 (41%) invading muscularis propria. One-hundred-forty-one ≧3mm diameter. Among those, 127 (90%) invasive. In addition to macroscopic nodules, several microscopic carcinomas observed serial sections flat mucosa. The benign polyps usually appeared after longer latency periods than did carcinomas. A review literature indicates that majority rat experiments most or all DMH-induced invasive carcinomas, often absence adenomas. Microscopic frequently reported. All these data constitute strong evidence experimental adenocarcinomas do arise de novo mucosa, i.e., without prior adenoma stage. However, mice reported be adenomas, either alone coexisting with It is suggested “de arising carcinomas” and adenomatous polyps, are both inducible by same carcinogens, can coexist some systems, nonetheless independent distinct pathologic entities; they separated genetic susceptibility.