[Animal Modeling]-Pathological observation of spontaneous tumors in old SD rats

  Purpose: To observe the development of spontaneous tumors in SD rats and provide background information for the development of new drugs on carcinogenicity.

   Method: In the carcinogenicity study, there were 120 4-week-old SPF SD rats in the normal control group, half of which were males and half were males. They were observed for 1 week before the experiment and euthanized after 104 weeks of routine feeding. Rats that died and were sacrificed in the experiment were dissected and weighed, including heart, lung, liver, spleen, kidney, adrenal gland, thymus, brain, testis, epididymis (or uterus) and normal diseases. Ready to use an optical microscope. Observe the types and incidence of spontaneous tumors in various organs.

  Result: A total of 113 SD rats were observed (7 were lost during the experiment). Rats affected by tumors accounted for 66.4% (75/113), of which benign tumors accounted for 48.7% (55/113) and malignant tumors accounted for 17.7% (20/113). The proportion of tumors in male rats was 49.1% (28/57), of which 50.9% (26/57) were benign tumors and 3.5% (2/57) were malignant tumors. The main benign tumor was pituitary adenoma (pituitary gland). Tumor) (36.8%). Large-scale adrenal medullary adenoma (7.0%), malignant tumors are mainly thyroid adenocarcinoma (18%) and fibrosarcoma (1.8%). The incidence of tumors in female rats was 83.9% (47/56), of which 51.8% (2956) were benign tumors, 32.1% (18/56) were malignant tumors, and the main benign tumor was pituitary adenoma (50.0%). ) And breast fibroadenoma. (12.5%) and breast adenoma (12.5%). Malignant tumors are mainly breast adenocarcinoma (25.0%) and fibrosarcoma (3.6%).

   Conclusion: The incidence of spontaneous and benign tumors in SD rats with normal growth over 2 years old is higher than that of malignant tumors, which are related to aging, tumors and individual differences.