Host: The Japanese Society of Toxicology
Name : The 49th Annual Meeting of the Japanese Society of Toxicology
Date : June 30, 2022 - July 02, 2022
Carcinogenicity studies using rasH2-Tg mice may be hesitant to conduct due to lack of knowledge for background data and testing experience. In this presentation, I would like to present the pathological background and characteristic lesions to increase understanding of rasH2-Tg mice and to promote their use.
The standard 26-week carcinogenicity study using rasH2-Tg mice consists of 25 males and 25 females per group, 3 dose groups, a negative control group (NC), and a positive control group (PC) that receives a known carcinogen such as MNU or urethane to validate the test system. In our background data, the survival rate at week 26 was 98%/94% (male/female) for NC and 6%/22% for PC (MNU), and there was no significant difference in the transition of body weight from 1 to 26 weeks between NC and PC.
At necropsy, in the PC, the forestomach mass in almost all, and the skin mass, thoracic fluid, and enlargement in the thymus, lymph nodes and spleen in more than half were observed.
Histopathologically, in the NC, hemangioma or hemangiosarcoma of the spleen, adenoma or adenocarcinoma of the lungs, and squamous cell papilloma (SCP), keratoacanthoma (KA) or squamous cell carcinoma (SCC) of the skin were observed in a few. In the PC, the forestomach tumor (SCP or SCC) in almost all, malignant lymphoma of the lymphohematopoietic system in more than 3 quarters, and the skin tumor (SCP, KA or SCC) in about half were observed. SCP of the vagina and adenoma of the uterus were observed in a few cases. In my presentation, I will report these background data in detail.
