Table 1.

Summary of abnormalities developing in 3C7 mice

Age (weeks)	Lung	Heart	Colon	Number of processed mice
4–6	Mild emphysema	Normal	Mucosal prolapse syndrome of  the rectum	18
12–14	Moderate emphysema, rupture of  septal walls	Moderate cardiomyopathy with  right ventricular dilatation  (cardiac body weight index  increased >10%)	Colorectal adenoma	22
24–32	Severe emphysema with  extensive atelectatic areas	Cardiomyopathy with  biventricular dilatation (cardiac  body weight index increased  >30%)	Invasive colorectal carcinoma	14

All the other inspected organs and tissues were microscopically normal. Analysis included aorta, liver, kidney, intestine, lymph nodes, brain, bone marrow, thymus, adrenals, pituitary, thyroid, pancreas, skin, uterus, and testicles.