Changes in intestinal mucosa above lymph follicles during carcinogenesis in rats: a light and electron microscopic study

Beginning in week 8, dysplastic glands developed in these mucosal areas above the lymph follicles. The number of lymphoid plaques with dysplastic glands in the large intestine increased week by week, attaining 75% in week 20. At the end of week 12 the first adenocarcinoma was detected in the cecum by light microscopy, and classified as a poorly differentiated adenocarcinoma with signet ring cells infiltrating the lymph follicles which contained endocrine cells. The majority of adenocarcinomas (10 cases) occurred in week 20. of these, 7 were localized above the lymphatic plaques in the intestine.