Morphological Characteristics of Colon Tumors in Mice with Different Tolerance to Hypoxia

In adult male C57BL/6 mice with high (HR) and low (LR) resistance to hypoxia, morphological features of colon tumors and blood parameters were evaluated 70 days after intraperitoneal injection of azoxymethane and subsequent consumption of 3 cycles of dextran sulfate sodium. On macroscopic analysis, tumors were found in the distal colon in 35% (7 of 20 animals) of HR and 31% (4 of 13 animals) of LR animals. Microscopic analysis of the distal colon revealed tumors in 75% (15 of 20 animals) of HR and 69% (9 of 13 animals) of LR mice. The tumors were presented by areas of glandular intraepithelial neoplasia and adenocarcinomas; the incidence and the area of the tumors did not differ in groups of HR and LR mice. The number of neuroendocrine and goblet cells in the distal colon mucosa in the areas of tumors was similar in the compared groups. However, in both HR and LR mice of the experimental groups, the content of goblet cells in tumors was lower and the content of endocrine cells was higher than in the corresponding control groups. In the peripheral blood, the erythrocyte count and hemoglobin content decreased in HR and LR mice of the experimental groups; the relative number of monocytes increased only in HR mice and the absolute number of lymphocytes and monocytes decreased in LR mice. Thus, 70 days after azoxymethane administration and dextran sulfate sodium consumption, the tumors in mice were presented by glandular intraepithelial neoplasia and adenocarcinomas, and their incidence and area did not differ between animals with different tolerance to hypoxia.