ROLE OF APOPTOSIS IN MODULATION OF THE GROWTH OF HUMAN COLORECTAL TUBULAR AND VILLOUS ADENOMAS

To estimate the effect of cell proliferation and deletion on the growt h of the human colorectal adenoma, 27 tubular adenomas and eight villo us adenomas were examined. Tubular adenomas were categorized into thre e grades of cellular atypia: mild, moderate, and severe. Villous adeno mas were given a single grade. Morphological characteristics of apopto sis (nuclear condensation and budding) were used to quantify an apopto tic index, AI (percentage of apoptotic cells in viable adenomatous cel ls). The apoptotic cells were found mainly among the basal site of the adenomatous tubules. The AIs of tubular adenomas with mild, moderate, and severe grades of atypia were 3.5, 5.7 and 8.8 per cent, respectiv ely. The AI of villous adenomas was 1.8 per cent, which was significan tly lower than that of tubular adenomas. The mitotic indices, MIs (per centage of mitotic cells in viable adenomatous cells) of tubular adeno mas were 0.41 per cent (mild), 0.58 per cent (moderate), and 0.83 per cent (severe), and for villous adenomas the MI was 0.38 per cent. Ther e was a close positive relationship between the AI and MI of tubular a denomas, which paralleled the grade of atypia. These results indicate that both cell proliferation and death were more frequent in adenomas with severe atypia than in adenomas with mild atypia. Moreover, the si gnificantly lower AI of villous adenomas, known to develop into large tumours when compared with tubular adenomas, suggests that reduced apo ptoses may lead to a shift in tissue kinetics towards expansive growth .