X-ray-induced Abnormal Differentiation of the Epithelium of the Small Intestine in the Mouse

Summary After 2500 r of x-irradiation the cells that originally occupied the crypts (stem cells) migrate onto the villus. These abnormal stem cells form the final protective barrier between intestinal lumen and the tissues. As the population migrates, the cells undergo differential hypertrophy. The more mitotically-active cells in the crypt that are least differentiated show greatest enlargement. The most differentiated and least mitotically-active epithelial cells show least hypertrophy. We propose that stem-cell hypertrophy may be an abnormal form of differentiation, which results primarily from radiation-induced mitotic inhibition.