[Ischemic lesions and post-ischemic regeneration of the small intestinal mucosa].

After ligationof the vascular arcades of the upper jejunum in rats ischemic damage to the intestinal mucosa and its regenerative behavior were investigated by histology, morphometry, enzyme-histochemistrym, autoradiography and electron microscopy. The process of ischemic damage begins at the tips of the villi and progresses to the crypts. After ischemia lasting 300 min the mucosa, submucosa and muscularis propria are necrotic, which means, that the small intestine is at this time completely infarcted. Whilst sthe ischemic damage to the crypt epithelia is similar to that of other kinds of epithelia, the ischemic damage to the enterocytes is different. The enterocytes are shed to the intestinal lumen without any signs of irreversible damage by a blebformation at their cell base. After 2 h ischemia -- the basal epithelia of the crypts are not irreversible damaged yet at this time--and a 12 h period of restored blood flow, the mucosal surface is completely covered again by a flat epithelium. This is achieved 1) by an above-normal proliferation of the epithelia derived from the residual crypts, 2) by the appearance of flat epithelia with an increased diameter. After 8 days of repair the small intestinal mucosa shows morphologically, autoradiographically and enzyme-histochemically a normal picture again.