Histological examination of pancreatic parenchymal changes induced by an experimental fractionated local exposition to X-rays

After exposition to a total dose of 8,000 R delivered with 16 fractions, the pancreatic parenchymal changes in rats were investigated using histological and histochemical techniques. The observations were performed from the first to the 150th day following the last fraction. During the period of acute changes (1st to 15th day), the most part of the acini is morphologically intact, many smaller or greater necrotic foci, however, are to be seen. This is partly due to the enzymes with cytolytic effects, coming from the damaged smaller ducts and from glandular acini. The formation of the other part of the necrobiotic foci originates not only from direct radiation injury, but also from the capillary lesion by radiation. The injury to the wall of greater ducts induces edema, inflammations, dilatation of efferent ductules and stasis, all this leading consequently to an atrophy of the acini associated with the efferent ducts. During the period of chronical changes (50th to 150th day), the number of capillaries diminishes, the necrobiotic foci are multiplied especially in places where no capillaries are visible. This clearly emphasizes the role of the pathological reasons for capillary lesions. The regenerative phenomena occur only to a lesser extent, being confined to the efferent ducts. The extension of the necrotic zones together with the insignificant regeneration leads to a gradual destruction of the tissular substance. It is concluded that the radiosensitivity of the organ can only be determined, if its acute and chronical changes are known. (orig.)