[Ultrastructure of blood and lymphatic capillaries of rectal cancer before and after irradiation].

The ultrastructure of blood and lymph capillaries of rectal adenocarcinoma was studied before and after pre-operation radiation therapy. The walls of blood capillaries of the tumor were formed by endothelial cells, basal membrane, and pericytes, while those of lymph capillaries by endothelial cells alone. After irradiation of the tumor at a dose of 20 Gr the total architechtonics of the vessel wall of blood and lymph capillaries was retained, but the lumen of many capillaries became smaller, and connections between endotheliocytes weaker. Radiation changes of endothelial cells of the vessels of both types are similar and manifest as swelling, vacuolation of organelles of the cytoplasm, accumulation of lipid drops, distention of tubules and cisterns.