ULTRASTRUCTURAL AND MORPHOMETRIC INVESTIGATION OF HUMAN BRAIN CAPILLARIES IN NORMAL AND PERITUMORAL TISSUES

Capillaries of peritumoral and normal brain tissues were ultrastructur ally and morphometrically investigated to evaluate the changes in peri tumoral capillaries connected with the tumor-associated vasogenic edem a. The endothelial cells of peritumoral capillaries showed varying thi ckness, electron-lucent cytoplasm, and structurally normal tight junct ions. The basal lamina was thickened, rarefied, and vacuolated. The pe ricytes were provided with pinocytotic vesicles and phagocytic bodies. The astrocytic glia appeared empty or swollen, with few glycogen gran ules and a disarranged cytoskeleton; well-preserved glia was occasiona lly observed. The brain tissue was slightly edematous. No statisticall y significant differences were observed between normal and peritumoral capillaries as regards diameter, wall thickness, endothelial thicknes s, and endothelial vesicle density. Instead, the peritumoral capillari es displayed three times as many endothelial surface-connected vesicle s, a markedly thicker basal lamina, and significantly reduced extensio n of pericytic and glial investments. The kind and severity of the vas cular modifications, compared with the slight edematous appearance of the nervous tissue, strengthen the hypothesis that peritumoral capilla ries could be involved in the edema resolution process.