[Ultrastructure of capillary permeability in human brain tumors. Part 1: Gliomas associated with cerebral edema (low density area)].

In order to elucidate pathogenesis of perifocal edema in the human brain tumors, we observed the alteration of capillary permeability between the glioblastomas with remarkable edema (4 cases) and astrocytoma with slight edema (3 cases). Specimens were studied by conventional ultrathin section and freeze-fracture replica technique. In ultrathin sections of capillaries in glioblastomas, some of these cell junctions were tortuous, elongated, in fact, open. Other capillary abnormalities included endothelial hyperplasia with extensive vesicular formation, surface infolding of endothelial cells, irregularity of the basal lamina and the presence of a large collagen filled extracellular space. In freeze-fracture replicas of capillary endothelium, pinocytotic vesicles markedly increased and were an average fo 52 per micron. Tight junction in one area was seen as network of 6 strands composed of about 100A particles, but in the other areas as one or two strands. In ultrathin sections of astrocytoma, yet there were blood vessels appeared relatively normal. In freeze-fracture replicas, pinocytotic vesicles markedly increased and were an average of 34 per micron. Tight junction was seen as network of 7 strands. We concluded that fewer strands of the tight junction play an important role in increasing the permeability in the vessels of glioblastomas with severe perifocal edema, in addition to increasing the pinocytotic vesicles.