Comparative biochemical and ultrastructural studies of capillaries from normal humans, normal mice, and human cerebral astrocytomas.

Capillaries from cerebral white matter were isolated from normal humans and normal mice and from human astrocytomas (Grades II-IV) to investigate potential biochemical and ultrastructural differences between normal and neoplastic-derived microvessels. Capillaries from Grade III and IV astrocytomas averaged 55-fold higher in the concentration of total protein than capillaries from normal mouse and normal human cerebral tissues. Scanning electron microscopic examination revealed more bifurcations and fewer surface undulations in the capillaries derived from anaplastic astrocytomas than in capillaries derived from normal specimens. Sprouting configurations were detected in the capillaries from anaplastic astrocytomas. They measured 4 to 5 micron in diameter and manifested fewer surface undulations than capillaries from normal human white matter. The results of these preliminary investigations suggest early capillary growth from parent vessels in high-grade and highly vascularized astrocytomas.