Ultrastructure of the vasculature of central nervous system tumors of childhood.

Developing cell systems involving the central nervous system are ultimately dependent upon acquisition of a vascular supply for continued growth. Tumor cells proliferate to a critical mass beyond which metabolic exchange cannot be maintained by diffusion alone. The growth of this blood supply is stimulated by the tumor and grows into the cell mass from the surrounding brain. These 'tumor vessels' have anomalies of structure and function which explain many pathological changes seen in brain tumors and probably have therapeutic significance. 83 primary brain tumors were obtained at surgery and studied with the electron microscope with particular emphasis on the structure of the microvasculature. Open junctions, fenestra, and increased pinocytosis were seen in almost all tumors. The basal lamina was thickened and usually multilayered. The perivascular space was large and contained a dense granular material which usually spread into the surrounding extracellular space of the tumor. The more malignant the tumor, the more frequent were these changes.