The microvasculature of the cerebral white matter: arteries of the subcortical white matter.

The microvascular architecture of the human cerebral subcortical white matter was studied. Most of the subcortical arteries ran straight through the cortex, but upon entering the white matter, they began to coil, loop, and spiral. Vascular stains showed wide spaces between the adventitial sheaths and blood vessels. The blood vessels coiled, looped, and spiraled within these wide adventitial spaces. This phenomenon was observed in the brains from persons ranging from the first to ninth decades of life and there were no statistically significant age-related correlations. Furthermore, there was no evidence of a reduction in the volume of white matter after fixation. Therefore, the observed tortuosity does not appear to be the result of shrinkage of brain tissue following fixation. While the mechanisms responsible for the subcortical arteries circuitry remain undetermined, this coiling architecture may serve as a trap for tumor cells and microorganisms passing through the blood stream, suggesting that these coiling arterial blood vessels may play a significant role in the pathogenesis of tumor metastasis and the brain abscess that frequently occurs in the gray-white matter junction.