Cover Picture: Scanning EM image of a corrosion cast of cerebral blood vessels in the auditory region of temporal cortex (in chinchilla). This is a direct view onto the cortical surface, where the large arterial supply and venous return vessels overlie the deeper capillary beds. Regarding the image magnification, the smallest capillaries are ~5 µm in diameter. Strictly speaking, we do not actually see blood vessels but rather the filled space (lumen) inside them. It will be noted that the capillary network is not homogeneously distributed but appears to be dense in some areas and sparse in others. The authors suggest that capillary bed density is related to the metabolic demand of local neural populations, and will be greater in primary sensory areas compared with, for example, association cortex. see Harrison et al., pp. 225-233.
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