The evolution of the brain in vertebrates has created irreversible rearrangements in the basic segmental logic of vascular architecture. However, the way the spinal cord and the brain are supplied still will have many analogies (Bugge 1974). Although the spinal cord is not a primitive brain, the neural tube vascularization will have a certain craniocaudal outline, at least for a few days. As can be seen with the spinal cord (see Chap. 2), the neural crest derivatives induce most of the early vascular changes towards the future central nervous system. As a result, the segmental arterial network follows the nerves whether cranial or spinal, but it would be a mistake to compare this budding system to a growing tree. A segmental system and a pial network develop rapidly and simultaneously. To simplify, one can distinguish a distributing system specific to the neural tube (pial or subpial) from a source of supply system which corresponds to the segmental system or its equivalent.
KeywordsMigration Ischemia Germinal Assimilation Peri
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