Adv Anat Embryol Cel
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Adv Anat Embryol Cel · Jan 2000
Review Comparative StudyDevelopment and regenerative capacity of descending supraspinal pathways in tetrapods: a comparative approach.
Throughout tetrapods a basic pattern in the organization of descending supraspinal pathways is present. The most notable difference between nonmammalian tetrapods and mammals is the apparent absence of somatomotor cortical areas giving rise to long descending projections to the spinal cord. The phylogenetic constancy of descending supraspinal pathways, at least of those arising in the brain stem, probably implies a comparable pattern of development, presumably a developmental sequence in the formation of these central motor pathways. ⋯ A special case is presented by anurans which in fact have two motor systems, a primary, transient motor system and a secondary, definitive motor system. Reticulospinal, interstitiospinal and vestibulospinal fibers innervate the spinal cord very early in development, well before the development of the hindlimbs. Rubrospinal fibers in