Part of the central nervous system located in the vertebral canal continuous with and caudal to the brain; demarcated from brain by plane of foramen magnum. It is composed of an inner core of gray matter in which nerve cells predominate, and an outer layer of white matter in which myelinated nerve fibers predominate, and surrounds the central canal. (CUMBO).
Comment:
[homology-note] "(...) at some stage of its development, every chordate exhibits five uniquely derived characters or synapomorphies of the group: (...) (4) a single, tubular nerve cord that is located dorsal to the notochord (...) (reference 1); The neural tube is destined to differentiate into the brain and spinal cord (the central nervous system) (reference 2).[well established][VHOG]" xsd:string {date_retrieved="2012-09-17", external_class="VHOG:0000601", ontology="VHOG", source="ISBN:978-0030223693 Liem KF, Bemis WE, Walker WF, Grande L, Functional Anatomy of the Vertebrates: An Evolutionary Perspective (2001) p.28, ISBN:978-0072528305 Kardong KV, Vertebrates: Comparative Anatomy, Function, Evolution (2006) p.165", source="http://bgee.unil.ch/"}