title: The early scaffold of axon tracts in the brain of a primitive vertebrate, the sea lamprey.
abstract: The development of the early axonal scaffold formed by early-differentiating neurons was studied in a primitive vertebrate (the sea lamprey), by immunohistochemistry against acetylated alpha-tubulin and a cell surface marker (HNK-1 antibodies), to determine the degree of conservation of this process in vertebrate evolution. The medial and dorsolateral longitudinal fascicles were the first longitudinal axonal bundles observed to develop in the neural tube, followed by the tract of the postoptic commissure and the supraoptic tract. Establishment of the first dorso-ventral tracts occurs after the appearance of the tract of the postoptic commissure and the medial longitudinal fascicle, the basal plate longitudinal axonal system. The dorsolateral longitudinal fascicle appears to be equivalent to the "descending tract" of the mesencephalic nucleus of the trigeminal nerve of mouse and birds; the possible homologies between other early scaffold tracts of the sea lamprey and those of other vertebrates are also discussed. In addition, present results suggest the presence of highly conserved brain regions that would allow for early neuronal differentiation and axonal pathfinding in vertebrates, which were probably defined before the divergence of Agnathans and Gnathostomes.
authors.affiliation: Department of Cell Biology and Ecology, Faculty of Biology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: Antón
authors.initials: A
authors.lastname: Barreiro-Iglesias
authors.forename: Begoña
authors.initials: B
authors.lastname: Villar-Cheda
authors.forename: Xesús-Manoel
authors.initials: XM
authors.lastname: Abalo
authors.forename: Ramón
authors.initials: R
authors.lastname: Anadón
authors.forename: María Celina
authors.initials: MC
authors.lastname: Rodicio
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism / Q000502:physiology*; D001921:Brain / Q000166:cytology / Q000196:embryology / Q000254:growth & development; D018959:CD57 Antigens / Q000378:metabolism; D004625:Embryo, Nonmammalian; D007814:Larva; D009434:Neural Pathways / Q000502:physiology; D048428:Petromyzon / Q000033:anatomy & histology / Q000196:embryology / Q000254:growth & development; D014404:Tubulin / Q000378:metabolism
chemical_list: D018959:CD57 Antigens; D014404:Tubulin