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Cytoarchitecture of spinal‐projecting neurons in the brain of the larval sea lamprey
Author(s) -
Swain Gary P.,
Snedeker Joseph A.,
Ayers Joseph,
Selzer Michael E.
Publication year - 1993
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903360204
Subject(s) - lamprey , mauthner cell , biology , spinal cord , anatomy , neuroscience , cytoarchitecture , horseradish peroxidase , axoplasmic transport , central nervous system , neuroanatomy , fish <actinopterygii> , fishery , biochemistry , enzyme
The descending spinal projecting system of the lamprey is of interest because it includes axons that activate swimming pattern generatorsand because regeneration of this system is involved in the behavioral recovery of lampreys following spinal transection. However, little is known about the true size of this projection and of the distribution of its terminations along the spinal cord. Brain neurons with spinal projections were studied in larval sea lampreys by using wholemount preparations labeled retrogradely with horseradish peroxidase (HRP) from spinal injections at 10%, 15%, 25%, 50%, 70%, and 75% of body length from the anterior end. Neurons projecting to different levels of the spinal cord were mapped. A large number of descending axons terminated within nine segments caudal to the last gill. The spinal projection system was divided into 10 bilateral groups based on cytoarchitectural landmarks. All of the lateral nuclear groups had contralateral spinal projections. In addition to the 12 pairs of Müller cells, the pair of Mauthner cells, and the pair of auxiliary Mauthner cells described by previous authors, the study revealed four pairs of smaller neurons that were individually identifiable. © 1993 Wiley‐Liss, Inc.