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Cytoskeletal components and calibers in developing fish Mauthner axon ( Salmo gairdneri Rich )
Author(s) -
Alfei L.,
Albani L. Medolago,
Mosetti A. R.,
Scarfo C.,
Stefanelli A.
Publication year - 1991
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.903140115
Subject(s) - mauthner cell , axon , biology , neurofilament , anatomy , microtubule , caliber , medial longitudinal fasciculus , cytoskeleton , metamorphosis , salmo , neuroscience , microbiology and biotechnology , larva , central nervous system , fish <actinopterygii> , midbrain , cell , materials science , genetics , ecology , immunohistochemistry , fishery , metallurgy , immunology
Abstract In developing axons of many vertebrates, microtubular density is inversely correlated with fiber caliber. It is suggested that microtubules are causally related to axonal caliber. For this reason, cytoskeletal analysis during development of the fish Mauthner axon, which displays a giant caliber, is of particular interest. The Mauthner axon originates from the Mauthner cell in the medulla and runs in the fasciculus longitudinalis medialis in the spinal cord. At embryonic, larval and postlarval stages in trout ( Salmo gairdneri Rich. ), the following parameters were measured on conventional electron micrographs of Mauthner axon cross sections: axonal caliber, number of microtubules per axons, and microtubular and neurofilament densities. Results at each stage point to an inverse correlation between axonal caliber (x) and microtubular density (y) expressed by the equation y = ax b (R = 0.932). Furthermore, three periods of Mauthner axon development are identified on the basis of the cytoskeletal content: (1) embryonic; the Mauthner axon has small caliber with a high microtubule density, (2) elongation period (larval stages); the axon enlarges and a transient peak of microtubules, corresponding to the caliber increment, is observed, and (3) postlarval; the axon enlarges still further (<500 μm 2 ) but has the lowest microtubular content. During this period neurofilaments are the main axonal component.