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Morphometric analysis of dendritic remodeling in an identified motoneuron during postembryonic development
Author(s) -
Libersat Frederic,
Duch Carsten
Publication year - 2002
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.10318
Subject(s) - biology , dendrite (mathematics) , manduca sexta , metamorphosis , soma , neuroscience , microbiology and biotechnology , growth cone , anatomy , axon , larva , botany , mathematics , geometry
Abstract A detailed quantitative description of modifications in neuronal architecture is an important prerequisite to investigate the signals underlying behaviorally relevant changes in neuronal shape. Extensive morphological remodeling of neurons occurs during the metamorphosis of holometabolous insects, such as Manduca sexta , in which new adult behaviors develop postembryonically. In this study, a morphometric analysis of the structural changes of an identified Manduca motoneuron, MN5, was conducted by sampling its metric parameters at different developmental stages. The remodeling of MN5 is divided into three main phases. The regression of most larval dendrites (1) is followed by the formation of dendritic growth‐cones (2), and subsequently, adult dendrite formation (3). In contrast, the cell body and link segment surface increase during dendritic regression and regrowth, indicating that different cell compartments receive different signals, or respond differently to the same signal. During dendritic growth‐cone formation, the growth of the cell body and the link segment are arrested. Sholl and branch frequency analysis suggest two different modes of dendritic growth. During a first growth‐cone‐dependent phase, new branch formation occurs at all dendrites. The maximum path length of the major dendritic tree changes little, whereas branch order increases from 20 to 45. Changes in total dendritic length are correlated with strong changes in the number of nodes but with minor changes in the average dendritic segment length, indicating a mode of growth similar to that induced by steroid hormone application to cultured motoneurons. The second phase is growth‐cone‐independent, and branching is limited to high order dendrites. J. Comp. Neurol. 450:153–166, 2002. © 2002 Wiley‐Liss, Inc.