Early Postnatal Changes in the Somatodendritic Morphology of Ankle Flexor Motoneurons in the Rat
作者:
Joanna Dekkers,
David L. Becker,
Jeremy E. Cook,
Roberto Navarrete,
期刊:
European Journal of Neuroscience
(WILEY Available online 1994)
卷期:
Volume 6,
issue 1
页码: 87-97
ISSN:0953-816X
年代: 1994
DOI:10.1111/j.1460-9568.1994.tb00250.x
出版商: Blackwell Publishing Ltd
关键词: development;intracellular labelling;confocal microscopy;morphometry;dendritic spines
数据来源: WILEY
摘要:
AbstractThe development of locomotor function in the rat spans the first 3 postnatal weeks. We have studied morphological features of the soma and dendrites of motoneurons innervating the physiological flexor muscles of the ankle, tibialis anterior and extensor digitorum longus, by intracellular injectionin vitrobetween the first and ninth postnatal days. We obtained serial optical sections of 96 adequately filled motoneurons in whole‐mounted hemisected spinal cords by confocal microscopy, projected them onto a single plane and analysed them morphometrically. On the day after birth, the somatodendritic surfaces of most such motoneurons were covered in growth‐associated spiny, thorny or hair‐like appendages. These had disappeared from the soma by the fourth postnatal day and from most proximal dendrites by day 7, but were still common distally on day 9. During this period there was little or no net growth of either the soma (which was still much smaller than in the adult) or the dendritic tree. A dorsal dendritic bias was present and ‘sprays’ of long, loosely bundled dorsal dendrites were often seen. The mean number of primary dendrites remained constant at about eight, and their combined diameter was already significantly correlated with mean soma diameter, as in the adult cat. Thus, the critical neonatal period during which these ankle flexor motoneurons are known to change their electrophysiological properties and to be particularly sensitive to interference with neuromuscular interaction is characterized by major changes in the neuronal surface, presumably linked to synap
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