Development of the corticospinal tract in the mouse spinal cord: A quantitative ultrastructural analysis

Jung Yu C Hsu, Stuart A. Stein, Xiao-Ming Xu

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

The growth of corticospinal tract (CST) axons was studied quantitatively at the 7th cervical (C7) and the 4th lumbar (L4) spinal segments in the balb/cByJ mice at the ages of postnatal day (P) 0, 2, 4, 6, 8, 10, 14, and 28. The cross-sectional area of the CST increased progressively with time. Unmyelinated axons, the most prominent CST element during early development, reached maximum at C7 and L4 on P14. Two phases of increase in the number of unmyelinated axons were observed at C7, while only one surge of axonal outgrowth was found at the L4 level. Pro-myelinated axons, defined as axons surrounded by only one layer of oligodendrocytic process, were first seen at P2 and P4 in the C7 and the L4 level, respectively, followed by a dramatic increase in the number of myelinated axons from P14 onwards at both spinal levels. Myelination of the CST axons occurred topographically in a dorsal-to-ventral pattern. The number of growth cones increased rapidly at the C7 level to reach its maximum at P4, while those at L4 increased steadily to the peak at P10. Growth cones with synapse-like junctions were occasionally observed in the growing CST. Degenerating axons and growth cones partly accounted for the massive axon loss at both spinal segments during CST development. Overall, the mouse CST elements changed dynamically in numbers during postnatal development, suggesting a vigorous growing and pruning activity in the tract. The mouse CST also showed a similar growth pattern to that of the rat CST.

Original languageEnglish (US)
Pages (from-to)16-27
Number of pages12
JournalBrain Research
Volume1084
Issue number1
DOIs
StatePublished - Apr 21 2006
Externally publishedYes

Fingerprint

Pyramidal Tracts
Axons
Spinal Cord
Growth Cones
Growth
Synapses

Keywords

  • Axon
  • Corticospinal tract
  • Electron microscopy
  • Growth cone
  • Myelination

ASJC Scopus subject areas

  • Neuroscience(all)
  • Clinical Neurology
  • Developmental Biology
  • Molecular Biology

Cite this

Development of the corticospinal tract in the mouse spinal cord : A quantitative ultrastructural analysis. / Hsu, Jung Yu C; Stein, Stuart A.; Xu, Xiao-Ming.

In: Brain Research, Vol. 1084, No. 1, 21.04.2006, p. 16-27.

Research output: Contribution to journalArticle

@article{afb42adfbb88401cb3eb3d2bbf9e7f8d,
title = "Development of the corticospinal tract in the mouse spinal cord: A quantitative ultrastructural analysis",
abstract = "The growth of corticospinal tract (CST) axons was studied quantitatively at the 7th cervical (C7) and the 4th lumbar (L4) spinal segments in the balb/cByJ mice at the ages of postnatal day (P) 0, 2, 4, 6, 8, 10, 14, and 28. The cross-sectional area of the CST increased progressively with time. Unmyelinated axons, the most prominent CST element during early development, reached maximum at C7 and L4 on P14. Two phases of increase in the number of unmyelinated axons were observed at C7, while only one surge of axonal outgrowth was found at the L4 level. Pro-myelinated axons, defined as axons surrounded by only one layer of oligodendrocytic process, were first seen at P2 and P4 in the C7 and the L4 level, respectively, followed by a dramatic increase in the number of myelinated axons from P14 onwards at both spinal levels. Myelination of the CST axons occurred topographically in a dorsal-to-ventral pattern. The number of growth cones increased rapidly at the C7 level to reach its maximum at P4, while those at L4 increased steadily to the peak at P10. Growth cones with synapse-like junctions were occasionally observed in the growing CST. Degenerating axons and growth cones partly accounted for the massive axon loss at both spinal segments during CST development. Overall, the mouse CST elements changed dynamically in numbers during postnatal development, suggesting a vigorous growing and pruning activity in the tract. The mouse CST also showed a similar growth pattern to that of the rat CST.",
keywords = "Axon, Corticospinal tract, Electron microscopy, Growth cone, Myelination",
author = "Hsu, {Jung Yu C} and Stein, {Stuart A.} and Xiao-Ming Xu",
year = "2006",
month = "4",
day = "21",
doi = "10.1016/j.brainres.2006.02.036",
language = "English (US)",
volume = "1084",
pages = "16--27",
journal = "Brain Research",
issn = "0006-8993",
publisher = "Elsevier",
number = "1",

}

TY - JOUR

T1 - Development of the corticospinal tract in the mouse spinal cord

T2 - A quantitative ultrastructural analysis

AU - Hsu, Jung Yu C

AU - Stein, Stuart A.

AU - Xu, Xiao-Ming

PY - 2006/4/21

Y1 - 2006/4/21

N2 - The growth of corticospinal tract (CST) axons was studied quantitatively at the 7th cervical (C7) and the 4th lumbar (L4) spinal segments in the balb/cByJ mice at the ages of postnatal day (P) 0, 2, 4, 6, 8, 10, 14, and 28. The cross-sectional area of the CST increased progressively with time. Unmyelinated axons, the most prominent CST element during early development, reached maximum at C7 and L4 on P14. Two phases of increase in the number of unmyelinated axons were observed at C7, while only one surge of axonal outgrowth was found at the L4 level. Pro-myelinated axons, defined as axons surrounded by only one layer of oligodendrocytic process, were first seen at P2 and P4 in the C7 and the L4 level, respectively, followed by a dramatic increase in the number of myelinated axons from P14 onwards at both spinal levels. Myelination of the CST axons occurred topographically in a dorsal-to-ventral pattern. The number of growth cones increased rapidly at the C7 level to reach its maximum at P4, while those at L4 increased steadily to the peak at P10. Growth cones with synapse-like junctions were occasionally observed in the growing CST. Degenerating axons and growth cones partly accounted for the massive axon loss at both spinal segments during CST development. Overall, the mouse CST elements changed dynamically in numbers during postnatal development, suggesting a vigorous growing and pruning activity in the tract. The mouse CST also showed a similar growth pattern to that of the rat CST.

AB - The growth of corticospinal tract (CST) axons was studied quantitatively at the 7th cervical (C7) and the 4th lumbar (L4) spinal segments in the balb/cByJ mice at the ages of postnatal day (P) 0, 2, 4, 6, 8, 10, 14, and 28. The cross-sectional area of the CST increased progressively with time. Unmyelinated axons, the most prominent CST element during early development, reached maximum at C7 and L4 on P14. Two phases of increase in the number of unmyelinated axons were observed at C7, while only one surge of axonal outgrowth was found at the L4 level. Pro-myelinated axons, defined as axons surrounded by only one layer of oligodendrocytic process, were first seen at P2 and P4 in the C7 and the L4 level, respectively, followed by a dramatic increase in the number of myelinated axons from P14 onwards at both spinal levels. Myelination of the CST axons occurred topographically in a dorsal-to-ventral pattern. The number of growth cones increased rapidly at the C7 level to reach its maximum at P4, while those at L4 increased steadily to the peak at P10. Growth cones with synapse-like junctions were occasionally observed in the growing CST. Degenerating axons and growth cones partly accounted for the massive axon loss at both spinal segments during CST development. Overall, the mouse CST elements changed dynamically in numbers during postnatal development, suggesting a vigorous growing and pruning activity in the tract. The mouse CST also showed a similar growth pattern to that of the rat CST.

KW - Axon

KW - Corticospinal tract

KW - Electron microscopy

KW - Growth cone

KW - Myelination

UR - http://www.scopus.com/inward/record.url?scp=33646398881&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33646398881&partnerID=8YFLogxK

U2 - 10.1016/j.brainres.2006.02.036

DO - 10.1016/j.brainres.2006.02.036

M3 - Article

C2 - 16616050

AN - SCOPUS:33646398881

VL - 1084

SP - 16

EP - 27

JO - Brain Research

JF - Brain Research

SN - 0006-8993

IS - 1

ER -