Growth pattern of pioneering chick spinal cord axons

doi:10.1016/0012-1606(87)90396-4

Developmental Biology

Volume 123, Issue 2, October 1987, Pages 375-388

https://doi.org/10.1016/0012-1606(87)90396-4 Get rights and content

Abstract

The early growth pattern of axons in the embryonic chick spinal cord was studied by electron microscopy. Serial perisagittal thin sections were obtained from the lateral margins of spinal cords of stage 17 (S17) and S19 embryos. A simple stereotypic pattern of axonal growth was found. Axons originated from a dispersed population of presumptive interneurons located along the lateral spinal cord margin. They first grew ventrally in a nonfasciculative pattern and later turned at right angles and grew in a fasciculative manner longitudinally in the ventrolateral fasciculus. Growth along the circumferential pathway was analyzed in detail by reconstructing individual axons and growth cones from the S17 specimen. Most circumferential axons, regardless of their site of origin, grew in a parallel orientation, and each of their growth cones projected ventrally. This pattern suggested that circumferential growth cones were guided at many, if not all, points along their path. Study of the region in front of these seven growth cones, however, revealed no apparent structural basis for their guidance. Alternative guidance mechanisms are discussed. In conjunction with previous studies (e.g., Windle and Baxter, 1936; Lyser, 1966), these findings suggest that the circumferential-nonfasciculative and the longitudinal-fasciculative patterns of axonal growth are the two fundamental patterns followed by most early forming axons in the brain stem and spinal cord of all higher vertebrates.

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Holley, J. A., Silver, J., and Lasek, R. J. Growth pattern of pioneering chick spinal cord axons. Unpublished, earlier...

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The commissural axons project toward and across the floor plate. They then turn into the longitudinal axis, extending along the contralateral side of the floor plate. F-spondin, a protein produced and secreted by the floor plate, promotes adhesion and neurite extension of commissural neurons in vitro. Injection of purified F-spondin protein into the lumen of the spinal cord of chicken embryos in ovo resulted in longitudinal turning of commissural axons before reaching the floor plate, whereas neutralizing antibody (Ab) injections caused lateral turning at the contralateral floor plate boundary. These combined in vitro and in vivo results suggest that F-spondin is required to prevent the lateral drifting of the commissural axons after having crossed the floor plate.
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^☆: Portions of this study have been reported elsewhere (Holley and Lasek 1982; Katz and Lasek 1985).

^☆☆: This work was supported by Alexander von Humbolt and NIH fellowships to J.A.H., and NIH grants awarded to J.S. (NS1573-03) and Dr. Lasek (NS07118-03).

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Full paperGrowth pattern of pioneering chick spinal cord axons☆,☆☆

Abstract

Trends Neurosci

Dev. Biol

Dev. Biol

Dev. Biol

Dev. Biol

Dev. Biol

Dev. Biol

Dev. Biol

Dev. Biol

Dev. Biol

The early development of the ventral part of the neural plate of amblystoma

J. Comp. Neurol

Pioneer axons lose directed growth after selective killing of guidepost cells

Nature (London)

Guidance of peripheral pioneer neurons in the grasshopper: Adhesive hierarchy of epithelial and neuronal surfaces

Nature (London)

Studies on cell migration and axon guidance in the developing distal auditor system of the mouse

J. Comp. Neurol

Axonal navigation

BioScience

Cercal sensory development following laser microlesions of embryonic apical cells in Acheta domesticus

J. Neurosci

Characterization of the turning response of dorsal root neurites toward nerve growth factor

J. Cell Biol

A series of normal stages in the development of the chick embryo

J. Morphol

Peripheral pathways are pioneered by an array of central and peripheral neurones in grasshopper embryos

Nature (London)

Early development of the circumferential axonal pathway in mouse and chick spinal cord

J. Comp. Neurol

Development of the Circumferential Axonal Pathway

Development of circumferential axons in chick embryos: The first spinal cord axons

Soc. Neurosci. Abstr

Full paper
Growth pattern of pioneering chick spinal cord axons☆,☆☆