Neural - Spinal Cord Development

Introduction

Neural groove closing to neural tube, early week 4
(Stage 10)

Neural development is one of the earliest systems to begin and the last to be completed after birth. This development generates the most complex structure within the embryo and the long time period of development means in utero insult during pregnancy may have consequences to development of the nervous system.

The early central nervous system begins as a simple neural plate that folds to form a groove then tube, open initially at each end. Failure of these opening to close contributes a major class of neural abnormalities (neural tube defects).

Within the neural tube stem cells generate the 2 major classes of cells that make the majority of the nervous system : neurons and glia. Both these classes of cells differentiate into many different types generated with highly specialized functions and shapes. This section covers the establishment of neural populations, the inductive influences of surrounding tissues and the sequential generation of neurons establishing the layered structure seen in the brain and spinal cord.

Neural development beginnings quite early, therefore also look at notes covering Week 3- neural tube and Week 4-early nervous system.
Development of the neural crest and sensory systems (hearing/vision/smell) are only introduced in these notes and are covered in other notes sections.

Some Recent Findings

Motor neuron position and topographic order imposed by β- and γ-catenin activities^[1] "Neurons typically settle at positions that match the location of their synaptic targets, creating topographic maps. In the spinal cord, the organization of motor neurons into discrete clusters is linked to the location of their muscle targets, establishing a topographic map of punctate design. To define the significance of motor pool organization for neuromuscular map formation, we assessed the role of cadherin-catenin signaling in motor neuron positioning and limb muscle innervation. We find that joint inactivation of β- and γ-catenin scrambles motor neuron settling position in the spinal cord but fails to erode the predictive link between motor neuron transcriptional identity and muscle target. Inactivation of N-cadherin perturbs pool positioning in similar ways, albeit with reduced penetrance. These findings reveal that cadherin-catenin signaling directs motor pool patterning and imposes topographic order on an underlying identity-based neural map."
Dynamic imaging of mammalian neural tube closure^[2]

Development Overview

Neuralation begins at the trilaminar embryo with formation of the notochord and somites, both of which underly the ectoderm and do not contribute to the nervous system, but are involved with patterning its initial formation. The central portion of the ectoderm then forms the neural plate that folds to form the neural tube, that will eventually form the entire central nervous system.

Early developmental sequence: Epiblast - Ectoderm - Neural Plate - Neural groove and Neural Crest - Neural Tube and Neural Crest

**Neural Tube Development**
Neural Tube	Primary Vesicles	Secondary Vesicles	Adult Structures
week 3	week 4	week 5	adult
neural plate neural groove neural tube Brain	prosencephalon (forebrain)	telencephalon	Rhinencephalon, Amygdala, hippocampus, cerebrum (cortex), hypothalamus‎, pituitary \| Basal Ganglia, lateral ventricles
	prosencephalon (forebrain)	diencephalon	epithalamus, thalamus, Subthalamus, pineal, posterior commissure, pretectum, third ventricle
	mesencephalon (midbrain)	mesencephalon	tectum, Cerebral peduncle, cerebral aqueduct, pons
	rhombencephalon (hindbrain)	metencephalon	cerebellum
	rhombencephalon (hindbrain)	myelencephalon	medulla oblongata, isthmus
spinal cord, pyramidal decussation, central canal

Early Brain Vesicles

Primary Vesicles

Secondary Vesicles

Embryonic Development

Week 8

Vertebra and Spinal cord (Carnegie Stage 22)

Plexus Development

The spinal nerves initially leave the spinal cord at each individual segmental levels. At various levels they then form an intersecting network of nerves, a plexus, from which mixed segmental nerves emerge.

Cervical Plexus

Brachial Plexus

Search PubMed: brachial plexus embryology

Lumbar Plexus

Search PubMed: lumbar plexus embryology

Sacral Plexus

References

↑ <pubmed>22036570</pubmed>
↑ <pubmed>20558153</pubmed>

Reviews

Articles

Books

Bayer S.A and Altman J. The Spinal Cord from Gestational Week 4 to the 4th Postnatal Month CRC Press 2002 Print ISBN: 978-0-8493-1420-9 eBook ISBN: 978-1-4200-4018-0 http://www.crcnetbase.com/doi/book/10.1201/9781420040180

Search PubMed

November 2010 search "Spinal Cord Embryology" All (7631) Review (641) Free Full Text (1562)

Search Pubmed: Spinal Cord Embryology | Spinal Cord Development

Glossary Links

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Cite this page: Hill, M.A. (2024, June 2) Embryology Neural - Spinal Cord Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Neural_-_Spinal_Cord_Development

What Links Here?

[1] <pubmed>22036570</pubmed>

[2] <pubmed>20558153</pubmed>

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