Neural - Diencephalon Development

Notice - Mark Hill

Currently this is only a template page and is being updated (this notice removed when completed).

Introduction

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

Autotaxin controls caudal diencephalon-mesencephalon development in the chick "The diencephalon is the embryonic anlagen of the higher integration centers of the brain. Recent studies have elucidated how the cells in the rostral diencephalon acquire their regional identities. However, the understanding of the mechanisms under which the caudal diencephalon is formed is still limited. Here we focus on the role of Autotaxin (ATX), a lysophospholipid-generating exoenzyme, whose mRNA is detected in the caudal diencephalon. RNA interference against ATX altered the expression pattern of Pax6-regualted genes, Tcf4, Lim1, and En1, implying that ATX is required for the maintenance of the regional identity of the caudal diencephalon and the diencephalon-mesencephalon boundary (DMB). Furthermore, ATX-RNAi inhibited neuroepithelial cell proliferation on both sides of the DMB. We propose a dual role of ATX in chick brain development, in which ATX not only contributes to the formation of caudal diencephalon as a short-range signal, but also regulates the growth of mesencephalon as a long-range signal."

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
		diencephalon	epithalamus, thalamus, Subthalamus, pineal, posterior commissure, pretectum, third ventricle
	mesencephalon (midbrain)	mesencephalon	tectum, Cerebral peduncle, cerebral aqueduct, pons
	rhombencephalon (hindbrain)	metencephalon	cerebellum
		myelencephalon	medulla oblongata, isthmus
spinal cord, pyramidal decussation, central canal

Early Brain Vesicles

Primary Vesicles

Secondary Vesicles

References

Reviews

<pubmed>19206138</pubmed>

Search PubMed

Search Pubmed: Diencephalon Embryology | Diencephalon Development |

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Cite this page: Hill, M.A. (2024, April 26) Embryology Neural - Diencephalon Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Neural_-_Diencephalon_Development

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G