Neural - Thalamus Development

Embryology - 18 Apr 2024 Expand to Translate
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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

Wnt3 and Wnt3a are required for induction of the mid-diencephalic organizer in the caudal forebrain^[1] "The thalamus is located in the caudal diencephalon and is the central relay station between the sense organs and higher brain areas. The mid-diencephalic organizer (MDO) orchestrates the development of the thalamus by releasing secreted signaling molecules such as Shh. Here we show that canonical Wnt signaling in the caudal forebrain is required for the formation of the Shh-secreting MD organizer in zebrafish. "
Dynamic imaging of mammalian neural tube closure^[2]

More recent papers
This table allows an automated computer search of the external PubMed database using the listed "Search term" text link. This search now requires a manual link as the original PubMed extension has been disabled. The displayed list of references do not reflect any editorial selection of material based on content or relevance. References also appear on this list based upon the date of the actual page viewing. References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability. More? References \| Discussion Page \| Journal Searches \| 2019 References \| 2020 References Search term: Thalamus Embryology <pubmed limit=5>Thalamus Embryology</pubmed>

Fetal Thalamus

Brain lateral view 13, 15, and 19 weeks the developing thalamus is shown in yellow.^[3]

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