Embryonic nervous system

General Information
Latin	Systema nervosum embryonicum
Greek
TA98
TA2
FMA
Details
System	Nervous system
Artery
Vein
Nerve
Lymphatic drainage
Precursor	Ectoderm
Function
Identifiers
Clinical significance
Notes

The embryonic nervous system is a complex structure that begins to form early in the development of the embryo. It is derived from the ectoderm, one of the three primary germ layers in the early embryo. The development of the nervous system is a critical process that leads to the formation of the central nervous system (CNS) and the peripheral nervous system (PNS).

Developmental Stages

The development of the embryonic nervous system can be divided into several key stages:

Neurulation

Neurulation is the process by which the neural tube is formed. It begins with the formation of the neural plate, a thickened region of the ectoderm. The edges of the neural plate elevate to form the neural folds, which then converge at the midline to create the neural tube. This tube will eventually give rise to the CNS, including the brain and spinal cord.

Neural Crest Formation

The neural crest is a group of cells that forms at the border of the neural tube and the ectoderm. These cells migrate to various parts of the embryo and differentiate into a diverse range of cell types, including neurons of the PNS, glial cells, melanocytes, and components of the craniofacial cartilage and bone.

Vesicle Formation

As the neural tube closes, it begins to form three primary brain vesicles: the prosencephalon (forebrain), mesencephalon (midbrain), and rhombencephalon (hindbrain). These vesicles further differentiate into secondary vesicles, which will develop into specific regions of the brain.

Central Nervous System Development

The CNS is derived from the neural tube and undergoes significant changes during embryonic development.

Brain Development

The brain develops from the anterior portion of the neural tube. The prosencephalon divides into the telencephalon and diencephalon, the mesencephalon remains undivided, and the rhombencephalon divides into the metencephalon and myelencephalon. These regions give rise to major brain structures such as the cerebral hemispheres, thalamus, hypothalamus, cerebellum, and medulla oblongata.

Spinal Cord Development

The spinal cord develops from the caudal portion of the neural tube. It is organized into distinct regions, including the dorsal and ventral horns, which contain sensory and motor neurons, respectively.

Peripheral Nervous System Development

The PNS is primarily derived from the neural crest cells and the neural tube.

Neural Crest Derivatives

Neural crest cells migrate to form the sensory ganglia, autonomic ganglia, and enteric nervous system. They also contribute to the formation of the Schwann cells that myelinate peripheral nerves.

Axon Guidance and Synaptogenesis

The growth of axons and the formation of synapses are crucial for the establishment of functional neural circuits. Axon guidance is directed by a combination of attractive and repulsive cues in the embryonic environment.

Clinical Significance

Abnormalities in the development of the embryonic nervous system can lead to congenital disorders such as spina bifida, anencephaly, and neurocristopathies. Understanding the processes involved in neural development is essential for developing therapeutic strategies for these conditions.

See Also

• Neural tube defects
• Neurogenesis
• Embryogenesis

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