Neural crest cells: origin and fate
Neural crest cells form at the lateral border of the neural plate (the strip on the embryo's back that becomes nervous tissue), then leave to form many tissues.
Remember
Neural crest cells begin at the lateral border of the neural plate, then leave to form peripheral nerve cells, pigment-making cells (melanocytes) and parts of the heart. The neural tube, the hollow tube that becomes the brain and spinal cord, builds the central nervous system instead.
Memory aid
The crest sits on the edge of the plate, like the crest of a wave.
Picture the top edge of a wave to recall that neural crest cells begin at the border of the neural plate.
A strip on the back of the embryo thickens into the neural plate. The edges of the plate rise as neural folds, which fuse to form the neural tube, the hollow tube that becomes the brain and spinal cord. As the folds fuse, a band of cells at the border of the plate separates from the tube. These are the neural crest cells. The notochord (a rod of mesoderm, one of the embryo's layers, in the midline) sends signals that induce the plate, but it is not the source of these cells.
The neural crest cells then migrate: they detach from the border and go to many parts of the embryo, where they specialise into very diverse cell types. They form nerve cells (neurons) and support cells of the peripheral nervous system, including sensory neurons, as well as the neurons of the gut wall, pigment-making melanocytes, parts of the heart, and much of the cartilage and bone of the face.
The neurons of the cerebral cortex come from the wall of the neural tube. Skeletal muscle and kidney come from mesoderm, and the liver comes from endoderm, the innermost layer, which lines the gut.
Since so many tissues depend on these cells, faulty migration can cause neurocristopathies, which are disorders of neural crest development, such as DiGeorge syndrome and Treacher Collins syndrome. Cardiac neural crest cells help the outflow tract of the heart (which divides into the aorta and the pulmonary trunk), the thymus and the parathyroid glands (which make parathyroid hormone) to develop. In DiGeorge syndrome, they fail to support these structures. A fault can cause a heart defect, recurrent infections and a low blood calcium.
Key facts
- Origin
- the lateral border of the neural plate
- Behaviour
- the cells leave the border and migrate widely through the embryo
- Products
- peripheral nerve cells (including sensory neurons), melanocytes, parts of the heart, and much of the cartilage and bone of the face
- Not neural crest
- the brain and spinal cord come from the neural tube, limb muscle from mesoderm and liver cells from endoderm
- Faults
- neurocristopathies such as DiGeorge syndrome and Treacher Collins syndrome
- DiGeorge link
- cardiac neural crest cells fail to support the outflow tract, thymus and parathyroid glands
Exam traps
- The notochord does not give rise to neural crest cells, because it is a rod of mesoderm in the midline that sends signals inducing the neural plate.
- Skeletal muscle of the limbs does not come from neural crest, because it develops from mesoderm, so a neural crest migration defect leaves limb muscle largely intact.
- Neurons of the cerebral cortex do not come from the neural crest, because they come from the wall of the neural tube, which makes the central nervous system.
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