What is Neural Crest?

Information about Neural Crest

Two stages in the development of the neural crest in the human embryo.
subject #184 736
Carnegie stage9
Days24
Precursorectoderm
MeSH Neural+Crest
The neural crest, a transient component of the ectoderm, is located in between the neural tube and the epidermis (or the free margins of the neural folds) of an embryo during neural tube formation. Neural crest cells quickly migrate during or shortly after neurulation, an embryological event marked by neural tube closure.

It has been referred to as the fourth germ layer, due to its great importance. The neural crest can give rise to neurons and glia of the peripheral nervous system (PNS); some skeletal elements, tendons and smooth muscle; chondrocytes, osteocytes, melanocytes, chromaffin cells, and supporting cells and hormone producing cells in certain organs.

Clinical significance

Diseases due to defects in the neural crest induction, formation or migration are referred to as neurocristopathies, and genes that cause some of these like piebaldism and Hirschprung's disease have been cloned in mice models.

History and Nomenclature

In 1868 His described Neural Crest as "zwischenstrang"- a strip of cells lying between the dorsal ectoderm and the neural tube.[1]

From this time till almost 1950s most of the work on this structure was done on amphibian embryos, eg a 1950 comprehensive review in a monograph by the Swedish embryologist Sven Hörstadius.[2] Newth (who also studied it in fishes)[3] in 1951 described it as such by "a remarkable embryonic structure" and till another decade its origin still remained an enigma!

In 1960s with the invent of cell labeling with tritiated thymidine by Chibon[4] and Weston[5] gave rise to a major breakthrough in this field through amphibian and avian studies. But this was a transient method of cell labeling and the field had to wait till the chick-quail transfer studies were devised for a definitive confirmation of those results. These extensive works in 1970s was reviewed extensively in "the Neural Crest" by Nicole Le Douarin first published in 1982 (and second ed in 1999).[6]

The nomenclature of these cells derives from amphibian and avian studies which demonstrate migration from the neural crest which forms on the rostral region of the neurulating ectoderm in the trilaminar disc. In humans, the cells actually migrate from the lateral margins of the neural tube however the use of 'crest cells' in this regard is retained.

Induction

Cells fated to become neural crest tissue are induced by BMP, Wnt and FGF signaling to express the proteins Fox3D, RhoB and Slug, and to lose expression of E-cadherin.
  • RhoB is likely to signal cytoskeletal changes required for migration. [7]
  • Slug is a repressor[8] that leads to an activation of factors that dissociate tight junctions.

Categories

There are several main categories of neural crest based upon function:[9]

Cranial neural crest

  • The cranial neural crest arises in the anterior and populates the face and the pharyngeal arches giving rise to bones, cartilage, nerves and connective tissue.
Other Migration Locations:
*Into the pharyngeal arches and play an inductive in thymus development.
*Into the pharyngeal arches and form the parafollicular cell or ultimobranchial bodies of the thyroid gland.
*Into the pharyngeal arches and play an inductive role in parathyroid gland development.
*Facial ectomesenchyme of the pharyngeal arches forming skeletal muscle, bone, and cartilage in the face.
*Odontoblasts (dentin-producing cells) of the teeth.
*Into the optic vesicle and the developing eye and contributes to many anterior eye elements such the cornea, sclera, and ciliary muscle. It also contributes to the attaching skeletal muscles of the eye.
*Into the otic placode and participates in the inner ear development.
*Sensory ganglia of the fifth, seventh, ninth and tenth cranial nerves.

Vagal and sacral neural crest

  • The vagal and sacral neural crest arises in the neck and tail and populates the gut, forming the parasympathetic neurons that regulates peristalsis and control blood vessel dilation.
Other Migration Locations:
*Walls of the viscera to become enteric ganglia.

Trunk neural crest

  • The trunk neural crest lies between the vagal and sacral neural crest and gives rise to two groups of cells. One group migrates dorsolateral and populates the skin, forming pigment cells and the other migrates ventrolateral through the anterior sclerotome to become the epinephrine-producing cells of the adrenal gland and the neurons of the sympathetic nervous system. Some cells remain in the sclerotome to form the dorsal root ganglia
Other Migration Locations:
*Proximal to the spinal cord and line up symmetrically to form the dorsal root ganglia.
*Into the skin to form melanocytes and Merkel cells.
*Chromaffin cells of the adrenal medulla.
*Near the vertebral column and become sympathetic chain ganglia.

Cardiac neural crest

  • The cardiac neural crest overlaps the vagal neural crest and migrates to populate the pharyngeal arches 3, 4 and 6 (producing structures in the head) and to the heart, forming connective tissue that separates the great vessels of the heart.
Other Migration Locations:
*Into the pharyngeal arches and Truncus arteriosus (embryology), forming the aorticopulmonary septum and the smooth muscle of great arteries.
*Anterior of the aorta to become the four pre-aortic ganglia (celiac ganglion, superior mesenteric ganglion, inferior mesenteric ganglion and aortical renal ganglia)

Migration

Neural crest cells require extracellular matrix to migrate through interactions between integrins and fibronectin and laminin. Migration is directed by inhibitory and attractive signals from cells. Ephrin is an inhibitory ligand in posterior sclerotome that affects ventral pathway trunk neural crest cells and causes them to migrate through the anterior sclerotome instead. Thrombospondin promotes migration through the anterior sclerotome. Another signal, stem cell factor is involved in specifying the destination of migration. If expressed in the wrong locations, pigment cells migrate to that site and proliferate there.

Plasticity

Neural crest cells show varying degrees of plasticity. Some trunk neural crest cells are pluripotent. Cranial neural crest cells can give rise to trunk neural crest cells if transplanted. However, heart neural crest cells are committed before migration. Individual neural crest cells can take on a new fate, however groups of neural crest cells cannot.

See also

References

1. ^ Neural Crest Introduction. Retrieved on 2007-09-18.
2. ^ Neural Crest and the Origins of Craniofacial Pattern. Retrieved on 2007-09-18.
3. ^ Newth DR (1950). "Fate of the neural crest in lampreys". Nature 165 (4190): 284. PMID 15405801. 
4. ^ Chibon P (1967). "[Nuclear labelling by tritiated thymidine of neural crest derivatives in the amphibian Urodele Pleurodeles waltlii Michah]" (in French). Journal of embryology and experimental morphology 18 (3): 343–58. PMID 5590717. 
5. ^ Weston JA (1963). "A radioautographic analysis of the migration and localization of trunk neural crest cells in the chick". Dev. Biol. 6: 279–310. PMID 14000137. 
6. ^ Kalcheim, Chaya; Le Douarin, N. (1999). The neural crest. Cambridge, UK: Cambridge University Press. ISBN 0-521-62010-4. 
7. ^ Liu JP, Jessell TM (1998). "A role for rhoB in the delamination of neural crest cells from the dorsal neural tube". Development 125 (24): 5055–67. PMID 9811589. 
8. ^ Vernon AE, LaBonne C (2006). "Slug stability is dynamically regulated during neural crest development by the F-box protein Ppa". Development 133 (17): 3359–70. DOI:10.1242/dev.02504. PMID 16887825. 
9. ^ Neural Crest Migration. Retrieved on 2007-09-18.

External links

 •  • [ e]
Stages of Development in Developmental Biology
Early Embryonic DevelopmentFertilization - Egg activation - Cleavage - Gastrulation - Regional specification
Late Embryonic DevelopmentEctoderm: Neurulation - Neural crest - Eye development - Cutaneous structure development Mesoderm: Heart development Other: Limb development - Germ line development - Programmed cell death - Stem cells
Post Embryonic DevelopmentMetamorphosis - Regeneration - Aging
 •  • [ e]
Prenatal development/Mammalian development of nervous system
General neural development/NeurulationNeurula - Notochord - Neural folds - Neuroectoderm - Neural plate - Neural groove
Neural crest - Neural tube (Neuromere/Rhombomere, Cephalic flexure)
Eye developmentOptic vesicles - Optic stalk - Optic cup
Auditory developmentAuditory vesicle - Auditory pit
This article or section is in need of attention from an expert on the subject.
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In embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo.

The stages are delineated through the development of structures, not by size or the number of days of development, and so the
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Embryology is the study of the development of an embryo. An embryo is defined as any vertebrate in a stage before birth or hatching. Embryology refers to the development of the egg cell (zygote) after fertilization and the differentiation of cells into tissues and organs.
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The ectoderm is the start of a tissue that covers the body surfaces. It emerges first and forms from the outermost of the germ layers.

What forms from it (general)?

  • Nervous system
  • Outer part of integument

What forms from it (vertebrates)?


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Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
..... Read more.
The ectoderm is the start of a tissue that covers the body surfaces. It emerges first and forms from the outermost of the germ layers.

What forms from it (general)?

  • Nervous system
  • Outer part of integument

What forms from it (vertebrates)?


..... Read more.
neural tube is the embryo's precursor to the central nervous system, which comprises the brain and spinal cord. The neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into a
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neural folds; they commence some little distance behind the anterior end of the embryonic disk, where they are continuous with each other, and from there gradually extend backward, one on either side of the anterior end of the primitive streak.
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Neurulation is a part of organogenesis in vertebrate embryos. Steps of neurulation include the formation of the dorsal nerve cord, and the eventual formation of the central nervous system.
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neural tube is the embryo's precursor to the central nervous system, which comprises the brain and spinal cord. The neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into a
..... Read more.
germ layer is a collection of cells, formed during animal embryogenesis. Germ layers are only really pronounced in the vertebrates. However, all animals more complex than sponges (eumetazoans and ) produce two or three primary tissue layers
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The Peripheral nervous system resides or extends outside the "CNS" central nervous system (the brain and spinal cord) to serve the limbs and organs. Unlike the central nervous system, however, the PNS is not protected by bone, leaving it exposed to toxins and mechanical injuries.
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MeSH D016116 Piebaldism is a rare autosomal dominant disorder of melanocyte development. Common characteristics include a congenital white forelock, scattered normal pigmented and hyperpigmented macules and a triangular shaped depigmented patch on the forehead.
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MeSH D006627 Hirschsprung's disease, or congenital aganglionic megacolon, involves an enlargement of the colon, caused by bowel obstruction resulting from an aganglionic section of bowel (the normal enteric nerves are absent) that starts at the anus and progresses
..... Read more.
Sven Hörstadius (1898-1996) was an embryologist known for his work on sea urchin embryos.[1][2]

He was responsible for an increased understanding of the neural crest.[3]

References

1.

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Bone Morphogenetic Proteins (BMPs) are a group of growth factors and cytokines known for their ability to induce the formation of bone and cartilage.

Types

Originally, seven such proteins were discovered.
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Identifiers
Symbol WNT2
Alt. Symbols INT1L1

Entrez 7472
HUGO 12780
OMIM 147870

RefSeq NM_003391
UniProt P09544
Other data

Locus Chr.
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Fibroblast growth factors, or FGFs, are a family of growth factors involved in wound healing and embryonic development. The FGFs are heparin-binding proteins and interactions with cell-surface associated heparan sulfate proteoglycans have been shown to be essential for FGF
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RHOB is a member of the Rho GTP-binding protein family.

See also

  • neural crest


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Stylommatophora

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Subinfraorders, superfamilies, and families
See text
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Slug
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Cadherins are a class of type-1 transmembrane proteins. They play important roles in cell adhesion whereby they ensure cells within tissues are bound together. They are dependent on calcium (Ca2+) ions to function, hence their name.
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thymus is an organ located in the upper anterior portion of the chest cavity just behind the sternum. Hormones produced by this organ stimulate the production of certain infection-fighting cells. It is of central importance in the maturation of T cells.
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Parafollicular cells (also called C cells) are cells in the thyroid which produce and secrete calcitonin.

Embryologically, they are derived from the ultimobranchial body, which itself is a derivative of the fourth pharyngeal pouch.
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The ultimobranchial body or gland is a small organ found in the neck region of many animals.

In humans, the ultimobranchial body is an embryological structure that gives rise to the calcitonin-producing cells—also called parafollicular cells or clear
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For other uses, see Thyroid cartilage.


The thyroid is one of the largest endocrine glands in the body. This gland is found in the neck just below the laryngeal prominence.
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The parathyroid glands are small endocrine glands in the neck, usually located behind the thyroid gland, which produce parathyroid hormone. In rare cases the parathyroid glands are located within the thyroid glands.
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Mesenchyme (also known as embryonic connective tissue) is the mass of tissue that develops mainly from the mesoderm (the middle layer of the trilaminar germ disc) of an embryo. Viscous in consistency, mesenchyme contains collagen bundles and fibroblasts.
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In the development of vertebrate animals, the pharyngeal arches (also called branchial arches or gill arches in fish) develop during the fourth and fifth week in utero
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An odontoblast is a biological cell of neural crest origin that is part of the outer surface of the dental pulp, and whose biological function is dentinogenesis, which is the creation of dentin, the substance under the tooth enamel.
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Dentin (BE: dentine) is a calcified tissue of the body, and along with enamel, cementum, and pulp is one of the four major components of teeth. Usually, it is covered by enamel or cementum and lays over the pulp.
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