1. Neural crest
By :
Sara Abd El Hafiz Mehrez

2. origin
 The neural crest (NC) is ectodermal in origin, They
have an amazing differentiation potential to
generate both ectodermal and mesodermal
derivatives. Also have a migration potential that
involves them in the embryogenesis of many distant
tissues
 Derived from the neural folds on both sides of the
neural groove that runs longitudinally along the axis
of the embryo and deepens progressively to close
the neural tube. Cells located on either side of the
tube are the first elements of the NC that will
subsequently adopt a segmental pattern .

3. Neural crest formation
•Germ cells layers

4. Cell lineages
 Cranial neural crest
migrates dorsolaterally to form the craniofacial
mesenchyme that differentiates into various cranial
ganglia and craniofacial cartilages and bones .
These cells enter the pharyngeal pouches and arches
where they contribute to the thymus, bones of the
middle ear and jaw and the odontoblasts of the
tooth primordia.
 Vagal and sacral neural crest
develop into the ganglia of the enteric nervous
system and the parasympathetic ganglia

5.  Trunk neural crest
Gives rise to two populations of cells. One group of cells
fated to become melanocytes migrates dorsolaterally into the
ectoderm towards the ventral midline. A second group of cells
migrates ventrolaterally through the anterior portion of each
sclerotome. The cells that stay in the sclerotome form the
dorsal root ganglia, whereas those that continue more
ventrally form the sympathetic ganglia, adrenal medulla, and
the nerves surrounding the aorta
 Cardiac neural crest
Develops into melanocytes, cartilage, connective tissue and
neurons of some pharyngeal arches. Also, this domain gives
rise to regions of the heart such as the musculo-connective
tissue of the large arteries, and part of the septum, which
divides the pulmonary circulation from the aorta. The
semilunar valves of the heart are associated with neural crest
cells according to new research

6. Neural Crest derivatives
• Mesectoderm : odontoblasts, dental
papillae, the chondrocranium (nasal capsule,
Meckel's cartilage, scleral ossicles, quadrate,
articular, hyoid and columella), tracheal and
laryngeal cartilage, the dermatocranium
(membranous bones), dorsal fins and the turtle
plastron (lower vertebrates), pericytes and
smooth muscle of branchial arteries and veins,
tendons of ocular and masticatory muscles,
connective tissue of head and neck glands
(pituitary, salivary, lachrymal, thymus, thyroid)
dermis and adipose tissue of calvaria, ventral
neck and face

7. • Endocrine Cells: chromaffin cells of the adrenal
medulla, parafollicular cells of the thyroid, glomus
cells type I/II
• Peripheral nervous system: Sensory neurons and
glia of the dorsal root ganglia, cephalic ganglia
(VII and in part, V, IX, and X), Rohon-Beard
cells, some Merkel cells in the whisker,Satellite
glial cells of all autonomic and sensory ganglia,
Schwann cells of all peripheral nerves
• Melanocytes and iris pigment cells

9. Malformations of NC origin
• Facial clefts, ear malformations, and other
Facial defects
• Branchial fistulae and anomalies of
pharyngeal arch derivatives
• Cardiovascular malformations
• Pigmentary disorders
• Abnormal enteric innervation
• Tumors
• Hemangiomas and vascular malformations

10. Facial clefts, ear malformations,
and otherfacial defects
 The advancement of the embryonal frontonasal bud and
the fusion of its lateral and medial processes give rise to
the nose and upper lip. The maxillary processes fuse
laterally with these structures to shape the upper face.
Below the future mouth, the mandibular processes fuse in
the midline to form the jaw.
 Components of the first and second arches form the
auricle.
 The shaping of the face is therefore patterned under the
influence of the NC.
 The more common malformations of the region, like
preauricular tags, microtia, cleft lip, and cleft palate as
well as other more complex facial anomalies like
CHARGE association, Treacher Collins, or Goldenhar
syndromes are NC-related

12. Branchial fistulae and anomalies of
pharyngeal arch derivatives
 Brachial fistula and cyst due to persistant 2nd
pharyngeal arch which normally regress
 Malformations of the endocrine glands that are derived
from the pharyngeal arches and pouches have the
same origin :
 The paired thymus anlage, which originate from the
third pharyngeal pouch on each side
 The parathyroids, derived from the third (lower glands)
and fourth pharyngeal pouches (upper glands)
 C-cells of the thyroid (derived from the ultimobranchial
body in the fifth pouch)

13. Brachial cyst

14. Cardiovascular malformations
 During the embryonal period the initially tubular heart
folds itself to acquire an S-shape that outlines the final
design of the atria and the ventricles. The outflow tract that
corresponds to the end of the tube will be ultimately
cleaved to form separate aorta and pulmonary arteries. Part
of the cellular material involved in this cleavage of NC
origin .
 TA, DORV, Tetralogy of Fallot (TOF), narrow
outflow pulmonary tract (NOPT), transposition of the great
vessels, perimembranous ventricular septal defect (VSD),
and other heart defects are the result of defective NC
influence on the region .

15. Pigmentary disorders
 Albinism is the result of the absence of this
migration/differentiation congenital nevi .
 Neurocutaneous melanoses with their malignant
potential neurofibromatosis of Von Recklinghausen in
which there are cafe´-au-lait cutaneous spots,
neurofibromas, skeletal deformities and a potential for
several varieties of tumors is also the result of NC
dysfunction .
 Tuberous sclerosis and all the gastrointestinal
polyposes in which there are mucosal or cutaneous
pigmentary spots (Peutz Jeghers, Cowden, Cronkhite-
Canada etc) have oncogenic potential and share their
NC-related origin .

16. neurofibromatosis albinism

17. Abnormal enteric innervation
 Hirschsprung disease related to mutations of the
RET protooncogene
 Neuronal intestinal dysplasia is also of NC
origin and has been studied in animals with mutations
of the gene Ncx/Hox11L.1
 Waardenburg syndrome, there is abnormal
pigmentation of the hair, skin, and irises facial
dysmorphia; neurosensorial deafness; and sometimes
hypo- or aganglionosis that is related to mutations of
SOX10 or Pax3 genes . The same condition is
observed in some animal strains with mutations of
these genes

18. Tumors
 Due to abnormal proliferation of NC cells
.
 Neuroblastoma , Neuroblastoma ,
ganglioneuroma are good examples of the
differentiation potential of these cells
 Peripheral neuroectodermal tumor, known
as Askin tumor when it is located in the
thoracic wall, is probably derived
from the Schwann cells of the
intercostal nerve that are NC-derived

19. Hemangiomas and vascular malformations
 The concept that hemangiomas and vascular
malformations are derived from the NC is
relatively new, but accepted.
 The flat vascular malformations that are
located in the areas corresponding to the
cutaneous innervation of the cranial nerves
may have intracraneal extension (Sturge-
Weber syndrome) and are of this origin .

20. References
[1] Moore KL, Persaud TVN. The developing human. Clinically
oriented embryology. 7th ed. Philadelphia7 Saunders; 2003. p.
560.
[2] Larsen WJ. Human embryology. 2nd ed. New York7
Churchill Livingstone; 1997. p. 512
[3] Johnston MC, Bronsky PT. Animal models for human
craniofacial malformations. J Craniofac Genet Dev Biol
1991;11:277 - 91.
[4] Granstrom G, Kullaa-Mikkonen A. Experimental craniofacial
malformations induced by retinoids and resembling branchial
arch syndromes. Scand J Plast Reconstr Surg Hand Surg
1990;24:3 - 12.