neural crest

The neural crest is a population of pluripotent, migratory cells that form during vertebrate development. This population originates from the edges of the neural tube and the epidermis of the embryo. These cells migrate, colonizing a large part of the embryo shortly after the end of neurulation. The neural crest is sometimes referred to as the fourth germ layer because of its great importance in development.

Neural crest cells are very important and their ultimate goal will depend on where they migrate:

  • Neurons of the sensory, spinal and cranial nerve ganglia V, VII, IX and X.
  • ANS ganglia neurons.
  • Nerves (except somatic and preganglionic autonomic motor fibers).
  • Schwann cells and satellite cells of sensory and autonomic ganglia.
  • The pia mater and arachnoid mater of the telencephalon, diencephalon, and upper half of the midbrain.
  • the melanocytes.
  • The odontoblasts.
  • Connective tissue and craniofacial bones.
  • Chromaffin cells of the adrenal medulla.
  • Prafollicular cells and thyroid tissue.
  • Connective tissue of the thymus and parathyroid.
  • Aortic pulmonary septum and semilunar valves of the heart.
  • connective tissue of the salivary glands.
  • ciliary muscle.
  • Anterior epithelium and corneal substantia propria.
  • Part of the connective tissue of the lacrimal glands.

For proper migration and formation of neural crest derivatives, some genetic factors are needed, such as BMP and Wnt6, which, when found at high levels in the presumptive epidermis, start the process.

Based on its arrangement throughout the embryo, the neural crest can be divided into four major, overlapping domains:

  • Cranial or cephalic neural crest: Differentiates into cartilage, bone, cranial neurons, glia, and connective tissue of the face.
  • Neural stem of the trunk: the poorly migrating cells are responsible for forming ganglia that form sensory neurons, while the ventrally migrating cells form mainly sympathetic ganglia and the adrenal medulla. The cells in this domain then transform into melanocytes that synthesize pigment.
  • Vague and sacral neural crest: generates parasympathetic ganglia of the intestine.
  • Cardiac neural crest: These cells can generate melanocytes, neurons, cartilage, and connective tissue. Originates all the connective-muscular tissue of the arterial walls as they are generated from the heart.