CARDIAC NEURAL CREST
The neural crest is a
transient population of cells that form from the dorsal ectoderm at the time of neural tube closure (Fig. 1.5). The neural crest population arises through a
series of inductive interactions with surrounding tissues around the fourth
week of development.
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| FIG 1.5 Nervous tissue of embryo at 24 days and 4 weeks. |
Once formed, the cells undergo an
epithelial-to-mesenchymal transition, migrating ventrally and laterally to
contribute to a wide array of tissue types, including the epinephrine-producing
cells of the adrenal gland, the parasympathetic neurons, cartilage, bone,
connective tissue, and pigment cells. The neural crests themselves are
multipotential at the time of their
formation; their ultimate fate is a reflection of their relative position along
the anterior-to-posterior axis of the embryo. In the cranial portions of the
embryo, classic fate mapping studies showed that a subpopulation of neural
crest cells enter the arterial pole or the venous pole of the heart to give
rise to all of the parasympathetic innervation of the heart, the smooth muscle
layer of the great vessels, and portions of the outflow tract. This population
is termed the cardiac neural crest. Ablation studies in chicks and genetic
studies in mammals demonstrated not only that the cardiac neural crest cells
contribute to these regions of the heart but also that they are also essential
for the proper formation of each of
these structures.
