Neural Crest Cells Essay

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Neural crest cells are transient vertebral cell types, which form at the boundary between the neural plate and surface ectoderm. They are multipotent and able to migrate and differentiate into numerous derivatives resulting in them being referred to as the ‘fourth germ layer’. It is thought that the evolution of vertebrates is due to large-scale genome duplications which occurred early in the vertebrate lineage. Research suggests that there were two rounds of genome duplication during early vertebrate evolution. However, there is an alternative research model which suggests that in stem vertebrates there was a single round of duplication, followed by lineage-specific segmental duplications in cyclostomes and jawed vertebrates. Despite …show more content…

There is also evidence to suggest that the fate of neural crest cells depends upon their migratory path in the trunk which is dictated by somites. Cells which migrate early move ventrally and pass through the anterior half sclerotome, form the sensory ganglia. Cells which are more dorsal within the anterior sclerotome form the sensory neurons and glia of the dorsal root ganglia, partly due to signals which come from the neural tube. Alternatively, the neural crest cells which migrate late travel laterally between the somite and the ectoderm, forming melanocytes in amniotes. It is thought that the increased complexity in vertebrate neuroanatomy may stem from interactions between neural crest cells and other cell types. An example of this is the essential role of neural crest cells in the expansion of the head and formation of a ‘true neck’. Neural crest cells are thought to be crucial in multiple stages of cranial mesoderm development and secrete signals which depress myogenesis, consequently allowing the formation of cranial myofibres. Research has suggested that these distinct myogenic regulatory sub-networks arose in early vertebrates. The formation of a ‘true neck’ is a result of the pectoral girdle losing its attachment to the skull, and allowed tetrapods to colonise land as they could now move their head independent of limbs. Despite

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