Question

What are neural crest cells? Do you think that they should be considered a fifth germ layer? Why or why not? How do neural crest cells contribute to the formation of the peripheral nervous system in vertebrates? Explain and describe 2 factors that control axonal specificity.

Answer 1

• Neural crest cells are a temporary group of cells unique to vertebrates that arise from the embryonic ectoderm germ layer, and in turn, give rise to a diverse cell lineage - including melanocytes, craniofacial cartilage, and bone smooth muscle, peripheral and enteric neurons, and glia.
• Yes, they should be considered a fifth germ layer.
• Upon reaching their destinations in the periphery, neural crest cells stop migrating, often reaggregate, and contribute to numerous vertebrate structures. They build much of the head skeleton, form all epidermal pigment cells, and most of the peripheral nervous system.