This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
[{'content': 'Nerve element of brachial arch are developed from \nSelect and explain. \nA. Ectoderm, B. Neural crest cells, C. Endoderm, D. Mesoderm', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref. Gray’s anatomy.\xa0 41st edition. Page. 449.\nTopic, Subtopic – Brachial arch, embryology\nBranchial or pharyngeal arches are masses of mesoderm covered by ectoderm and lined by endoderm. Within these masses, muscular and skeletal components develop, as well as aortic arches and nerve networks. The arches are separated by grooves, visible on the surface of the embryo as pharyngeal clefts and in the interior as the pharyngeal pouches\n\nIn the human embryo, the arches are first seen during the 4th week of development.\nThey appear as a series of outpouchings of mesoderm on both sides of developing pharynx.\n\nThe neural crest are bilaterally paired strips of cells arising in the ectoderm at the margins of the neural tube. These cells migrate to many different locations and differentiate into many cell types within the embryo.', 'role': 'assistant'}]