system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 55-year-old man comes to the physician for evaluation prior to parathyroidectomy. A Tc99m-sestamibi scan shows two spots of increased uptake in the superior mediastinum. These spots represent structures that are most likely derived from which of the following embryological precursors?
assistant
3rd branchial pouch