From the Research
The inferior parathyroid gland originates from the third pharyngeal pouch, making option (c) the correct answer. During embryonic development, the third pharyngeal pouch gives rise to both the inferior parathyroid glands and the thymus, as described in a study published in the journal Development (Cambridge, England) 1. The inferior parathyroid glands develop from the dorsal portion of the third pouch, while the thymus develops from the ventral portion. As development progresses, the inferior parathyroid glands migrate caudally along with the thymus but ultimately separate and come to rest at the lower poles of the thyroid gland. In contrast, the superior parathyroid glands originate from the fourth pharyngeal pouch and undergo less migration, typically residing at the upper poles of the thyroid gland, as noted in a study published in the journal Annales de chirurgie 2. This embryological origin explains the typical anatomical position of the inferior parathyroid glands and is important for understanding potential ectopic locations during surgery. Some studies have investigated the development and patterning of the third pharyngeal pouch into thymus and parathyroid glands, highlighting the role of genes such as Six and Eya1 in this process 3. However, the most relevant information for determining the origin of the inferior parathyroid gland comes from studies that specifically address the embryological development of the parathyroid glands, such as the one published in Development (Cambridge, England) 1. Other studies, such as those published in The Cochrane database of systematic reviews 4 and Annali italiani di chirurgia 5, focus on post-thyroidectomy hypoparathyroidism and do not provide direct information on the embryological origin of the inferior parathyroid gland. Therefore, based on the most relevant and recent evidence, the inferior parathyroid gland originates from the third pharyngeal pouch. Key points to consider include:
- The third pharyngeal pouch gives rise to both the inferior parathyroid glands and the thymus
- The inferior parathyroid glands develop from the dorsal portion of the third pouch
- The superior parathyroid glands originate from the fourth pharyngeal pouch
- Understanding the embryological origin of the parathyroid glands is important for understanding potential ectopic locations during surgery.