Final answer:
The 5th pharyngeal pouch becomes the ultimobranchial bodies, which are part of the thyroid gland contributing to the parafollicular cells that secrete the hormone calcitonin.
Step-by-step explanation:
The 5th pharyngeal pouch is an embryonic structure that gives rise to specific structures within the neck and head. In human development, the derivatives of the 5th pharyngeal pouch include the ultimobranchial bodies, which become part of the thyroid gland, contributing to the parafollicular cells (also known as C cells) that secrete calcitonin, a hormone involved in the regulation of calcium levels in the body.
During the embryonic period, particularly around weeks 4-7, the pharyngeal pouches play critical roles in the formation of the face, neck, and related structures. The 5th pharyngeal pouch is one of several pouches that play a part in this complex developmental process.