A newborn with DiGeorge syndrome has aplasia of the thymus and parathyroid glands. These structures are derived from which pharyngeal pouches?

• A 1st and 2nd pharyngeal pouches
• B 2nd and 3rd pharyngeal pouches
• C 3rd and 4th pharyngeal pouches ✓
• D 4th and 5th pharyngeal pouches

Explanation

The thymus develops from the ventral portion of the 3rd pharyngeal pouch bilaterally. The inferior parathyroid glands (parathyroid III) arise from the dorsal 3rd pouch. The superior parathyroid glands (parathyroid IV) arise from the 4th pharyngeal pouch. DiGeorge syndrome (22q11.2 deletion) causes failure of neural crest cell migration into the 3rd and 4th pouches, leading to thymic aplasia (T-cell immunodeficiency) and hypoparathyroidism. The 1st pouch forms the middle ear and Eustachian tube.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.