DiGeorge syndrome results from failure of development of the 3rd and 4th pharyngeal pouches. Which structure specifically fails to develop, leading to T-cell immunodeficiency?
- A Thymus and inferior parathyroid glands ✓
- B Tonsils and adenoids
- C Parotid gland and submandibular gland
- D Eustachian tube and middle ear cavity
Correct answer: A. Thymus and inferior parathyroid glands
Explanation
The 3rd pharyngeal pouch gives rise to the inferior parathyroid glands and the thymus. The 4th pharyngeal pouch forms the superior parathyroid glands. DiGeorge syndrome (22q11.2 deletion) causes aplasia/hypoplasia of the 3rd and 4th pouches, resulting in absent/hypoplastic thymus (T-cell immunodeficiency) and hypoparathyroidism (hypocalcaemic tetany). The 1st pouch forms the middle ear and Eustachian tube; the 2nd pouch forms the palatine tonsil; the 1st cleft forms the external auditory meatus.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.