Image Based Question – 65233

The most common development of gland marked as “A” in the picture below is from which of the structures?

A. Brachial cyst.

B. Brachial cleft.

C. Brachial pouch.

D. Brachial arch.

Show Answer

Correct Answer » C Explanation

Anc;C. Brachial pouch

The gland marked as “A” in the picture above represents the Parathyroid gland.

• The parathyroid glands develop from the endoderm of the third and fourth pharyngeal pouches (Brachial Pouch). The thymus is also derived from the third pharyngeal pouch.

• The endodermally lined pharyngeal pouches, transient in nature, give rise to important structures. The derivatives of the pharyngeal pouches has a dorsal and a ventral part.

Pouch 1	ventral	Obliterated: no derivative
	dorsal	pharyngotympanic tube and middle ear cavity
Pouch 2	Ventral	palatine tonsil,partially obliterated by endoderm
	dorsal	contributes to pharyngotympanic tube
Pouch 3	Ventral	thymus
	dorsal	inferior parathyroid gland
Pouch 4	ventral	ultimobranchialbodies (C-cells of thyroid gland)
	dorsal	superior parathyroid gland