Question #183
Which of the following structures form from the 4th pharyngeal pouch?
There are 4 pharyngeal pouches as the endoderm invaginates between adjacent pharyngeal arches:
- 1st pouch: middle ear cavity and eustachian tube
- 2nd pouch: palatine tonsils
- 3rd pouch: inferior parathyroid glands and thymus
- 4th pouch: superior parathyroid glands and ultimobranchial body.
The ultimobranchial body is sometimes classified as the 5th pouch. It contains neural crest cells which contribute to the parafollicular c-cells of the thyroid gland.
