What are the pharyngeal pouches?

• A. Out pockets of the pharynx on the inside of the embryo.
• B. Grooves on the outside of the embryo.
• C. Membranes where the pouches meet the clefts.
• D. Arches on the outside of the embryo.

Answer: (A)

The pharyngeal pouches are internal endodermal outpocketings of the pharynx that extend inward from the foregut, forming internal compartments within the developing pharynx. They sit on the inside of the embryo, opposite the pharyngeal arches that are on the outside. This interior location distinguishes them from the grooves (clefts) on the outside and from the arches themselves. The pouches guide the formation of several internal structures, such as parts of the middle ear and certain glands, as development proceeds.