Pharyngeal Apparatus 1 •Pharyngeal arches are rod-like thickenings of mesoderm present in the wall of the foregut. •The ventral ends of the arches of the right and left sides meet in the middle line in the floor of the pharynx. •In the interval between any two arches, the endoderm (lining the pharynx) is pushed outwards to form a series of pouches - endodermal, or pharyngeal, pouches. •They are evident in the head and neck region by 4th week •Resemble fish gills (branchia) thus their earlier name .Branchial apparatus - derived from the Greek word branchia or gill •They are derived from neural crest cells