Fig. 2

Comparative analysis of pharyngeal innervation across the verterbates. Patterns of innervation of the developing pharyngeal arches in different vertebrates at the point at which the full complement of pharyngeal segments have been generated. The embryos were wholemount immunostained with and anti-neurofilament antibody and the either bisected and photographed or photographed whole. a Chick b Mouse c Catshark d Lamprey. The cranial nerves are labelled with roman numerals. V – trigeminal, VII – facial, IX – glossopharyngeal, X – vagus, XII – hypoglossal. The pharyngeal arch are numbered with Arabic numerals. The position of the eye is indicated as is the position of the otic vesicle (OV). It is clear that in all embryos there is distinct innervation of the first arch by the Vth nerves, of the second arch by the VIIth nerve and of the third by the IXth nerve. In all embryos the XIIth nerve skirts the caudal edge of the pharynx. It is also apparent that there are a variable number of branches of the Xth nerve innervating the variable number of posterior segments