Medicine and Health related Information

These are mesodermal bars of arches which develop in the region of the pharynx. Since in lower animals they form the respiratory organs they are called as BRONCHIAL or GILL ARCHES. Initially there are six pair of arches, later the 5th pair disappears.

Each arch has an outer ectodermal covering, inner endodermal and in the middle mesoderm. Each arch has its own nerve called the post-trematic nerve and a branch from next arch called pretrematic nerve and its own artery.