Figure 42 Fig.
Branchial arches develop late in embryogenesis.
By convention, branchial arch 1 is the same as pharyngeal arch 3 and contains ceratobranchial cartilage 1 and aortic arch 3. A deeper plane of focus reveals a gradient of cartilage development in branchial arches 1-3. In the next arch, ceratobranchial 2 is less differentiated, and in branchial arch 3, to the right, the ceratobranchial is represented by only a row of precartilaginous mesenchymal cells. Neither will the fifth branchial arch bear gills.