Figure 3.

Stages of outflow septation as reported in quail-chick chimeras. (A) U-shaped condensed mesenchyme of the aorticopulmonary septation complex is continuous with the smooth muscle tunica media of the aortic arch arteries. (B) Septation of the distal and middle portions of the arterial pole by the aorticopulmonary septation complex. The septum forms at the expense of the prongs. (C) Septation of the conus leaves a seam of subendocardial cardiac neural crest cells. (Adapted from Kirby and Hutson, 2010).