has part has part has_part characteristic of has modifier dilated vasculature abnormal aortic sac morphology dilated aortic sac aortic sac dilation dilated aortic sacs MPheno.ontology abnormally stretched or widened aperture of the luminal space of the endothelial lined dilation that is located at the arterial pole of the heart just above (distal to) the truncus arteriosus in mammalian embryos; it is the primordial vascular channel from which the aortic arches (and eventually the dorsal aortae) arise; the aortic sac is homologous to the ventral aorta of gill-bearing vertebrates csmith MP:0012511 2014-01-01T13:22:33Z abnormal dilated aortic sac