EMBRYOLOGY ASS 3

• Patent ductus arteriosus produces abnormal sounds called murmurs.
• Aspirin facilitates closure of the ductus arteriosus.
• Internal iliac arteries are distal branches of umbilical arteries.
• Closure of the ductus arteriosus is delayed if the newborn is hypoxic or if prostaglandin E is administered.
• Malformation of the aortic arch is characterized by failure of the ductus arteriosus to close after birth.
• From it arise the common carotid and right subclavian arteries.
• The dorsal aorta gives off three major branches: Dorsal intersegmental arteries, Lateral thoracic branches, and Ventral aortic branches.
• Dorsal intersegmental arteries arise bilaterally between somites and group according to the region of vertebral column where they are located as: Occipital dorsal intersegmental arteries, Cervical dorsal intersegmental arteries, Thoracic dorsal intersegmental arteries, and Abdominal dorsal intersegmental arteries.
• Ventral aortic branches initially pair but the left ventral arteries eventually degenerate and the right ventral arteries give rise to the following adult arteries: Cranial mesenteric artery, Bronchoesophageal artery, Celiac artery, Caudal mesenteric artery, Common internal iliac arteries, Proximal internal iliac arteries, Popliteal arteries, Tibial arteries.
• Lateral thoracic branches include Phrenicoabdominal arteries, Renal arteries, Ovarian/testicular arteries, and Deep circumflex iliac arteries.
• In the horse, cow and pig the common carotids fuse, forming a bicarotid trunk.
• Transformation of the aortic arches occurs simultaneously with the partitioning of the heart into four chambers, which allows for separate pulmonary and systemic circulation.
• The shift is greatest in the horse and ruminants in which the left subclavian shifts cranially onto the brachiocephalic trunk.
• Rather than being stretched during the elongation of the neck and thorax, there is cranial shift at which this artery branches from the left dorsal aortic root.
• The brachiocephalic trunk develops from the remodeling of the aortic sac and the proximal part of the left and right 3rd and 4th aortic arches.
• Critical to this separation is the formation of a partition, the aorticopulmonary septum, in the aortic sac between the origin of the 4th and 6th arches.
• Later this partition fuses with a septum that bisects the truncus arteriosus and together these segregate pulmonary from systemic cardiac outflow channels.
• This transformation results in it being the first extracardiac branch off of the aorta.
• The proximal part of the right subclavian artery, which was formerly the right 4th aortic arch, also shifts cranially and usually becomes a branch of the brachiocephalic trunk.
• Deviations from the typical pattern of great vessel branching can also occur among members of the same species.
• The composite vessel on the right side of the embryonic body is the right subclavian artery.
• The right dorsal aortic root degenerates caudal to the origin of
• Initially these small segmental arteries grow dorsally between the somites.
• The 3 rd aortic arches give off extensions called the external carotid arteries to the facial region.
• Later the distal part of the right 6 th aortic arch degenerates between the pulmonary artery and the right dorsal aortic root.
• The 3 rd aortic arches are the major arterial channels from the heart to the head, and the 4 th aortic arches are the principal channels to the trunk.
• On both sides of the embryo this remaining intersegmental artery forms a ventral branch that enters the base of the thoracic or anterior limb bud.
• The paired dorsal aortae extending from the 4 th aortic arches to the single, median aorta are called the dorsal aortic roots.
• The right dorsal aortic root degenerates caudal to the origin of the 7 th cervical intersegmental artery.
• The 6 th aortic arches give off one branch each called the pulmonary artery to the lung.
• Later each segmental artery forms a dorsal intersomitic branch and a ventral intersomitic branch.
• As a result, there is no direct connection between the right aortic arch and the dorsal aorta serving the trunk region.
• However, in the later development they will appear quite differently.
• The right and left subclavian arteries initially form symmetrically.
• The dorsal intersomitic branches of adjacent cervical intersegmental arteries anastomose to form a longitudinal vessel called the vertebral artery on each side of the embryo.
• This ventral branch will become the distal part of the subclavian artery.
• After the formation of the vertebral artery the original cervical intersegmental arteries degenerate except the 7 th intersegmental artery.
• The dorsal aortic roots give off a series of cervical dorsal intersegmental arteries.
• The distal part of the left 6 th aortic arch between the left pulmonary artery and left dorsal aortic root persists and becomes the ductus arteriosus.
• Hematopoiesis is the process of blood tissue formation, including erythropoiesis, red blood cell formation, which continues throughout the life of the animal with new blood cells continually being produced from stem cells.