Development of Arterial and Venous System S-2 CVSM 70
Learning Objectives
By the end of this lecture, the students should be able to understand:
•The relation of Pharyngeal Arches and Aortic Arches
•The fate and formation of aortic arches
•Formation of Brachiocephalic Trunk, Common Carotid and left Subclavian arteries
•The Veins of Embryo
•Development and Fate of Umbilical, Vitelline and Cardinal Veins
LECTURE OUTLINES
•Arterio-Venous System
•Origin of Arterial System
•Aortic arches
•Right and Left Dorsal Aortae
•Aortic Arches
•During the development of Head and Neck, each pharyngeal arch receives its own artery
•Six pairs of arteries called aortic arches course through the pharyngeal arches
•Aortic arches arise from the aortic sac, the most distal part of the truncus arteriosus
•Aortic arches are embedded in mesenchyme of the pharyngeal arches and terminate in the right and left Dorsal Aortae
•Aortic Arches
•The pharyngeal arches and their vessels appear in a cranial to caudal sequence
•Aortic arches are numbered I, II, III, IV, and VI
•The fifth arch either never forms or forms incompletely and then regresses
•During further development, this arterial pattern becomes modified, and some vessels regress completely
•First and Second Arch
•By day 27, most of the first aortic arch has disappeared except a small portion persists to form the maxillary artery
•The second aortic arch soon disappears except a small portion giving rise to hyoid and stapedial arteries
•Third Aortic Arch
•The third aortic arch forms the common carotid artery and the first part of the internal carotid artery
•The remainder of the internal carotid is formed by the cranial portion of the dorsal aorta
•The external carotid artery is a sprout of the third aortic arch
•Fourth Aortic Arch
•The fourth aortic arch persists on both sides, but its ultimate fate is different on the right and left sides
•On the left, it forms part of the arch of the aorta, between the left common carotid and the left subclavian arteries
•On the right, it forms the most proximal segment of the right subclavian artery
• The distal part of right subclavian artery is formed by a portion of the right dorsal aorta and the seventh intersegmental artery.
•Fifth Aortic Arch
•The fifth aortic arch either never forms or forms incompletely and then regresses.
•Sixth Aortic Arch
•The sixth aortic arch is also known as the pulmonary arch
•On the right side, the proximal part becomes the proximal segment of the right pulmonary artery
•The distal portion of Sixth arch on the right side loses its connection with the dorsal aorta and disappears
•On the left, the distal part persists during intrauterine life as the ductus arteriosus.
•Fate of Aortic Arches
•The Dorsal Aorta
•The dorsal aorta between the entrance of the third and fourth arches, known as the carotid duct, is obliterated
•The right dorsal aorta disappears between the origin of the seventh intersegmental artery and the junction with the left dorsal aorta.
•Fate of Dorsal Aorta
•Vitelline and Umbilical arteries
•Arteries supplying yolk sac (number of paired arteries) – vitelline arteries
•They develop in vascular supply of gut – celiac, superior mesenteric, and inferior mesenteric artery
•Umbilical arteries – paired branches of dorsal aorta – to placenta (allantois) in embryonic stalk or later in umbilical cord
•It persist as internal iliac and superior vesical arteries (medial umbilical ligaments)
•Development of Venous System
Three Pairs of Veins are present in embryo:
•Vitelline veins
•Umbilical veins
•Common cardinals veins
•The Veins of the Embryo
•Common Cardinal Veins collect the deoxygenated blood from the body wall
•Each common cardinal vein consists of
–Anterior common cardinal vein
–posterior common cardinal vein
•Umbilical Veins carrying the oxygenated blood from the Placenta
• Vitelline veins bring the deoxygenated blood from the Yolk Sac & gut
•The Veins of the Embryo
•The Veins of the Embryo
•Umbilical Veins
•During the early development of embryo, there are two umbilical veins right and left
•The umbilical veins bring the nutrient- and oxygen-rich blood from the placental villi via the umbilical cord to the embryo
•Left umbilical vein persist through out fetal life and degenerate after the birth of baby
•Right umbilical vein becomes obliterated during the 2nd month
•Fate of Umbilical Veins
•Initially pass along liver, then enter liver participating on sinusoids formation
•Proximal part of both and right left umbilical vein disappear
•Peripheral part of left umbilical vein - in umbilical cord
•Anastomosis with vena cava (right hepatocardial duct) – ductus venosus
•After birth- ligamentum teres hepatis (from artery) and ligamentum venosum (from duct)
•Ductus Venosus
•A large venous shunt, the Ductus Venosus develops within the liver and connects the umbilical vein with inferior vena cava
•The ductus venosus forms a bypass through the liver so that most of the blood directly transported from the placenta to the heart without passing through the capillaries of liver
•Left umbilical vein anastomoses with the ductus venosus.
•Vitelline Veins
•Vitelline veins form plexus surrounding duodenum – pass septum transversum - sinusoids in liver
•The vitelline veins drain into sinus venosus
•Reduction of left sinus horn – blood flow enter right side of heart – right hepatocardiac channel – hepatocardiac portion of the inferior vena cava
•Fate of Vitelline Veins
•Network around duodenum – portal vein
•Left vitelline vein except for hepatic part disappears
•Right viteline vein – superior mesenteric vein
•Formation of Hepatic & Portal Veins
•The hepatic veins form from the remains of the Right vitelline vein in the region of developing liver
•The Portal vein develops from an anastomostic network of vitelline veins around the duodenum
•Common Cardinal Veins
•There are two common cardinal veins right & left
•Each common cardinal vein divided into Anterior cardinal vein bring the deoxygenated blood from cranial part of body & Posterior cardinal vein collects the blood from the caudal part of body
•Ultimately the two common cardinal veins drain into respective horn of sinus venosus
•Cardinal Veins
•Cardinal Veins
•During the eight week of development the anterior cardinal veins are connected to each other by means of an oblique anastomosing channel, that shunts the blood from left to right anterior cardinal vein
•This anastomosing channel become the left Brachiocephalic Vein when the caudal part of left anterior cardinal vein degenerate.
•Subcardinal Veins
•The subcardinal and supracardinal veins are gradually replace and supplement the posterior cardinal vein
•The subcardinal vein lies infront of gut
•The subcardinal veins appear first and form the left renal vein, the suprarenal vein, the gonadal (testicular or ovarian) veins and a segment of inferior vena cava.
•Supracardinal Veins
•The supracardinal veins are disrupted in the region of kidneys behind the gut
•Cranial to this region, they united by an anastomosis that form the Azygos and the hepatic veins
•Caudal to the kidneys the left suprarenal vein degenerates but the Right supracardinal become the part of inferior vena cava
•The IVC is formed due to shunt of the blood from left right site of caudal part of embryo
•Superior Vena Cava
•The superior vena cava is formed from the Right anterior cardinal vein and right common cardinal vein
•Superior Vena Cava receives blood from two brachiocephalic Veins
•Each Brachiocephalic Vein is formed by union of internal jugular vein and subclavian vein
•The adult derivatives of the posterior cardinal veins are the root of azygos veins and common iliac veins
•Development of Inferior Vena Cava
The development of inferior vena cava consists four segments;
•Hepatic Segment, derived from the hepatic vein (proximal part of the right vitelline vein) and hepatic sinusoids
•Prerenal segment is derived from the right subcardinal vein
•Renal Segment is derived from the subcardinal- supracardinal anastomosis
•Postrenal Segment is from right supracardinal vein