. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. LEFT LUNG LIGAMENTUM ARTERl DUCTUS ARTERl RIGHT AT RIGHT VENTRICLE AORTA LIGAMENTUM TERES PORTAL VEIN URACHUS INFERIOR VENA CAVA UMBILICAL A. Fig. 379. Diagrams of probable fetal and postpartum circulations through the heart in the mammal. (A) Fetal circulation. Oxygenated blood passes through umbilical vein, to liver. Passing through the liver by means of the ductus venosus it gathers blood from the liver veins and empties into the inferior vena
. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. LEFT LUNG LIGAMENTUM ARTERl DUCTUS ARTERl RIGHT AT RIGHT VENTRICLE AORTA LIGAMENTUM TERES PORTAL VEIN URACHUS INFERIOR VENA CAVA UMBILICAL A. Fig. 379. Diagrams of probable fetal and postpartum circulations through the heart in the mammal. (A) Fetal circulation. Oxygenated blood passes through umbilical vein, to liver. Passing through the liver by means of the ductus venosus it gathers blood from the liver veins and empties into the inferior vena cava through the hepatic vein. Within the inferior vena cava it mixes with non-oxygenated blood from the posterior part of the body. Reaching the right atrium it passes across the atrium through the foramen ovale and into the left atrium and from thence into left ventricle. The blood from the superior vena cava crosses to one side of the blood current from the inferior vena cava in the right atrium on its way to right ventricle. Most of the blood from the right ventricle courses through the ductus arteriosus into the descending aorta. A small amount goes to the lungs via the pulmonary arteries. (B) Circulation after birth. Observe there is no passage of blood from the right atrium into the left atrium. The blood in the left atrium is returning oxygenated blood from the lungs. The ductus arteriosus has atrophied. (See text.) (A redrawn and modified from Windle, 1940, Physiology of the Fetus, Saunders, Philadelphia. B adapted from A.) and excretory regions before birth and hatching. The circulatory system therefore must accommodate these areas in the fulfillment of the respiratory and excretory functions. However, at the same time the developing heart and immediate blood vessels in relation to the heart also must look forward, as it were, to the requirements of the period after birth (mammals) or after hatching (reptiles and birds). A diagram of the circulation of the blood throu
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