Cardiovascular System Development PDF

15/11/2023 Cardiovascular System Hytell et al (2010) Chapter 12 Melvin A. Bagot, DVM MSc 1  15/11/2023 Formation of blood and blood vessels Development of the blood cells,...

15/11/2023 Cardiovascular System Hytell et al (2010) Chapter 12 Melvin A. Bagot, DVM MSc 1  15/11/2023 Formation of blood and blood vessels Development of the blood cells, Cardiogenic field heart and vascular system 2  15/11/2023 Development of the blood cells, Endocardial tube heart and vascular system Development of the blood cells, Endocardial tube heart and vascular system 3  15/11/2023 Development of the blood cells, Dorsal aortae heart and vascular system Ventral aortae 4  15/11/2023 Additional info 5  15/11/2023 Somatic circulation 6  15/11/2023 Formation of blood vessels Mesoblastic period Hematopoiesis Hepato-lineal period Medullary period Angiogenesis is the formation of new blood vessels. This process involves the migration, growth, and differentiation of endothelial cells, which line the inside wall of blood vessels. Vasculogenesis is the process of blood vessel formation occurring by a de novo production of endothelial cells. 7  15/11/2023 Heart 8  15/11/2023 Primitive Heart Regions 1. Truncus arteriosus 2. Bulbus cordis 3. Ventricle 4. Atrium 5. Sinus venosus Primitive Heart Regions 1. Truncus arteriosus 2. Bulbus cordis 3. Ventricle 4. Atrium 5. Sinus venosus 9  15/11/2023 Formation of a Tubular Heart Fig. 12-1: A: Dorsal view of an embryo after removal of the amniotic folds. The cardiogenic field (1) is seen as a horseshoe-shaped structure anteriorly. 2: Neural plate; 3:Neural groove; 4: Cut edge of chorioamniotic fold; 5: Primitive node; 6: Primitive streak. B: Transverse section of embryo at the line ‘B’. 7: Neural ectoderm; 8: Mesoderm; 9: Endoderm; 10: Intra-embryonic coelom; 11: Visceral mesoderm; C: Median section through the embryo. 12: Cardiogenic field; 13: Pericardial cavity. Formation of a Tubular Heart 10  15/11/2023 Formation of a Tubular Heart Formation of a Tubular Heart 11  15/11/2023 Forming of a Four-Chambered Heart 1. Endocardial tube lengthens and loops on itself 2. Venous return is shifted to the right side 3. Atrio-ventricular opening is partitioned 12  15/11/2023 Forming a Four-Chambered Heart 4. Right and left ventricles formation 5. Division of right and left atria by a septum 6. Formation of aorta and pulmonary trunk Forming a Four-Chambered Heart 4. Right and left ventricles formation 5. Division of right and left atria by a septum 6. Formation of aorta and pulmonary trunk 13  15/11/2023 Atrio-ventricular opening is partitioned: Growth of endocardial “cushions” partitions the common A-V opening into right and left openings. Ventral growth of the cushions contributes to a septum that closes the interventricular foramen (the original opening between the bulbus cordis & ventricle). Incomplete closure of the interventricular septum (ventricular septal defect) results in blood flow from the left to the right ventricle and an associated murmur. Large defects produce clinical signs of cardiac insufficiency. Right and left atria divided by a septum: Septum formation is complicated by the need, until birth, for a patent (open) septum that allows blood to flow from the right atrium to the left. The septal opening is called the foramen ovale. Formation of the interatrial septum and foramen ovale: Interatrial Septum 1 grows from the dorsal atrial wall toward the endocardial cushions. The pre-existing Foramen 1 is obliterated when Septum 1 meets the endocardial cushion. Foramen 2 develops by fenestration of the dorsocranial region of Septum 1 (before Foramen 1 is obliterated). Interatrial Septum 2 grows from the cranial wall of the right atrium toward the caudal wall. The septum remains incomplete and its free edge forms the boundary of an opening called the Foramen Ovale. 14  15/11/2023 Forming a Four-Chambered Heart 4. Right and left ventricles formation 5. Division of right and left atria by a septum 6. Formation of aorta and pulmonary trunk Forming a Four-Chambered Heart Aorta and pulmonary trunk formed: The truncus arteriosus (and adjacent bulbus cordis) is partitioned in a spiral pattern in order to form the aorta & pulmonary trunk. Ridges appear along the lumen wall, grow inward and merge to create the spiral septum. As a result, the aorta and pulmonary trunk spiral around one another. 15  15/11/2023 Division of right and left atria by a septum Partitioning of the heart into four chambers. 1: Atrium; 2: Ventricle; 3: Bulbus cordis; 4: Cranial vena cava; 5: Caudal vena cava; 6: Septum primum; 7: Ostium primum; 8: Septum intermedium; 9: Left atrioventricular canal; 10: Right atrioventricular canal; 11: Interventricular septum; 12: Interventricular sulcus; 13: Foramen secundum; 14: Right atrium; 15: Left atrium; 16: Septum secundum; 17: Right ventricle; 18: Left ventricle; 19: Foramen ovale; 20: Cavitations in myocardium 16 15/11/2023 17  15/11/2023 Development of valves 1. Atrioventricular valves 2. Semilunar valves Bicuspid/mitral valves Tricuspid valves (Chordae tendineae) 18  15/11/2023 Tetralogy of Fallot 1. Ventricular septal defect 2. Stenosis of the pulmonary trunk 3. Enlarged aorta that overrides the right ventricle (dextroposition of the aorta) 4. Hypertrophy of the right ventricle, secondary to communication with the high pressure left ventricle. 19 15/11/2023 20