Development of circulatory system 1. Establishment of primitive cardiovascular system 2. Development of heart (1)　Formation of primitive heart (2)　Establishment of configuration of heart (3)　Compartmentation of heart 3. Blood circulation of fetus 4. Abnormality of circulatory system

Establishment of primitive cardiovascular system First: extraembryonic Second: endoembryonic Development of blood vessel 1. Extraembryonic (15th to 16th day) Endothelial tubular meshwork Endothelial tubule (periphery) Extraembryonic mesoderm (Yolk sac) Blood island Primitive blood cells (center) Extraembryonic mesoderm Body stalk, Chorion Endothelial tubular meshwork

Endothelial tubular meshwork 2. Endoembryonic (18th to 20th day) Endothelial tubular meshwork Endoembryonic mesoderm (Mesenchyme) Endothelial tubule 3. The end of 3rd week Endoembryonic Body stalk Extraembryonic Communication Primitive cardiovascular system

Formation of blood island and blood vessel Extraembryonic mesoderm Primitive blood cells Endothelium

Development of primitive heart 　Formation of primitive heart Fusion Pericardiac coelom 2 Cardiac tube 1 Head fold Cardiac tube 2 Pericardiac coelom 2 （dorsal） Cardiogenic region Fusion Cardiogenic plate 2 Cardiac tube 2 Pericardiac coelom 1 （Ventral） 18th-19th day

Head fold: Pericardiac coelom: dorsal → ventral Cardiac tube: ventral → dorsal

Lateral fold: Pericardiac coelom: 2 → 1 Cardiac tube: 2 → 1 2 1 3 4 Foregut Pericardiac coelom Cardiac tube 2 1 Dorsal mesocardium Cardiac tube Cardiac jelly Myocardium 3 4

Establishment of configuration of heart Straight tube (4th to 5th week) （21th day） 2 shrink Bulbus cordis —Ventricle— Atrium—Sinus venosus U-shaped bulboventricular loop Pericardial fixation Pericardiac fixation S-shaped Heart rudiment (35th day)

Bulboventricular loop Distal：slightness, truncus arteriosus Middle：dilation, bulbus arteriosus cordis Bulbus cordis Proximal：primitive right ventricle Ventricle Cardiac tube Atrium Left horn Sinus venosus Right horn Bulboventricular loop Protruding to right, ventral and tail

Establishment of configuration of heart Truncus arteriosus Atrium Bulbus cordis Ventricle

Establishment of configuration of heart

Compartmentation of heart 27-37th day 1 Compartmentation of heart 27-37th day 1.Compartmentation of atrioventricular tube Ventral endocardiac cushion Dorsal endocardiac cushion Left atrioventricular tube Right atrioventricular tube Atrioventricular tube

Compartmentation of primitive atrium ( 4th to 5th week) Septum primum: end of 4th week Foramen primum： Foramen secundum: Septum secundum: end of 5th week Foramen ovale: Valve of foramen ovale:

Forming foramen secundum Septum primum Left atrium Foramen primum Closing foramen primum Right atrium Septum secundum Foramen secundum Valve of forasmen ovale Foramen ovale Left ventricle Right ventricle

Compartmentation of primitive atrium

Compartmentation of primitive ventricle ( 4th to 8th week) Muscular interventricular septum：end of 4the week Interventricular foramen: Membranous interventricular septum: end of 7th week Three origins: left, right bulbar ridge and endocardiac cushion

Forming foramen secundum Septum primum Left atrium Foramen primum Closing foramen primum Interventricular foramen Muscular interventricular septum Septum secundum Foramen secundum Valve of foramen ovale Foramen ovale Left ventricle Right ventricle Membranous interventricular septum

Development of heart (6th week) Muscular interventricular septum

Formation of membranous septum Aortico-pulmonary septum Right bulbar ridge Left bulbar ridge Interventricular foramen Membranous interventricular septum Endocardiac cushion Muscular interventricular septum

Compartmentation of truncus arteriosus and bulbus cordis (5th to 8th week) Inner part of truncus arteriosus and bulbus cordis Aorta Fusion Aortico-pulmonary septum Left, right Bulbar ridge Pulmonary artery (Spiral) （Spiral ）

Aortico-pulmonary septum Right bulbar ridge Left bulbar ridge Aortico-pulmonary septum

Development of heart (6th week) Bulbar ridge

Compartmentation of truncus arteriosus and bulbus cordis Aortico-pulmonary septum Right pulmonary artery Aorta Aortico-pulmonary septum

Blood circulation of fetus

Venous ductus

Arterial ductus

3 2 1 Characteristics Umbilical vessels－－2 A , 1 V Ductus－－A ductus、V ductus Foramen－－Foramen ovale　

Alterations after birth ①Foramen ovale atresia ②Umbilical vessels atresia ③V ductus atresia ④A ductus atresia

Abnormality of circulatory system １. Atrial septal defect ２. Ventricular septal defect ３. Abnormal compartmentation of truncus arteriosus ４. Patent ductus arteriosus

Unclosed foramen ovale １. Atrial septal defect Unclosed foramen ovale Reasons： ① Perforation of foramen ovale ① ② ② Over absorption of septum primum ③ Undeveloped septum secundum ④ = ② + ③ ③ ④

２. Ventricular septal defect ②Muscular septal defect: sparsely ① Membranousr septal defect: commonly Reasons: ① Unfused endocardial cushion, bulbar ridge and muscular septum ② Over absorption of membranous septum Interventricular foramen Left ventricle Right ventricle

Abnormal compartmentation of truncus arteriosus ①Incorrectly positioned of aorta and pulmonary artery Aorta Reasons: No spiral Pulmonary artery Left ventricle Right ventricle

Abnormal compartmentation of truncus arteriosus ②Narrow of aorta or pulmonary artery Narrow pulmonary artery Reasons: Unequal compartmentation of aorta and pulmonary artery

Abnormal compartmentation of truncus arteriosus ③Tetralogy of Fallot Narrow pulmonary artery, ventricular septal defect, aorta stride and right ventricle hypertrophy Reasons: Unequal compartmentation of aorta and pulmonary artery Roght ventricle Left ventricle

Patent ductus arteriosus Ductus arteriosus remains open

Right positioned heart