1. 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

2. 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

3. 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

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

5. 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

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

7. 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

8. 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)

9. 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

10. Establishment of configuration of heart
Truncus arteriosus
Atrium
Bulbus
cordis
Ventricle

11. Establishment of configuration of heart

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

13. 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:

14. 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

15. Compartmentation of primitive atrium

16. 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

17. 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

18. Development of heart (6th week)
Muscular interventricular septum

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

20. 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 ）

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

22. Development of heart (6th week)
Bulbar ridge

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

24. Blood circulation of fetus

25. Venous ductus

26. Arterial ductus

29. 3 2 1 Characteristics Umbilical vessels－－2 A , 1 V
Ductus－－A ductus、V ductus
Foramen－－Foramen ovale　

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

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

32. 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

33. 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

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

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

37. 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

39. Patent ductus arteriosus
Ductus arteriosus remains open

40. Right positioned heart