1. Development of the Circulatory System
Development of cardiovascular system
Development of lymphatic vascular system

2. overview The cardiovascular system is derived from the mesoderm.
It appears in the middle of the 3rd week.
Blood circulation starts by the end of the 3rd week.
Some changes take place at birth and in the 1st postnatal month.

3. Key points Development of primitive cardiovascular system
Development of Heart
Formation and modification of aortic arches
Circulation before and after birth
Congenital Malformations ※

5. Primitive Cardiovascular System
Oropharyngeal membrane
Cardiogenic area

6. Primitive cardiovascular system
Yolk sac
mesenchyme cells
blood islands
Central C Peripheral C
Primitive Blood cell Endothelia C
Blood C Vessels
Endothelial tubes of intraembryo and extraembryo are connected with each other by body stalk.

7. primitive cardiovascular system
Yolk sac
mesenchyme cells
blood islands
Central C Peripheral C
Primitive Blood cell Endothelia C
Blood C Vessels
Vessels net
primitive cardiovascular system

8. ① heart tube：2 tubes 1 tube  Primitive heart ② arteries ③ veins
Heart tubes
20d 4w
End of 4w
① heart tube：2 tubes 1 tube  Primitive heart
② arteries
③ veins

9. ① heart tube ② arteries ③ veins 2 dorsal A  1 aorta，many branches
Aortic arches
Dorsal aorta
20d 4w
End of 4w
Vitelline A
Umbilical A
① heart tube
② arteries
③ veins
2 dorsal A  1 aorta，many branches
Few pairs of vitelline A
1 pair of umbilical A
6 pairs of aortic arches

10. ① heart tube ② arteries ③ veins 1 pair of anterior cardinal V
A cardinal V
Posterior
Vitelline V
Common cardinal V
Umbilical V
20d 4w
End of 4w
① heart tube
② arteries
③ veins
1 pair of anterior cardinal V
1 pair of posterior cardinal V
1 pair of vitelline V
1 pair of umbilical V
Common
cardinal V
heart

11. Three separate circulations
vitelline, umbilical and embryonic circulation.

12. Development of the Heart
►Development of the heart tube
► Morphogenesis of the heart
► Partitioning of Heart Chambers
► Development of sinus venosus and differentiation of veins

13. Development of the heart tube
Cardiogenic area
Oropharyngeal membrane
Cardiogenic area is anterior to the oropharyngeal membrane and the neural plate.

14. Development of the heart tube
Pericardial cavity
Buccopharyngeal M
cardiaogenic plate
About 18~19d, a cavity appears in the cardiogenic area
--pericardiac cavity
B. Ventral of the cavity is cardiaogenic cords
--cardiaogenic plate

15. Development of the heart tube
Pericardial cavity
cardiac tube
The 20th d
C. cardiaogenic plate becomes hollow--cardiac tube

16. Development of the heart tube
Pericardial cavity
cardiac tube
The 22nd d
D. As the embryo folds cephalocaudally, the developing heart tube bulges more and more into the pericardial cavity.

17. Development of the heart tube
Pericardial cavity
cardiac tube
The 28th d
E. The paired heart tubes merge except at their caudalmost ends.
F. The tube remains attached to the dorsal side of the pericardial cavity by the dorsal mesocardium.

18. Development of the heart tube
Caudal end
Cephalic end
Heart tube
Pericardial cavity
G. Cephalic end  Arteries，Caudal end  Veins

20. Pericardial cavity

21. Wall of primitive heart tube
Endocardial heart tube → endocardium
Myoepicardial mantle → myocardium, epicardium
Cardiac jelly → subendocardial tissue

22. Morphogenesis of the heart
Vein end
Cardiac tube
Artery end
A. Part of the cardiac tubes merged
B. Cephalic end A
Caudal end V
The 21st d

23. Morphogenesis of the heart
atrium
ventricle
bulbus cordis
C. Heart tubes almost merged
D. Three expansions
bulbus cordis(心球)
Ventricle(心室)
Atrium(心房)
The 22nd d

24. Morphogenesis of the heart
truncus
arteriosus
E. The 4th expansion, the sinus venosus(静脉窦) appears
F. The truncus arteriosus(动脉干)appears
G. The heart tube starts to bend
bulbus
cordis
ventricle
atrium
sinus
venosus
The 23rd d

25. Morphogenesis of the heart
The cephalic portion
bends ventrally,
caudally, and to the
right. The caudal part
shifts dorsocranially
and to the left. Form a
‘U’ like structure, the
cardiac loop
(bulboventricular loop).
truncus
arteriosus
Bulboventricular
loop
Sinus venosus
The 24th d

26. Morphogenesis of the heart
I. The bulboventricular
loop keeps turning, the
atrium shifts to the
cephalodorsal of the
ventricle
G. Two atria and two
ventricles
Aortic
arches
atrium
ventricle
The 35th d
The normal heart shape was established,
but partitioning has not completed

29. Development of the Heart
►Development of the heart tube
► Morphogenesis of the heart
► Partitioning of Heart Chambers
► Development of sinus venosus and differentiation of veins

30. Partitioning of Heart Chambers
►Division of atrioventricular canal
► Partitiioning of the primitive atrium
► Partitioning of the primitive ventricle
► Division of truncus and bulbus

31. Subendocardial tissue → dorsal and ventral endocardial cushions
→ fuse → right and left canals

33. Septum formation in part arises from development of endocardial cushion. Many malformations are related to abnormal cushion morphogenesis.
atria
Endocardiac
cushion
ventricle
The 4th w

34. The 5th w Fusion of the opposing superior and inferior
cushions divides the
orifice into R and L
aterioventricular canals.
Endocardiac
cushion
L AV orifice
R AV orifice
The 5th w

35. The 4th month Left biscuspid Right tricuspid bicuspid tricuspid
Endocardiac
cushion
Left
Right
biscuspid
tricuspid
bicuspid
tricuspid
The 4th month

36. Partitioning of Heart Chambers
►Division of atrioventricular canal
► Partitiioning of the primitive atrium
► Partitioning of the primitive ventricle
► Division of truncus and bulbus

37. A. Septum primum(原发隔/第一房间隔) grows down and fuses with the EC.
B. There is a small
opening between the two
chambers, foramen primum (原发孔)
Septum
primum
foramen
primum
Endocardiac
cushion
The 4th w

38. Early 5th w C. The foramen primum hasn’t closed.
D. There are few small holes on the septum primum.
Small holes
foramen primum
Early 5th w

39. Septum
secundum
E. Septum secundum (继发隔/第二房间隔)appears on the right of the septum primum.
F. Small holes fuse to form the foramen secundum(继发孔/第二房间孔).
G. The foramen primum closed.
Foramen
secundum
Septum
primum
End of the 5th w

40. Septum
secundum
Foramen
secundum
H. Septum secundum extends downward to cover the foramen secundum, but leaving an opening, foramen ovale(卵圆孔)
I. The septum primum covers the foramen ovale, serves as a valve.
Septum
primum
Foramen
ovale
Early 6th w

41. G. Blood
L atrium R R
L atrium
K. After birth, the foramen ovale closed complete, and atrium is separated into R and L atria.

42. Partitiioning of the primitive atrium

43. Partitioning of Heart Chambers
►Division of atrioventricular canal
► Partitiioning of the primitive atrium
► Partitioning of the primitive ventricle
► Division of truncus and bulbus

44. The muscular Interventricular septum(室间隔肌部) grows up from the floor of the ventricle.EC LV RV
Inter-ventricular septum
The 4th w

45. B. The muscular interventricular septum keeps growing up, an interventricular foramen(室间孔) remains.EC
Inter-
ventricular
foramen
IV septum
End of the 5th w

46. C. Membranous interventricular septum(室间隔膜部) derived from the EC, closes the interventricular foramen. EC
Membranous
IV septum
IV septum
End of the 7th w

47. Left ventricle Pulmonary artery Right ventricle Aorta
The interventricular septum=muscular part
+ membranous portion
Left ventricle Pulmonary artery
Right ventricle Aorta

48. Partitioning of Heart Chambers
►Division of atrioventricular canal
► Partitiioning of the primitive atrium
► Partitioning of the primitive ventricle
► Division of truncus and bulbus

49. truncal ridge Truncus arteriosus bulbar ridge Bulbus cordis
The 5th w
truncal ridge
Truncus
arteriosus
bulbar ridge
Bulbus cordis
A. Two spiral truncal ridges(动脉干嵴)/ bulbar ridges(心球嵴) grow from the inner walls of the truncus arteriosus and bulbus cordis.

50. C. Truncal ridges + Bulbar ridges → aorticopulmonary septum
Aorta
pulmonary
Aortico-
pulmonary
septum
B. These ridges grow into the truncus from either side and fuse in the middle.
C. Truncal ridges + Bulbar ridges → aorticopulmonary septum

51. D. The ridges spiral neatly down the truncus until they reach the ventricles.

52. E. Aorticopulmonary septum divides the bulbus and truncus into two channels: pulmonary trunk connecting to the right ventricle; aorta connecting to the left ventricle.

53. F. As the same time, the division of the ventricle is completed.

54. Development of the Heart
►Development of the heart tube
► Morphogenesis of the heart
► Partitioning of Heart Chambers
► Development of sinus venosus and differentiation of veins

55. Three separate circulations
vitelline, umbilical and embryonic circulation.

56. 卵黄静脉
Ductus venosus
（肝血窦）
门静脉

57. Primitive plumary vein

58. Formation and modification of aortic arches

59. Circulation before and after birth

60. Before birth
Placental circulation: umbilical A. & V.

61. 80%
O2 saturation
58%

62. After birth Umbilical arteries→ lateral umbilical ligaments
Umbilical vein →
ligamentum teres hepatis
Ductus venosus →
venous ligament
Ductus arteriosus →
arterial ligament
Foramen ovale →
oval fossa

63. 胎儿出生后血液循环的变化 胎盘血循环中断→下腔静脉和右心房的血压下降 肺开始呼吸（肺充气）→肺血管阻力显著下降→肺血流量明显增加
→左心房的血压高于右心房
脐动脉：大部分→脐侧韧带；
近侧段→膀胱上动脉
脐静脉→肝圆韧带
静脉导管→静脉韧带
动脉导管→动脉韧带
(生后 3 个月左右)
卵圆孔→卵圆窝
(生后 1 年左右)

65. Atrial septal defect(房间隔缺损 )
Primum type involves the endocardial cushions.
Secundum type involves septum primum or septum secundum.
There is communication between the right and left atria which causes a left to right shunting of blood due to the lower pressure in the pulmonary circulatory system. Consequently there is a mixing of oxygenated (systemic) and deoxygenated (pulmonary) blood.

66. Ventricular septal defect(室间隔缺损 )
Defect of the membranous septum, isolated or associated with other abnormalities. There is a massive left to right shunting of blood and pulmonary hypertension.

67. Tetralogy of Fallot(法洛四联症)
Unequal division of truncus and bulbus :
a large aorta
a smaller pulmonary trunk
(1) Pulmonary stenosis
(2) Overriding aorta (the aorta straddles the VSD)
(3) Ventricular septal defect (VSD) of the membranous portion
(4) The walls of the right ventricle to expand. right ventricular hypertrophy due to the shunting of blood from left to right.

68. Patent ductus arteriosus(动脉导管未闭)
Ductus arteriosus fails to be closed after birth. Blood will be shunted from the aorta to the lungs, eventually causing irreversible pulmonary hypertension.

69. Thank you !