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. Division of atrioventricular canal
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