1. NOTICE
Saturday morning & afternoon theory lesson !!! 1

2. Development of Cardiovascular system

3. Key points Development of primitive cardiovascular system
Development of Heart
Circulation before and after birth
Congenital Malformations 3

4. Inner cell mass→2 layers of cell in disc (7th day)
Epiblast: columnar cells
Hypoblast: cuboidal cells
Decidua
Syncytiotrophoblast
Epiblast
Hypoblast
Primary
yolk sac
Amniotic cavity
Cytotrophoblast
Nutritional requirements by diffusion 4

5. 5

6. Primitive streak 6

7. Yolk sac mesenchyme cells
1. Development of Early Blood Vessels(3rd)
Yolk sac
mesenchyme cells
blood islands
Central C Peripheral C
Hematopoietic endothelia
cell
Blood C Vessels
induce by FGF

8. Hematogenous organs Time Organ 3~6 wk Yolk sac 6~11 wk Liver
12 wk~5 month
Spleen
From 2 month on
Bone marrow 8

9. Endothelial tubes expanded outgrowth from the wall and form meshwork
Endothelial tubes form in same manner in stalk and chorion in 19th days.
Endothelial tubes expanded outgrowth from the wall and form meshwork
3rd,intraembryo and extraembryo are conneted with each other by body stalk. 9

10. Blood vessel development occurs by two mechanisms:
vasculogenesis ,the major vessels, including the dorsal aorta and cardinal veins, are formed by vasculogenesis.
angiogenesis whereby vessels sprout from existing vessels. the remainder of the vascular system then forms by angiogenesis. 10

11. primitive cardiovascular
system
1.1 Formation
Vessels net 11

12. 1.2 Component ① heart tube：2 tubes 1 tube  Primitive heart
Heart tubes
20d 4w
End of 4w
① heart tube：2 tubes 1 tube  Primitive heart
② arteries
③ veins
① heart tube：2 tubes 1 tube  Primitive heart
② arteries
③ veins 12

13. 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
two dorsal aortae combine to become the descending aorta in later development. 13

14. 3. Formation and modification of aortic arches14

15. Formation and modification of aortic arches
third —carotid arteries (internal and external artery
Left fourth– arch of the aorta
Right fourth-right subclavian
artery
Sixth(left)– pulmonary
artery&ductus arteriosus
sixth (right )--disappears 15

16. ① heart tube ② arteries ③ veins Common 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 16

17. 1.3 Three separate circulations (end of 4th week)
vitelline, umbilical and embryonic circulation. 17

18. By the end of the 3rd week:
The embryo has a system of paired vessels.
The vessels forming the heart have fused.
Three separate circulations
vitelline, umbilical and embryonic circulation. 18

19. 2. Development of the Heart
2.1 Development of the heart tube
2.2 Morphogenesis of the heart
2.3 Partitioning of Heart Chambers
2.4 Development of sinus venosus and differentiation of veins 19

20. 2.1 Development of the heart tube
Cardiogenic area
Buccopharyngeal
membrane
Cardiogenic area is anterior to the buccopharyngeal membrane and the neural plate. 20

21. 2.1 Development of the heart tube
Pericardial cavity
cardiac tube
The 20th d
C. cardiaogenic plate becomes hollow--cardiac tube 21

22. 2.1 Development of the heart tube
Pericardial coelom
cardiac tube
The 22nd d
CNS grow cephalad so rapidily that it extends over the cardiogenic area and pericardial cavity, buccophangeal membrane is pulled forward ,the heart and percardial cavity move first the cervial region and finally to the thorax
D. As the embryo folds cephalocaudally, the developing heart tube bulges more and more into the pericardial cavity. 22

23. 2.1 Development of the heart tube
Pericardial coelom
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. 23

24. 2.1 Development of the heart tube
Transverse sinus
Heart tube
Pericardial cavity
G. The dorsal mesocardium disappears, creating the transverse pericardial sinus.
H. Cephalic end  Arteries，caudal end  Veins 24

25. Wall of primitive heart tube
Endocardial heart tube → endocardium
Myoepicardial mentle → myocardium, epicardium
Cardiac jelly → subendocardial tissue 25

26. 2. Development of the Heart
2.1 Development of the heart tube
2.2 Morphogenesis of the heart
2.3 Partitioning of Heart Chambers
2.4 Development of sinus venosus and
differentiation of veins 26

27. 2.2 Morphogenesis of the heart
The 21st d
Vein end
Cardiac tube
Artery end
A. Part of the cardiac tubes merged
B. Cephalic end A
Caudal end V 27

28.                                  
                                  28

29. 2.2 Morphogenesis of the heart
The 22nd d
atrium
ventricle
bulbus cordis
C. Heart tubes almost merged
D. Three expansions
bulbus cordis
ventricle
atrium 29

30. 2.2 Morphogenesis of the heart
The 23rd d
truncus
arteriosus
E. The 4th expansion, sinus venosus appears
----caudal end
F. truncus arteriosus appears --cephalic end
G. The heart tube starts to bend
bulbus
cordis
ventricle
atrium
sinus
venosus 30

31. As the heart tube elongates and begins to loop, the blood flows into the sinus venosus, then into the primitive atria, ventricles and bulbous cordis before entering the visceral arch vessels.
                           
                                        31

32. 2.2 Morphogenesis of the heart
The 24th d
truncus
arteriosus
The cephalic portion
bends ventrally,
caudally,and to the
right. The caudal part
shifts dorsocranially
and to the left. Form a
‘U’ shape structure----
cardiac loop
(bulboventricular loop).
Bulboventricular
loop
Sinus venosus 32

33. bulbus cordis proximal third -----primitive the right ventricle.
midportion( the conus cordis)----outflow tracts of both ventricles.
distal bulbus(the truncus arteriosus)---roots and proximal portion of the aorta and pulmonary artery 33

34. 2.2 Morphogenesis of the heart
The 35th d
Aortic
arches
I. The bulboventricular
loop keeps turning, the
atrium shifts to the
cephalodorsal of the
ventricle
G. Two atria and two
ventricles
atrium
ventricle
The normal heart shape was established,
but partitioning has not completed 34

35. 2. Development of the Heart
2.1 Development of the heart tube
2.2 Morphogenesis of the heart
2.3 Partitioning of Heart Chambers
2.4 Development of sinus venosus and
differentiation of veins 35

36. 2.3 Partitioning of Heart Chambers
Division of atrioventricular canal
Partitiioning of the primitive atrium
Partitioning of the primitive ventricle
Division of truncus and bulbus 36

37. Division of atrioventricular canal
Subendocardial tissue → 2 endocardial cushions → fuse → right and left canals 37

38. The 5th w 2.3.1 Division of atrioventricular canal
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 38

39. Partitioning of primitive atrium(4th)
1) Septum primum(sickle-shaped) → endocardial cushions → ostium primum. 39

40. Looking into the atrial chambers, the septum primum and its union with the endocardial cushions are evident 40

41. 2) Septum primum absorbed → ostium secundum → ostium primum closing
3) Septum secundum(crescent-shaped) → cover the ostium secundum → ovale foramen 41

42. Early 6th w Partitioning of the primitive atrium
Septum
secundum
Foramen
secundum
H. Septum secundum extends downward to cover the foramen secundum, but leaving an opening, foramen ovale
I. The septum primum covers the foramen ovale, serves as a valve.
Septum
primum
Foramen
ovale
Early 6th w 42

43. 4) Blood from right to left atrium ovale foramen43

44. Partitioning of the primitive atrium
From R
G. Blood
L atrium R
L atrium
K. After birth, lung circulation begin and pressure in left atrum increase,the oval foramen is pressed agaimst the septum secundum,obliterating the oval foramen-- 44

45. Summary Development of the heart tube Development of the heart
Morphogenesis of the heart
Partitioning of Heart Chambers 45

46. 2.3.3. Partitioning of the primitive ventricle ( 4th)
The muscular
Interventricular septum
grows up from the floor
of the ventricle. EC LV RV
Inter-ventricular septum
The 4th w 46

47.                                                                             
Frontal section through the heart of an embryo at the end of the seventh week. The conus septum is complete, and blood from the left ventricle enters the aorta. Note the septum in the atrial region. 47

48. 2.3.3. Partitioning of the primitive ventricle
B. The muscular interventricular septum keeps growing up, an interventricular foramen remains. EC
Inter-
ventricular
foramen
IV septum
End of the 5th w 48

49. 2.3.3. Partitioning of the primitive ventricle
C. Endocardial cushion, right and left bulbar ridges → membranous interventricular septum → interventricular foramen closed EC
Membranous
IV septum
IV septum
End of the 7th w 49

50. 2.3.3. Partitioning of the primitive ventricle
The interventricular septum=muscular part
+ membranous portion

51. 2.3.4. Division of truncus and bulbus
The 5th w
truncal ridge
Truncus
arteriosus
bulbar ridge
bulbus
A. Two spiral truncal ridges grow from the inner walls, and bulbar ridges also form in the bulbus. 51

52. 2.3.4. Division of truncus and bulbus
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 52

53. 2.3.4. Division of truncus and bulbus
D. The ridges spiral neatly down the truncus until they reach the ventricles. 53

54. 2.3.4. Division of truncus and bulbus
E. Aorticopulmonary septum divides the bulbus and truncus into two channels: pulmonary trunk connecting to the right ventricle; aorta connecting to the left ventricle. 54

55. 2.3.4. Division of truncus and bulbus
F. As the same time, the division of the ventricle is completed. 55

56. Truncus swellings → hollowed out at upper surface → semilunar valves
5 week 6 week 7week
6 week week week 56

57. 2.4 Development of sinus venosus and differentiation of veins
middle of the fourth week, three important veins: (a) the vitelline (b) the umbilical vein, (c) the common cardinal vein.
communication between the sinus and the atrium is wide.
the entrance of the sinus shifts to the right .caused by left-to-right shunts of blood, 57

58. 2.4 Development of sinus venosus and differentiation of veins
Fifth, right umbilical vein and the left vitelline vein obliteration--the left sinus horn loses its importance
10 weeks , left common cardinal vein obliterated, left sinus horn is the oblique vein of the left atrium and the coronary sinus 58

59. 2.4 Development of sinus venosus and differentiation of veins
right sinus horn and veins enlarge greatly.
The right horn,----incorporated into the right atrium to form the smooth-walled part of the right atrium , develops into two parts: (a) the valve of the inferior vena cava, and (b) the valve of the coronary sinus
left venous valve and the septum spurium fuse with the developing atrial septum 59

60. the primitive left atrium is expanding
the primitive left atrium is expanding. a single embryonic pulmonary vein
During further development, the pulmonary vein and its branches are incorporated into the left atrium, forming the large smooth-walled part of the adult atrium. four pulmonary veins enter as the branches are incorporated into the expanding atrial wall. 60

61. Sinus-atrial orifice → right;
Right horn enlarges (due to left-to-right shunts of blood in venous system)
Sinus-atrial orifice → right;
Receives superior and inferior vena cava;
Right horn → right atrium (smooth walled part). 61

62. Pulmonary vein and its branches → left atrium (smooth walled part)
2) Left horn degenerates → coronary sinus, oblique vein of left atrium;
Pulmonary vein and its branches → left atrium (smooth walled part) 62

63. 4. Circulation before and after Birth
before birth
Placental circulation: umbilical A. & V.
ductus venosus
foramen ovale
ductus arteriosus 63

64. 58%
80%
O2 saturation 64

65. Changes after birth Umbilical arteries
proximal portion—superior vesical arteries
distal parts—medial umbilical ligaments
Umbilical vein → ligamentum teres hepatis
Ductus venosus → ligament venous
Ductus arteriosus → arterial ligament
Foramen ovale → oval fossa 65

66. Congenital Malformations
Atrial septal defect
Excessive resorption of the septum primum;
Inadequate development of the septum secundum. 66

67. Ventricular septal defect
Defect of the membranous septum, isolated or associated with other abnormalities. 67

68. In the case of a VSD there is a massive left to right shunting of blood and pulmonary hypertension. The absence of the interventricular septum results in a Common Ventricle. 68

69. Unequal division of conus cordis;
Tetralogy of Fallot
Unequal division of conus cordis;
4 defects: pulmonary stenosis, overriding aorta, ventricular septal defect, hypertrophy of right ventricle;
Causing cyanosis(发绀） 69

70. Persistent truncus arteriosus
Truncoconal ridges fail to fuse and descend;
Truncus overrides both ventricles;
Accompanied by ventricular septal defect;
Cyanosis, blood to lungs increased. 70

71. Absence or fusion of tricuspid valves;
Tricuspid atresia
Absence or fusion of tricuspid valves;
Patent oval foramen & ventricular septal defect;
Underdeveloped right ventricle 71

72. 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. 72

73. Formation and division of the heart tube;
SUMMARY
Formation and division of the heart tube;
Partitioning of atrioventricular canal, autrium, ventricle, and truncus and bulbus;
Congenital heart diseases. 73