The Cardiovascular System (Part I) 黃敏銓
德國敏斯特大學 細胞生物學/遺傳學 博士 解剖學暨細胞生物學研究所 助理教授 1 The Cardiovascular System
1. The first major system to function 2. The primordial heart and vascular system appear in the middle of the third week 3. The heart starts to function at the beginning of the fourth week
2 The cardiovascular system is derived mainly from:
• Splanchnic mesoderm
• Paraxial and lateral mesoderm
• Neural crest cells
3 Development of heart
4 Eraly development of heart
Heart primordium
Angioblastic cord
18 days Angioblastic cord
5 Development of veins
Three paired veins drain into the tubular heart of a 4-week embryo
• Vitelline veins: poorly oxygenated blood from yolk sac • Umbilical veins: oxygenated blood from the primordial placenta • Common cardinal veins: poorly oxygenated blood from the body of the embryo
6 Three paired veins Cardinal veins 26 days Sinus venosus
Blue color
Vitelline vein Umbilical vein
7 Three paired veins enter into the sinus venosus
Left Right
Dorsal view 24 days 8 Vitelline veins Hepatic vein and portal vein
Left Right
Hepatic vein: right vitelline vein
Liver
Portal vein: vitelline veins
9 Dorsal view (7 weeks) Duodenum Umbilical veins Umbilical vein & ductus venosus: left umbilical vein
Left Right
7th week
(Ligamentum venosum)
10 Dorsal view Anterior cardinal veins 1. Brachiocephalic veins 7 weeks Anastomosis between anterior cardinal veins
Left Right
8 weeks Left brachiocephalic vein Right brachiocephalic vein
11 Dorsal view Superior vena cava
Dorsal view
Superior vena cava
Right anterior cardinal vein Right common cardinal vein
12 Left Right Posterior cardinal veins: root of azygos v. and common iliac veins
6 weeks Adult
Azygos v.
Posterior cardinal vein (mesonephroi)
Common iliac v.
13 Right Left Subcardinal veins and supracardinal veins replace and supplement posterior cardinal veins
Supracardinal v.
Posterior cardinal v. Subcardinal v.
Right Left
6 weeks 7 weeks 14 Subcardinal veins
IVC (prerenal seg.) Stem of L. renal v.
R. suprarenal v. L. suprarenal v.
Subcardinal vein R. gonadal v. L. gonadal v.
6 weeks Adult 15 Right Left Supracardinal veins
Azygos v. Hemiazygos v.
IVC (postrenal seg.) degeneration
8 weeks Right Adult Left
16 Supracardinal vein Inferior vena cava (IVC)
IVC (hepatic segment): hepatic v. and sinusoids
IVC (prerenal segment): R. subcardinal v.
IVC (renal segment): Subcardinal-supracardinal anastomosis
IVC (postrenal segment): R. supracardinal v.
17 Right Adult Left Dorsal intersegmental arteries Aortic arches Dorsal aorta
Pharyngeal arches
Aortic sac
4th-5th week (26 days)
18 Dorsal intersegmental arteries
•Neck: vertebral arteries •Thorax: intercostal arteries • Abdomen: – lumbar arteries – 5th pair: common iliac arteries •Sacrum: lateral sacral arteries • Caudal end of dorsal aorta: median sacral artery.
• Celiac trunk: foregut
• Superior mesenteric artery: midgut
• Inferior mesenteric artery: hindgut
20 Umbilical arteries
• Proximal parts – Internal iliac arteries – Superior vesical arteries • Distal parts – Medial umbilical ligments
21 Further development of heart
22 Fusion of endocardial heart tubes
Ventral views
23 Fusion of endocardial heart tubes
Pericardial coelom 20-day
Dorsal mesocardium
Epicardium
Cardiac jelly 22-day Primordial myocardium 24 (from splanchnic mesoderm) Formation of heart wall and transverse pericardial sinus
Endocardium
Sinus venosus Myocardium
Epicardium
28 days 25 Transverse pericardial sinus
26 Relative position of human embryo during the 4th week
Head fold
Oropharyngeal membrane
foregut Tubular heart formation
Septum transversum
Pericardial cavity 27 U-shaped bulboventricular loop
Primordial atrium
Sinus venosus Truncus arteriosus
Bulbus cordis
Primordial ventricle
24 days 28 Lateral expansions of the sinus venosus
Left horn of sinus venosus
Right horn of sinus venosus
Dorsal view of the heart (about 26 days) 29 Circulation through primordial heart
6
Sinus venosus 1
2
3
5
4 30 End of 4th week: unidirectional flow 休息10分鐘
31 Partitioning of primordial heart
• begins around middle of the 4th week. •is completed by the end of the 5th week. • includes partitioning of: – Atrioventricular canal – Primordial atrium – Primordial ventricle
32 Partitioning of Atrioventricular Canal
5th week
Fused endocardial canal
End of 4th week
Endocardial cushions (from cardiac Left AV canal jelly)
Transformed endocardial cushions contribute to the 33 formation of valves and membranous septa of the heart. AV endocardial cushions
the primordia of the valves and membranous septa
Bone morphogenetic protein (BMP2)
34 Partitioning of primordial atrium
• begins at the end of the 4th week. • is divided into right and left atria by: – Septum primum – Septum secundum
35 Septum primum
Septum primum
Endocardial cushion
Septum secundum
Foramen secundum
Foramen primum
36 Septum primum
Septum primum
Foramum primum
Foramum primum
Foramum secundum
Foramum primum
Septum secundum
Foramum secundum
Septum primum 37 Septum secundum
Septum secundum (upper limb) Foramen secundum Oval foramen
Valve of oval foramen (from septum primum)
Oval foramen
Valve (from septum primum)
38 Valve of oval foramen
Septum primum
Septum secundum
Oval foramen (open)
Valve of oval foramen
39 Oval fossa is a remnant of oval foramen
Before birth After birth
Septum secundum
Oval fossa Oval foramen Septum primum (valve of oval foramen)
40 Development of sinus venosus
Opening of sinus venosus into primordial atrium Left horn of sinus venosus Right horn of sinus venosus
Left Right
Dorsal view (4 th week) 41 Progressive enlargement of the right horn results from two left-to-right shunts of blood
Dorsal view (7 weeks)42 Left Right Doral view
Primordial atrium
26 days Right horn of sinus venosus
Left horn of sinus venosus
Sinus venarum of right atrium 8 weeks
Coronary sinus
43 Left Right Right sinuatrial valve → Left sinuatrial valve → • Crista terminalis fused with septum secundum → • Valve of IVC Interatrial septum • Valve of coronary sinus
Crista terminalis
Valve of coronary sinus
Valve of inferior vena cava 44 Right Left Absorption of pulmonary vein into left atrium
5 weeks 6 weeks
Primordial pulmonary vein
Primordial left atrium
Smooth-walled part of left atrium
Left auricle 8 weeks 45 Right Left Myocardial sleeves
atrial fibrillation
46 Partitioning of primordial ventricle
Fused endocardial cushions
Interventricular foramen Expansion Interventricular septum 5th week (muscular part)
47 Right Left Closure of the interventricular foramen
Right bulbar ridge Left bulbar IV foramen ridge
Fused endocardial cushions
Membranous part of IV septum
48 7 weeks Cavitation of the ventricular walls forms a sponge-work of muscular bundles – trabeculae carneae
5 weeks 6 weeks
20 weeks
Chordae tendinae 7 weeks Trabeculae carneae Papillary muscle 49 Right Left Partitioning of Bulbus Cordis and Truncus Arteriosus
Truncus arteriosus Truncal ridge Bulbus cordis
Bulbar ridge 5 weeks
Aorta Aorticopulmonary septum Pulmonary trunk
6 weeks
50 Spiral form of Aorticopulmonary Septum
51 Bulbus cordis incorporates into the walls of ventricles
Conus arteriosus (infundibulum)
Aortic vestibule
52 Development of cardiac valves
Swellings of subendothelial tissue Dorsal valve swelling
Bulbar ridges Ventral valve swelling
53 Hollowing and thinning of valve swellings
Valve swelling
54 Conducting system of heart
Sinuatrial node (5 th week)
Atrioventricular node
Atrioventricular bundle Branches of AV bundle Right Left 55