DEVELOPMENTAL ANATOMY

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DEVELOPMENTAL ANATOMY Cardiovascular
System Dr. Sukumal Chongthammakun Department
of Anatomy, Faculty of Science Mahidol
University http//intranet.sc.mahidol/AN
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Development of Blood Vessels
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Development of Blood Vessels
Location Body, Connecting Stalk, Yolk Sac,
Chorion
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Development of Cardiogenic Area
Late presomite embryo (3rd week)

• Angiogenic clusters
• plexus of small blood vessels
• ant. portion cardiogenic area

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Development of cardiogenic area and pericardial
cavity
18 days
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Development of cardiogenic area and pericardial
cavity
18 days
intraembryonic coelom pericardial cavity
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Fusion of the Heart Tubes

• Head Flexion
• Rotation of cardiogenic area
• - caudal to prochordal plate
• - dorsal to septum transversum(diaphragm)
  intraembryonic coelom (pericardial cavity)

• Fusion of paired tubes

single tube
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Rotation of cardiogenic area pericardial cavity
180o rotation along a transverse axis
21 days
22 days
19-20 days
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Formation of a single heart tube
late presomite embryo (18 days)
early presomite embryo (17 days)
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Formation of a single heart tube

• 21 days (at 4 somites)
• Fusion of endocardial tubes

• 22 days (at 8 somites)
• Single endocardial tube

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Formation of Myoepicardial Mantle

• Splanchnic mesoderm surrounds the heart
• Cardiac jelly (extracellular matrix)
• - rich in collagen glycoproteins
• - play role in cardiac morphogenesis

Myoepicardial Mantle

• Myocardium
• Epicardium

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Formation of a single heart tube
21 days
22 days
Atrium is the last to fuse. Sinus horns are
embedded in the septum transversum.
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Subdivisions of the Primitive Heart (26 days)

• Lt. Rt. Aortic arches
• Aortic root
• Truncus arteriosus
• Bulbus cordis
• Ventricle
• Atrium
• Lt. Rt. horns of Sinus venosus

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Formation of the Cardiac Loop
1. Bulbus cordis bends in ventral caudal to
the right. 2. Atrium shifts in a dorsal
cranial direction. 3. Bulboventricular sulcus
is created.
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Formation of the Cardiac Loop

• U-shaped convexed forward and to the right
• Ventricular growth
• S-shaped bulboventricular sulcus in concaved
  loop

23 days (11 somites)
22 days (8 somites)
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Formation of the Cardiac Loop

• Primitive atrium moves up into the pericardial
  cavity

24 days (16 somites)
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Formation of the Cardiac Loop

• Atrium grows dorsally to the left
• Ventricle bulbus cordis grows ventrally to
  the right

28 days
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Formation of the Cardiac Loop
28days
1. Common atrium incorporated into pericardial
cavity. 2. Atrioventricular canal is
narrowed. 3. Bulbus cordis is narrowed, except
trabeculated part of right ventricle. 4. Conus
cordis will form outflow tracts of
ventricles. 5. Truncus cordis will form roots of
aorta pulmonary artery. 6. Bulboventricular
sulcus primary interventricular foramen.
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At the end of the loop formation
30 days
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Septum Formation in Common Atrium
30 days (6 mm.)
1. Endocardial cushions are formed in the AV
canal. 2. Septum primum grows from the roof of
common atrium. 3. Foramen (Ostium) primum is
formed. 4. Perforation appears in septum primum.
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Septum Formation in Common Atrium
33 days(9 mm.)
1. Endocardial cushion extends to close Foramen
primum. 2. Foramen (Ostium) secundum is
formed. 3. Fusion of endocardial cushions. 4.
Septum secundum grows downward/toward endocardial
cushion. 5. Foramen ovale is remained on the inf.
border of Septum secundum.
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Septum Formation in Common Atrium
Newborn
37 days (14 mm.)
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Septum Formation in Common Atrium
1. Septum secundum is never completed. 2. Left
venous septum spurium fuse with septum
secundum 3. Oval foramen is formed. 4. Septum
primum valve of oval foramen.
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Differentiation of Atria
35 days (7- to 8- mm)
Newborn
1. Right sinus horn incorporates into right
atrial wall smooth wall of right atrium
sinus venarum 2. Pulmonary vein develops as
outgrowth of left atrial wall smooth wall
of left atrium
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Development of Venous Valves
Newborn
35 days (7- to 8- mm)
1. Septum spurium fusion of Rt. Lt. venous
valves. 2. Sup. portion of Rt. venous valve
disappears. 3. Inf. portion of Rt. venous valve
valve of IVC valve of coronary
sinus 4. Crista terminalis dividing line
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Changes in Sinus Venosus

• 35 days
• 1. The veins to left sinus horn degenerates.
• 2. Right sinus horn moves to the right side.
• 8 week
• 1. Left sinus horn becomes coronary sinus
  oblique vein of the left atrium.
• 2. Right sinus horn incorporates into the wall of
  left atrium.
• 3. Sinuatrial orifice shifts to the right and is
  bordered by right left venous valves (Septum
  spurium).
• Left venous valves fuse with atrial septum
• Right venous valves Valve of IVC Valve of
  Coronary sinus

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Development of Sinus Venosus
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Development of Sinus Venosus
The remains of left sinus horn oblique vein of
left atrium coronary sinus
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Formation of Ventricular Septum
1. Growth of Endocardial cushions
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Septum Formation in A-V Canal
1. Endocardial cushions appear. 2. AV canal
enlarges to the right. 3. Fusion of sup. inf.
Endocardial cushions (10 mm. stage) 4. Rt. Lt.
AV orifices are formed.
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Formation of Ventricular Septum
2. Growth of ventricular wall to form Muscular
ventricular septum
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1. Medial wall of ventricles form muscular
intervent. septum 2. Outgrowth of inf. EC to
close interventricular foramen. ( membranous
interventricular septum)
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Formation of Ventricular Septum
3. Growth of Trunco-conal ridges fusion with
endocardial cushion
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Formation of Ventricular Septum
3. Growth of Trunco-conal ridges fusion with
endocardial cushion
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Septum Formation in Truncus Conus
Fusion of Rt. Lt. conus swelling outflow
tracts of Rt. Lt. ventricle.
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Formation of Cardiac valves
1. Aortic valves Pulmonary valves (Semilunar
valves)
6 wk.
5 wk.
7 wk.
6 wk.
7 wk.
9 wk.
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Formation of Cardiac valves
2. Mitral valves Tricuspid valves
(Atrioventricular Valves)
1. Proliferation of mesenchyme in A-V orifice. 2.
The cords becomes hollowed out by bloodstream. 3.
The muscular tissue degenerates, replaced by
dense CNT. 4. A-V valves CNT covered by
endocardium connected to papillary muscles by
chordae tendineae. 5. Right tricuspid valves
Left bicuspid (Mitral) valves
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Arterial System
4 wk (4 mm.)
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Fate of Truncus Arteriosus Aortic Sac
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Fate of Aortic Arches
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Fate of Aortic Arches
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Aortic arches
4 mm. I disappear rem. Maxillary a. II
disappear rem. Hyoid a. Stapidial a. III,
IV VI become larger. Primitive pulmonary a.
is formed.
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Aortic arches
10 mm. I II disappear VI connect to
Pulmonary trunk
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Transformation to Adult Arterial System
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Transformation to Adult Arterial System
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Transformation to Adult Arterial System
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Other Changes in the Arch System
1
4
2
3
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Other Changes in the Arch System
1. Obturation of Carotid duct (Dorsal aorta
between III IV) 2. Obturation of Rt. dorsal
aorta (at 7th intersegmental a.) 3. Lt.
subclavian a. shifts to higher point. 4.
Recurrent laryngeal n.
Rt hook at Subclavian a.
Lt hook at Ligamentum arteriosum
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Derivatives of Dorsal Aorta

• Intersegmental a.
• supply ribs, intercostal m. spinal cord
• C L segments - supply limbs
• Lateral splanchnic a.
• supply kidneys gonads (intermediate mesoderm)

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Derivatives of Dorsal Aorta

• Ventral splanchnic a.
• With yolk sac
• Vitelline a. supply yolk sac
• Umbilical a. supply placenta developing
  visceral organ
• Without yolk sac
• Celiac a. supply foregut eg stomach
• Sup. mesenteric a. supply midgut eg.
  duodenum ileum
• Inf. Mesenteric a. supply hind gut eg.
  colon rectum

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Vitelline and Umbilical Arteries
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Venous System
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Venous System

• 1. Vitelline veins
• 2. Umbilical veins
• 3. Common cardinal veins
• Anterior cardinal veins
• Posterior cardinal veins

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Vitelline veins
1. LVV are converted into Hepatic sinusoids,
Hepatic v. and Portal v. 2. RVV persists as IVC
(post-hepatic IVC)
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Vitelline veins
4 - 5 wk
4 wk form plexus to duodenum septum
transversum 5 wk form hepatic sinusoid
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Vitelline Veins
8 - 12 wk
8 wk Rt. hepatocardiac channel enlarges 12
wk RVV is converted into IVC (hepatic portion)
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Umbilical veins
1. Differentiation into Hepatic sinusoids 2. LUV
Ductus arteriosus form Ligamentum
arteriosum 3. RUV degenerates 4. LUV (caudal)
persists in fetal life
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Umbilical veins
4 - 5 wk
5 wk RUV LUV connect to Hepatic sinusoid
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Umbilical Veins
8 - 12 wk
Ductus venosus is formed. Lt. umbilical vein
enlarges.
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Anterior Cardinal Veins
1
2
3
1. Anastomosis of ACV shunts blood from LACV to
RACV form Left Brachiocephalic v. 2.
LACV(caudal) degenerates. 3. RACV RCCV form
SVC
7 wk.
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Posterior Cardinal Veins
1. Degenerate with the development of metanephric
kidney 2. Persists as common iliac v. Root of
Azygos v. 3. Two temporary venous system
develop a.) Subcardinal v. develops into LRV,
Gonadal v., Suprarenal v., IVC (hepatic
segment) b) Supracardinal vein develops
into Azygos v. Hemiazygos v. IVC (lower)
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Fate of Fetal Circulatory Structures
1. Umbilical vein
Ligamentum teres hepatis
2. Ductus venosus
Ligamentum venosum
3. Umbilical artery
Medial umbilical ligament
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Fetal Circulation
High oxygen content decreased in I Liver II
IVC III Rt. atrium IV Lt. atrium V Desc.
Aorta (at the entrance of ductus arteriosus)
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Changes at Birth
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• Causes
• cessation of placental blood flow
• lung respiration

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Changes 1. Closure of umbilical a. formation
of med. umbilical lig. 2. Closure of UV ductus
venosus formation of lig. teres lig.
venosum 3. Closure of ductus arteriosus by
bradykinin formation of lig. arteriosum 4.
Closure of oval foramen
2
1
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Lymphatic System
5 wk. origin mesenchyme or out growth of
endothelium of veins 6 primary lymph sacs are
formed - 2 jugular lymph sacs - 2 iliac
lymph sacs - 1 retroperitoneal lymph sac
- 1 cisterna chyli
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Lymphatic System

• Rt. LT. Lymphatic ducts
• Rt. Lt. thoracic ducts

• Thoracic duct
• Rt. lymphatic duct

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Formation of Conducting System
1. Pacemaker lies in - initially left
cardiac tube - later sinus venosus
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Formation of Conducting System
2. Incorporation of sinus into Rt. atrium. 3.
Sinuatrial node is formed.
4. A-V node Bundle of His are derived from
cells of a. left wall of sinus venosus (base
of interatrial septum) b. A-V canal
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Abnormalities of Heart Position
Dextrocardia cardiac loop to the left. Heart
in the right thorax associated with situs
inversus (transposition of the viscera)
Ectopia cordis Heart on the surface of chest
caused by failure to close the midline
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Common Congenital Anomalies
Etiologic factors 1. Disorders of chromosome
numbers eg. trisomy 21, 18 or 13 2. Familial
disorders 3. Teratogenic viral infections
Rubella
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Atrial Septal Defects (ASD)

• Probe patency of Foramen ovale
• Left to right shunt of blood

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Atrial Septal Defects (ASD)
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Ventricular Septal Defect

• 1 in 500
• Trisomy syndrome
• 90 involve Membranous interventricular septum
• Shunted from left to right ventricle

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Ventricular Septal Defects
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Tetralogy of Fallot

• 1 in 8500
• Four anomalies
• 1. Ventricular septal defect
• 2. Pulmonary artery stenosis
• 3. Overiding aorta
• 4. Right ventricle hypertrophy

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Tetralogy of Fallot
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Tricuspid Atresia

• 1 in 5000
• Fusion of tricuspid valves
• Patent oval foramen
• Ventricular septal defect
• Right ventricle atrophy
• Left ventricle hypertrophy

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Tricuspid Atresia
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Patent Ductus Arteriosus

• 1 in 3500
• Shunting oxygenated blood to pulmonary artery
• Prostaglandin synthetase inhibitors eg.
  indomethacin can promote closure of Ductus
  arteriosus

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Patent Ductus Arteriosus
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Abnormalities of Semilunar Valves
1. Transposition of great vessels
2. Pulmonary valvular stenosis
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Abnormalities of Semilunar Valves
4. Aortic valvular atresia
3. Aortic valvular stenosis
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Abnormalities of Great Vessels
1. Patent ductus arteriosus 2. Preductal
Postductal coarctation of aorta
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Abnormalities of Great Vessels
3. Abnormal origin of Right subclavian a. 4.
Double aortic arch
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Abnormalities of Great Vessels
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Abnormalities of Venous Drainage
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Abnormalities of Venous Drainage