The document describes the process of vasculogenesis and angiogenesis in embryonic development. Vasculogenesis is the formation of new blood vessels from mesodermal blood islands, involving the differentiation of hemangioblasts into endothelial cells and blood cells. Angiogenesis is the formation of new vessels from existing ones. It also discusses the development of the heart, including the formation of the atrial and ventricular septa by fusion of endocardial cushions. The fetal circulatory system is described, which involves blood shunting from the right atrium to left via the foramen ovale and ductus venosus/arteriosus, allowing most blood to bypass the lungs. After birth, these fetal circulatory

2. Vasculogenesis
• It is the process of formation of new vessels
from blood islands

3. Process of vasculogenesis
• At 3rd week of development
• In the wall of yolk sac
• Blood islands are produce from mesoderm
• Process
• Mesodermal cells produce blood islands
• Mesodermal cells are converted into hemangioblast by
fibroblast growth factor 2 (FGF 2)

4. Process of vasculogenesis
• Hemangioblast are a common precursor for veesel and
blood cell formation
• Hemangioblast of center of blood islands form
hematopoietic stem cells , the precursor of all blood cells
• The peripheral hemangioblast differentiate into
angioblasts , the precursor of blood vessels
• Angioblast is converted into endothelial cells by VEGF
secreted by surrounding mesoderm cells

10. Angiogenesis
• it is the process of formation of new
vessels by budding and branching from
pre-existing vessels

12. Thank you

13. Development of arterial system
• Aortic arch arteries
• Dorsal aorta

17. The aortic arches or pharyngeal arch arteries
• They are a series of
six paired
embryological
vascular structures
which give rise to
several major
arteries. They are
ventral to the
dorsal aorta and
arise from the
aortic sac.

18. Aortic arches
Arch Arterial component
1 Maxillary arteries
2 Hyoid and stapedial artery
3 Common carotid and 1st part of the internal
carotid artery
4 Right side : right subclavian a
Left side: arch of aorta from the left common
carotid to the left subclavian artery
6 Right side : right pulmonary artery
Left side: left pulmonary artery and ductus
arteriosus

19. Artery arises from dorsal aorta
Embryonic structure Adult derivatives
Posterolateral
(intersegmental ) branches
Arteries of upper and lower limbs,
Intercostal , lumbar and lateral sacral
arteries
Lateral splanchnic branches Phrenic arteries , suprarenal arteries
, renal arteries , gonadal arteries
Ventral splanchnin branches
Vitelline arteries Celiac artery , superior mesenteric
artery , inferior mesenteric artery
Umbilical arteries Superior vesical artery

20. Axial Artery of upper and lower limb
Embryonic structure Adult derivatives
7th cervical intersegmental
artery is the axis artery of
upper limb
Main trunk of axis artery forms axillary
artery, brachial artery, part of radial
artery, anterior interosseous artery and
deep palmar arch
5th lumbar intersegmental
artery
Inferior gluteal artery , popliteal artery
above popliteus , lower part of
peroneal artery, some parts of plantar
arch

21. • Development of heart tube

26. Pulmonary trunk:
Rt ½ of truncus arteriosus
Rt ventricle
Outflowing smooth part:
rt ½ of bulbus cordis
Inflowing rough part:
rt ½ of primitive ventricle
Rt atrium
Anterior rough part:
Rt ½ of primitive atrium
Posterior smooth part :
rt horn of sinus venosus
Right side Left side

27. Aorta:
Lt ½ of truncus arteriosus
Lt ventricle
Outflowing smooth part:
Lt ½ of bulbus cordis
Inflowing rough part:
Lt ½ of primitive ventricle
Lt atrium
Anterior rough part:
Lt ½ of primitive atrium
Posterior smooth part:
absorbed proximal parts of
the pulmonary veins
Right side Left side
Lt sinus venosus develop
coronary sinus & oblique
vein of left atrium

28. Development of left atrium
•Rough part of left atrium is developed
from Left half of the primitive atria
•Smooth part of left atria is developed
from absorbed proximal parts of the
pulmonary veins
Development of Coronary sinus &
oblique vein of left atrium
is developed from left horn of sinus
venosus

29. Development of inter-ventricular septum

30. Thick muscular part developed from floor of ventricular
wall

31. Formation of bulbar septum
The bulbar septum is formed by fusion of right & left
bulbar ridges

32. Development of interventricular septum
So Thin membranous
part:
developed from
• bulbar septum and
• Gap between bulbar
septum & muscular
part is filled by
anterior & posterior
endocardial cushions

34. Congenital anomalies
• Ventricular septal defects are the most
common congenital heart disease

35. Development of inter-atrial septum

36. The septum primum,
a sickle shaped crest descending
from the roof of the atrium begins
to divide the atrium in two.
But leaves a lumen the
ostium primum for
communication between two sides
of atria

37. • Later when ostium primum is
obliterated by fusion of the
septum primum with the
endocardial cushions the
ostium secundum is
formed in the septum
primum

38. • Septum secundum
arises from the roof
of the atrial
chamber . It grows
downward and
overlapped the
foramen secundum

39. • Now the right
and left atrium
communicate
with foramen
ovale, a oblique
valvular opening

40. After birth the
pressure of left
atrium increases so
foramen ovale is
closed

42. Venous system of fetus
• Sinus venosus has three tributaries
1. Cardinal vein
2. Vitelline vein
3. Umbilical vein

43. • Arteries and veins of fetus

45. Venous system of fetus
1. Vitelline system : develops portal
system
2. Umbilical system : which disappear
after birth
3. Cardinal system : forms caval system

46. Venous system of fetus

49. Fetal circulation
1. Most of the blood of
Right atrium > foramen ovale
Left atrium > left ventricle >
aorta
2. Less amount of blood of
Right atrium> right ventricle >
pulmonary trunk > lungs >
pulmonary vein > left atrium >
left ventricle > aorta

50. Fetal circulation
1. Most of the blood of
Aorta > systemic circulation
>umbilical arteries > placenta
umbilical vein > ductus
venosus > IVC > right atrium
2. Less amount of blood of
Aorta > systemic circulation
>umbilical arteries > placenta
> umbilical vein > liver > IVC >
right atrium

53. So after birth
• 5 structures close
• Closure of umbilical artery and vein : 2
• Closure of ductus arteriosus and venosus : 2
• closure of foramen ovale : 1

54. Fate of following structures after birth
• two umbilical arteries is converted into superior vesical artery and
medial umbilical ligament
• two umbilical veins,
• The right umbilical vein degenerates and the left umbilical vein
becomes the ligamentum teres around the liver
• Ductus arteriosus is converted into ligamentum arteriosum
• Ductus venosus is converted into ligamentum venosum
• foramen ovale usually obliterated but sometimes patent (open)

55. • Thank you