CARDIOVASCULAR
DEVELOPMENT
• Cardiovascular system is composed of:
– Cells (red and white).
– Vessels (arteries, veins and lymphatic's).
– Pump (heart).
CARDIOVASCULAR
DEVELOPMENT
• Heart begins to develop in middle of 3rd
week because diffusion won’t supply
adequate nutrition.
• Mesenchymal cells from visceral
mesoderm form angiogenitic cells
which give rise to blood vessels.
ANGIOGENESIS
CARDIOVASCULAR
DEVELOPMENT
• At the dorsal region of the embryo, 2
vascular tubes form: the dorsal aortae.
• At the ventral region of the embryo, 2
vascular tubes form: the heart tubes.
• The 2 heart tubes fuse together into a single
heart tube and it occupies a pericardial
cavity.
FUSION OF HEART TUBES
FORMATION OF HEART WALL
CARDIOVASCULAR
DEVELOPMENT
• Rapid brain growth moves the heart to a ventral and caudad position.
• Because of space restriction, and rapid rate of heart tube growth, the
tube folds on itself.
• Folding results in base of heart being cephalad and apex being
caudad.
• The septum transversum forms between the heart cavity and the
abdominal cavity and will become the respiratory diaphragm.
• Heart is usually located on left side unless dextrocardia occurs.
CARDIOVASCULAR
DEVELOPMENT
• At 4 weeks primitive circulation is present.
• Aortic arches are forming arteries in the head
(pharyngeal pouches).
• Dorsal aorta is present.
• Major veins are present:
– 1. Vitelline veins draining yolk sac.
– 2. Common cardinal veins drain body.
– 3. Umbilical veins bring blood from primitive placenta to
embryo.
CARDIOVASCULAR
DEVELOPMENT
• The pharyngeal apparatus consists of:
– 1. Arches
– 2. Clefts
– 3. Pouches
– The pharyngeal apparatus forms structures in head and neck and each
arch has a nerve artery and vein.
– Six aortic arches are present in the human embryo.
– The arches arise ventrally from the truncus arteriosis (aortic sac) and join
the dorsal aorta.
– Arches 3, 4 and 6 persist in humans to become major arteries in the head
and neck.
–
PHARYNGEAL ARCHES CLEFTS AND
POUCHES
PERSISTING ARCHES 3,4 AND 6.
CARDIOVASCULAR
DEVELOPMENT
• Fate of the pharyngeal arches:
– #3 arch gives rise to common carotid aa.
– #4 arch gives rise to aortic arch and right
subclavian artery.
– #6 arch gives rise to pulmonary artery and ductus
arteriosus.
– #’s 1,2 and 5 arches are obliterated and disappear.
DIVIDING HEART INTO RIGHT AND LEFT
ATRIA (SEPTATION).
• Right and Left atria are separated by primary and
secondary embryonic walls (septa).
• A prenatal “valve” is composed of the lower portion
of primary septa and upper portion of the secondary
septa.
• Valve is named “foramen ovale” which closes at
birth and becomes the “fossa ovale”.
• Foramen ovale allows blood to “by-pass” fetal lungs.
DIVIDING HEART INTO LEFT
AND RIGHT VENTRICLES.
• The ventricles are divided by septa of 2
different tissue types:
– The upper intramembranous septa.
– The lower intramuscular septa.
– The endocardial cushion tissue plays a major role
in development of septa and valves of heart.
CARDIAC SEPTAL DEFECTS
• Intra-atrial septal defects occur when primary
and secondary atrial septa fail to form
correctly.
• Approxamately 20% of adults have “ probe
patent foramen ovale”.
• The most common congenital cardiac
malformation is ventricular intramembranous
septal defect.