Download L9 Heart and bloodvessels

The endoderm folds to become
the gut tube and the body sides
form to enclose body cavities
8 day mouse, transverse
N
So
S
Sp
E
N Neural tube
S Somite
So Lateral mesoderm (somatopleure)
Sp Lateral mesoderm (splanchnopleure)
E Gut tube
9 day mouse, transverse
A
A
G
C
So
Sp
A Split aorta
G Gut tube
So Somatopleure, parietal mesoderm*
Sp Splanchnopleure, visceral mesoderm*
C Cavity
* Collectively a serous membrane around
the body cavity
http://www.med.unc.edu/embryo_images/
The pleuropericardial cavity divides
and the cavities are lined by parietal and visceral surfaces
Aorta
Oesophagus
Lungs
Peripleural
cavity
Heart
Pericardial
cavity
Parietal surface of pleural and pericardial cavities
Visceral surface of pleural and pericardial cavities
Form a single serous
membrane sac around
the cavity
The peritoneal cavity is subdivided laterally at the rostral end
but is a single cavity at the caudal end
Aorta
Pancreas
Dorsal mesentery
Stomach
Small intestine
Liver
Ventral mesentery
Parietal surface of peritoneal cavity
Visceral surface of peritoneal cavity
Form a single serous
membrane sac around
the cavity
DEVELOPMENT OF THE HEART AND GREAT BLOOD VESSELS
LEARNING OUTCOMES
1. explain the early development of the heart from splanchnic mesoderm ahead of the neural
plate which is then folded beneath the pharynx of the head fold.
2. outline the fusion of the endocardial tubes to form the simple linear heart with atrium, ventricle
and valvular flaps pumping blood into the aortic arches.
3. define the three circulatory arcs of the heart supplying the body tissues, the yolk sac (vitelline)
and the allantois and describe their functions
4. describe the role of the yolk sac splanchnopleure in early haematopoiesis
5. Understand the developmental process by which the aortic arches and truncus arteriosis are
adapted to give the aortic and pulmonary trunks and the carotids
6. Show how septum formation in the primitive linear heart allows separate pumping of blood into
the aorta and the pulmonary trunk
7. describe the congenital abnormalities of septal defects, patent ductus arteriosus, and
persistent aortic arch
FORMATION OF THE MAMMALIAN GASTRULA - 9
MESODERM
TYPE
INTERMEDIATE
STRUCTURE
HEAD
CHORDA-
MESODERM
DERIVATIVE
HEAD MUSCLES, SKULL,
CARTILAGE
NOTOCHORD
LIMB MUSCLES
AXIAL SKELETON
PARAXIAL
ICM
EPIBLAST
SOMITES
MESODERM
TRUNK MUSCLES
DERMIS
INTERMEDIATE
PARTS OF KIDNEY
AND REPRODUCTIVE TRACT
LIMB SKELETON
HEART
LATERAL
BODY CAVITY DIVIDERS
BLOOD CELLS
AMNION
CHORION
YOLK SAC
ALLANTOIS
* epithelial part
only of organ
Lungs*
Thyroid*
Liver*
Pancreas*
Middle
Ear*
Tonsils*
Gut
tube*
Allantois*
Bladder*
Parathyroid*
Sclerotome
Gonads*
Lateral
mesoderm
Intermediate
mesoderm
Olfactory
epithelium
Stomodeal
epithelium
ECTODERM
Head
mesoderm
Notochord
Neural
tube
Skull
Branchial
cartilage
Oral
epithelium
THE MAP
OF ORIGINS
Teeth
enamel
Anterior
pituitary
Brain
Spinal
cord
Eye
Somatic mesoderm
Extraembryonic
Kidney and
Neural
Parietal pleura,
mesoderm of yolk
reproductive
Axial
crest
pericardium,
sac and allantois
tracts
skeleton
Dermatome
peritoneum
Extraembryonic
Blood
mesoderm of
Visceral pleura
Dermis
cells
amnion
and
chorion
Visceral
peritoneum
Trunk
Splanchnic
Mesenteries
Muscles
mesoderm
Teeth
Appendicular
dentine
muscles
Connective tissue,
Heart
Sympathetic
smooth muscle
ganglia
of viscera and
Vascular
blood vessels
endothelium
Melanocytes
Myotome
Primary
germ cells
Paraxial
mesoderm
Anal
canal
Surface
epithelium
ENDODERM
MESODERM
Hair,
nails
Mammary
glands
EPIBLAST
Pharynx
Pharyngeal
pouches
INNER CELL
MASS
Extraembryonic
endoderm of yolk
sac and allantois
Sweat
glands
Cranial
motor
nerves
Spinal
motor
nerves
Cranial
sensory
nerves
Adrenal
medulla
Spinal
sensory
nerves
The cardiac tube folds under the gut tube……
THE EARLY DEVELOPMENT OF THE HEART - 1
B
A
DORSAL AORTA
GUT TUBE
ENDODERM
CARDIAC TUBE
PERICARDIAL CAVITY
VITELLINE VEINS
CARDIAC PRIMORDIUM
(SPLANCHNIC MESODERM)
The cardiac primordia are established in
the early gastrula as regions of splanchnic
mesoderm ahead of the embryo itself. As a
result of the head fold, this region ends up
beneath the pharynx.
The heart is a U-shaped tube at this stage and
the forming blood vessels are initially
unconnected
……and connects bilaterally with the dorsal aorta via the aortic arches
C
FUSED DORSAL AORTA
1ST AORTIC ARCH (R)
VENTRICLE
ORAL PLATE
The sides of the U-tube then fuse to
produce the atrial and ventricle regions
with valvular flaps to prevent back flow so
that the heart can function as a simple
peristaltic pump.
ATRIUM
VENOUS RETURN FROM
CARDINAL VEINS,
VITELLINE VEIN AND
ALLANTOIC (UMBILICAL)
VEIN
The dorsal aorta form independently and
then grow to meet the ventral output from the
heart in the aortic arches
This pattern of mammalian development
is a good example of recapitulation
D
PHARYNGEAL POUCHES
LUNG BUD
THIS STAGE RESEMBLES FISH
The diagram shows 6 aortic arches but, in mammals, 1 and
2 are regressing while the later arches are forming and
arches 5 never form
REMINDER:
The branchial arches and clefts and the juxtaposed pharyngeal
pouches are a recapitulation of the respiratory anatomy of fish
Mouse, 8 day, sagittal
Mouse, 9 day, frontal
Mouse, 10 day, frontal
The heart twists
so that the
atrium is rostral
to the ventricle
Mouse, 8 day, frontal
The heart folds under the pharynx
Mouse, 9 day, side
http://www.med.unc.edu/embryo_images/
The embryonic circulation has three circulatory arcs
through which blood is pumped by a simple linear heart
Dorsal aorta
Cardinal veins
Mesonephros
Aortic arches
Vitelline vein
Vitelline artery
Allantoic artery
Allantoic vein
Deoxygenated blood
Mixed blood
Oxygenated blood
Yolk sac
Chorio-allantoic
placenta
THE CIRCULATORY ARCS OF THE EMBRYONIC BLOOD SUPPLY
1.
BODY CIRCULATION
TRANSPORT OF O2 /FOOD MATERIALS TO TISSUES
TRANSPORT OF WASTE MATERIALS AWAY
2.
VITELLINE CIRCULATION
CARRIES MOBILISED FOOD MATERIALS FROM THE YOLK SAC
LOST FUNCTION IN MAMMALS BECAUSE SAC EMPTY
CARRIES FIRST BLOOD CELLS FROM YOLK SAC
SPLANCHNOPLEURE
3.
ALLANTOIC CIRCULATION
IN MAMMALS TAKES OVER THE FUNCTIONS OF THE
VITELLINE ARC IN BIRDS
SUPPLIES FOOD MATERIALS FROM MATERNAL
CIRCULATION
RETAINS AVIAN FUNCTION OF REMOVAL OF WASTE
AND GAS EXCHANGE
MESENCHYME IN
SPLANCHNOPLEURE
OF YOLK SAC
Haematopoiesis begins in the
splanchnopleure of the yolk sac
before transferring to the embryo
itself later in development
CELL CLUSTERS
ENDOTHELIAL CELLS
HAEMATOPOIETIC
CELLS
ENDOTHELIUM
BLOOD ISLAND
FORMATION OF BLOOD
VESSEL
From Noden and La Hunta p 211
AGGREGATION OF FURTHER
MESENCHYME TO FORM
MUSCULAR AND CONNECTIVE
TISSUE WALL
The simple tubular heart twists to prepare for septum formation and the creation of a fourchambered organ. The aortic arches are selectively modifed to give rise to the great arteries
THE HEART AND THE AORTIC ARCHES - FORMATION OF THE GREAT BLOOD VESSELS
CAROTIDS
(from L and RIII)
AORTA
(from LIV)
I
II
III
IV
V
VI
III
IV
VI
TA
A
RIGHT
SUBCLAVIAN
(from RIV)
DUCTUS
ARTERIOSUS
(LVI to LIV)
RA
LA
PULMONARY
TRUNK
(from LVI)
SEPTA
A
V
V
LV
RV
VENOUS RETURN
NOTES:
1. View from ventral surface
2. RA - Right atrium, LA - Left atrium, RV - right ventricle,
LV - left ventricle, TA = truncus arteriosus
After birth venous return is from
vena cava (blue arrows) and
pulmonary veins (red arrows)
The separation between atria and between ventricles and between
atria and ventricles occurs by means of septum formation
SEPTUM FORMATION
Vena cava
ATRIAL
SEPTATION
Pulmonary
veins
A
Foramen
ovale
Vena cava
ATRIOVENTRICULAR
SEPTATION
VENTRICULAR
SEPTATION
V
RV
LV
PRIOR TO SEPTATION
(SURFACE VIEW )
INCOMPLETE SEPTATION
(SECTION)
A
Mouse, 12 days,
section of truncus arteriosus
Mouse, 10 days, frontal section
Blood from the atrium passes
to the ventricle by means of a
channel. The beginnings of
interatrial septum formation
can be seen (A)
Cushions form within the truncus
arteriosus and will fuse to form
the aortico-pulmonary septum
separating the aortic and
pulmonary flows
http://www.med.unc.edu/embryo_images/
FOETAL CIRCULATION
25
Brachycephalic vessels
14
To
lungs
19
DA
From lungs
FO
25
19
25
14 Liver
30
22
Trunk
Placenta
Hindlimb
There is a split between deoxygenated
blood returning from the rostral end of
the foetus and oxygenated blood
returning from the placenta. This spit
is achieved by directed flow through
the foramen ovale
CHANGES IN THE CIRCULATION AT BIRTH
• Contraction of allantoic artery and veins to force placental blood
into main circulation. Rupture of umbilical cord
• Contraction of Ductus arteriosus and closure of Foramen ovale so that
right side blood is directed to lungs
DEFECTIVE SEPTUM FORMATION
INTER-ATRIAL SEPTAL DEFECT
(persistent Foramen ovale)
INTER-VENTRICULAR SEPTAL DEFECT
(Tetralogy of Fallot is variation on this)
PERSISTENCE OF AORTIC ARCHES AND VASCULAR RING ANOMALIES
Right 4
Left 6
Oesophagus
PATENT DUCTUS
ARTERIOSUS
PERSISTENT RIGHT AORTIC
ARCH IV
REFERENCES
Carlson BM (2003) Patten's Foundations of Embryology
Noden DM, de Lahunta (1985) A Embryology of domestic animals
McGeady TA, Quinn PJ, Fitzpatrick ES, Ryan MT (2006) Veterinary embryology
University of North Carolina web site: http://www.med.unc.edu/embryo_images/