3 rd week axial › prechordal mesenchyme › cardiogenic › septum transversum paraxial ...
TRANSCRIPT
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BODY CAVITIES
DR. ZAHRA HAIDER BOKHARI
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EXTRA-EMBRYONIC COELOM
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MESODERM
3RD WEEK
AXIAL
› Prechordal
mesenchyme
› Cardiogenic
› Septum transversum
PARAXIAL
INTERMEDIATE
LATERAL PLATE
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INTRAEMBRYONIC COELOM
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INTRA-EMBRYONIC COELOM
4th wk.
Inverted U shaped cavity in:
› Cardiogenic area
› Lateral plate mesoderm
Bend –cranial to prochordal
plate – primitive pericardial
cavity
Limbs of U – lateral half of disc
Limbs :
› Pleural cavity
› Peritoneal cavity
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INTRA-EMBRYONIC COELOM
Initial part of limbs – flank
foregut
Caudal part of limbs –
communicate with extra-
embryonic coelom
The two limbs are called
pericarioperitoneal canals
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FOLDING
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HEAD FOLDING
4th week
Pericardial cavity – ventral -
below foregut
Pericardial cavity bend at right
angle – communicate with
pericardioperitoneal canal
Pericardioperitoneal canal
› Dorsal to septum transversum
› Lateral to foregut
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TRANSVERSE FOLDING
Pleuroperitoneal
canals –
Ventral aspect
Merge – single
peritoneal cavity
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The coelome lined by
mesothelium
Derived from:
Somatic mesoderm (parietal
layer)
Splanchnic mesoderm
(visceral layer)
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DIVISION OF INTRA-EMBRYONIC COELOM
Into:
› Pericardial cavity
› Pleural cavity
› Peritoneal cavity
Division achieved by:
› Septum transversum
› Paired pleuropericardial folds – superior to lungs
› Paired pleuroperitoneal folds – inferior to lungs
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PLEUROPERICARDIAL MEMBRANE
4th week
Bronchial buds-
pericardioperitoneal
canal – future pericardial
cavity
Pleural cavity expand –
grow ventrally
Common cardinal vein &
Phrenic nerve raise
ridge in lateral thoracic
wall
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PLEUROPERICARDIAL MEMBRANE
Pleural cavity grow in
angle between body wall
& ridge
Result:
› Mesenchyme of body
wall split
Outer layer – thoracic
wall
Inner layer –
pleuropericardial
membrane
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PLEUROPERICARDIAL MEMBRANE
7th week
membrane – grow medially
Pleuropericardial – fuse with
› Each other
› Mesenchyme ventral to
oesophagus
Separate pericardial from pleural
cavity
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PLEUROPERICARDIAL MEMBRANE
Right pleuropericardial
opening close earlier
› Right common cardinal
vein larger – raise bigger
fold
Fused pleuropericardial
membrane form FIBROUS
PERICARDIUM
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PLEUROPERITONEAL MEMBRANE
Separate pleural from peritoneal
cavity
Lung & pleura invade body wall –
strip mesoderm
Ridge formed – caudal end of
pericardioperitoneal canal
Ridge- fold –cresentic free edge-
project into pericardioperitoneal
canal
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PLEUROPERITONEAL MEMBRANE
Liver develop
Fold become membranous
6th week
Pleuroperitoneal
membrane grow ventro –
medially - fuse with:
› Dorsal mesentry of
oesophagus
› Septum transversum
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MESENTERY
Double layer of peritoneum
enclosing a mass of mesoderm
Connects the organ to the body
wall
Carries vessels, nerves &
lymphatics for the organ
Is the site where the visceral
peritoneum continues as parietal
peritoneum
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MESENTRY
Transverse folding –medial walls
of intra-embryonic coelon come
together – mesentry
Between layers – mesenchyme –
B.V. & nerves
Transiently divide I.E.Coelom into
two halves
Contain gut in them
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VENTRAL MESENTRY
Transitory structure
Limited to stomach & duodenum
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DORSAL MESENTRY
Gut suspended by it – mid plane
Not in pharynx & upper
oesophagus
Given names– mesoesophagus….
Further development
› Some parts specialized
› Some – secondary attachment
› Some disappear
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DEVELOPMENT OF PERICARDIUM
Heart tube invaginate
pericardium from dorsal aspect
Parietal & fibrous pericardium
derived from somatopleuric
mesoderm lining ventral side of
pericardial cavity
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DORSAL MESOCARDIUM
Visceral pericardium derived from
splanchnopleuric mesoderm lining
dorsal side of pericardium
Heart tube suspended in
pericardial cavity by dorsal
mesocardium - disappears
Communication – right & left side
of pericardium – transverse
pericardial sinus
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DORSAL MESOCARDIUM
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DEVELOPMENT OF DIAPHRAGM
Four sources
1. Septum transversum
2. Pleuroperitoneal
membranes
3. Dorsal mesentery of
esophagus
4. Muscular ingrowth from
lateral body walls
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SEPTUM TRANSVERSUM
3rd week
› Unsplit mesoderm
› Cranial to cardiogenic mesoderm
4th week
› Folding
Septum transversum
Caudal to pericardium
Ventral to pericardio-
peritoneal canal
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SEPTUM TRANSVERSUM
Cranial part - diaphragm
Caudal part
› Liver
› Ventral Mesentry
Expand & fuse with
pleuroperitoneal
membrane
Form central tendon
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PLEUROPERITONEAL MEMBRANE
5th week
Develop at caudal end of
pericardioperitoneal canal
Crescent fold - medially
Fuse with:
› Septum transversum
› Dorsal mesentry oesophagus
Myoblast from S.T. –
pleuroperitoneal membrane
Bulk of muscle form here
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DORSAL MESENTERY OF ESOPHAGUS
Initially – median part
Finally mesoesophagus
condenses – L1 – L3
Two muscle bands
› Myoblast grow in dorsal
mesentry of esophagus
Develop into Right &
left crura
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CONTRIBUTION FROM BODY WALL
9th – 12th week
Lungs & pleural cavity
enlarge
Burrow into body wall
Mesenchyme split
› External – abdominal wall
› Internal – peripheral part of
diaphragm
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CONTRIBUTION FROM BODY WALL
Pleura extend further
› Costodiapharagmatic
recess
› Dome shaped
configuration
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DIAPHRAGM
6th week :
Three basic components:
1. Pleuroperitoneal
membranes
2. Mesoesphagus
3. Septum transversum
Fuse - form a complete
partition between thoracic
and abdominal cavities
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Body wall:
Peripheral muscular part
Pleuroperitoneal membranes:
Form large portion of fetal
diaphragm
represent a smaller portion in
infants
Septum transversum:
Central tendon
Dorsal mesentery of esophagus:
Crura
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POSITIONAL CHANGES & INNERVATION OF THE DIAPHRAGM
• 4th week
• Septum transversum opposite 3rd – 5th
cervical somites
• 5th week
• Myoblasts from somites - developing
diaphragm bringing their nerve fibers
with them
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• Rapid growth of the body -
descent of diaphragm
• 6th week the diaphragm -
level of the thoracic
somites
• End of 8th week -
diaphragm - level of first
lumbar vertebra
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4 parts of the diaphragm fuse
Mesenchymal cells from the septum
transversum - other three parts,
Change into myoblasts -muscles of
the diaphragm.
Phrenic nerve supplies all the
muscles of diaphragm
Phrenic nerve - sensory to
diaphram except peripheral region
derived from the body wall and brings
its nerve supply (lower intercostal
nerves) with it
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POSTEROLATERAL DEFECTS OF DIAPHRAGM
Only common anomaly
1 in 2200 newborns
Associated with CDH
Inhibition of development & inflation of lung- breathing difficulties
Lung hypoplasia – infant may die
Severe lung hypoplasia – alveoli rupture – pneumothorax
Polyhydramnios maybe present
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POSTEROLATERAL DEFECT OF DIAPHRAGM
Cause:
› Defective formation / fusion of
pleuroperitoneal membrane with...
Large opening in posterolateral
part of diaphragm
Peritoneal & pleural cavities
communicate
85-90% on left side – foramen of
Bochdalek
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POSTEROLATERAL DEFECTS OF DIAPHRAGM
Foramen closes at 6th wk.
If open –viscera in thorax – lying
Lungs & heart pushed anteriorly
Most defects on left side – heart
pushed to right
Severity of lung development –
extent of viscera in thorax – no
room for development
Treatment
› Repair of defect – post natally
› Lung achieve normal size
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EVENTRATION OF DIAPHRAGM
Half of diaphragm – defective
musculature – diaphragmatic pouch
Superior displacement of viscera
Cause:
› Failure of muscular tissue from body
wall to extend into pleuroperitoneal
membrane
Clinical manifestation – CDH
Treatment:
› Surgical repair
Latissimus dorsi flap
Prosthetic patch
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GASTROSCISIS & CONGENITAL EPIGASTRIC HERNIA
Herina – between
xiphoid process &
umbilicus
Cause:
› Failure of lateral body
folds to fuse completely
when forming anterior
abdominal wall during
folding
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CONGENITAL HIATAL HERNIA
Herniation of part of fetal
stomach through excessively
large esophageal hiatus
May be a predisposing factor
in adult acquired hiatal hernia
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RETROSTERNAL (PARASTERNAL) HERNIA
Herniation through the sternocostal hiatus (foramen of Morgagni) – opening
for superior epigastric B.V.
Hiatus – between sternal & costal parts of diaphragm
Herniation of:
› Intestines into pericardial sac
› Heart into peritoneal cavity
Large defects associated with body wall defects
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ACCESSORY DIAPHRAGM
Most often on right side
Associated with lung hypoplasia & respiratory comlications
Diagnosis:
› MRI
Treatment:
› Surgical excision
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A
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B
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C
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D
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E
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F
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G
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mesentry
Double layer of peritoneum enclosing a mass of mesoderm
Connects the organ to the body wall
Carries vessels, nerves & lymphatics for the organ
Is the site where the visceral peritoneum continues as parietal peritoneum
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