mortality/aging
• embryos developing to term are either born dead or become cyanotic within minutes after birth due to respiratory failure
(J:85949)
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• more than 1/3 (42/70) of embryos die between E12.5 and E15.5
(J:85949)
• most die between E12.5 and E16.5 due to heart failure or perinatally due to inability to breathe
(J:85950)
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• more than 1/3 (42/70) of embryos die between E12.5 and E15.5
(J:85949)
• most die between E12.5 and E16.5 due to heart failure or perinatally due to inability to breathe
(J:85950)
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growth/size/body
• most mutants are 20% smaller in size than wild-type
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respiratory system
• most lungs are developmentally arrested around the early saccular stage since air saccules fail to form
• marker analysis indicates impaired proximal and distal epithelial cell differentiation
• however, airway branching is not impaired
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• neonatal lungs fail to inflate
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cardiovascular system
• a delay or reduction in the development of the coronary vessel network is apparent by E13.5
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• reduction in muscle mass of heart
• retardation of myocardium development
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• about 80% of embryos show a reduction in myocardial compact layer thickness of both ventricular chambers
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• reduction in thickness of the myocardium is first visible at E11 and is primarily in the ventricular but not atrial wall
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• more severe than in Crebbptm1Reck heterozygotes
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• epicardium formation is not complete at E11 but the epicardium is formed around most hearts by E12.5
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• mutants exhibit a delay in heart development
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• three embryos have an atrial septum closure defect (ASD)
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• atrial septum closure defect (ASD) is associated with an underdeveloped atrioventricular septum
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• ventricular septum closure defect (VSD) is seen in 7/8 mutants at E14.5 and in 5/6 mutants at E15.5, however by E16.5 most mutants have a closed ventricular septum, indicating a 2-3 day delay in closure
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• mutants with little myocardial thinning also have underdeveloped leaflets and a VSD, however this is restricted to the membranous part located at the tip of the septum
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• VSD is accompanied by underdeveloped or malformed valve leaflets
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• some hearts show a thin ventricular wall prior to the onset of vascularization
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hemorrhage
(
J:85949
)
• edema is often accompanied by peripheral hemorrhage, however by E16.5 and E18.5, mutants no longer exhibit edema and hemorrhage
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• about 1/3 of embryos at E13.5 exhibit blood leakage around ventricles
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digestive/alimentary system
• the thickness of the epithelial cell layer of the midgut is greatly expanded
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• mutants exhibit increased mesenchymal cell proliferation in the small intestine at E18.5
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• delay in villi formation by 2-4 days in the small intestine, showing no mesenchymal invagination at E14.5 and E16.5
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muscle
• mutants exhibit a reduction in the size of muscle by E14.5
• reduction in muscle size is not due to decreased proliferation, increased apoptosis or impaired migration of muscle precursors into the limb buds
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• reduction in muscle mass of heart
• retardation of myocardium development
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• about 80% of embryos show a reduction in myocardial compact layer thickness of both ventricular chambers
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• reduction in thickness of the myocardium is first visible at E11 and is primarily in the ventricular but not atrial wall
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• marker analysis indicates impaired muscle formation
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• interfibrillar space of muscle fibers at E18.5 is increased
• muscle fibers appear loose and disorganized at E18.5
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• muscle fiber size is reduced at E14.5 and E18.5 in trapezius, tongue, diaphragm, and intercostal muscles
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homeostasis/metabolism
• edema is seen in all mutants at E14.5 and E15.5, however most embryos aged E16.5 to E18.5 no longer exhibit edema
(J:85949)
• all mutants at E14.5 exhibit peripheral edema
(J:85950)
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