Analysis Tools
mortality/aging
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• less than 1% of mice survive to maturity
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• almost all mice die within one day of birth
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embryo
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• at the 6 somite stage, the ectoderm in the primitive streak is often 1 or 2 cells thicker apically to basally and is more acutely folded
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• at the 6 to 9 somite stage expression analysis indicates the posterior endoderm does not extend as far posteriorly and is delayed in folding ventrally to form the hindgut diverticulum
• at the 6 somite stage, the endoderm in the primitive streak is open ventrally failing to form a tubular hindgut
• by E10 absence of the tail gut is seen
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sirenomelia
(
J:152701
)
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• rare
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• variable degrees of segmental truncation typically confined to the tail but sometimes involving the sacral or lumbar regions
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• at E8.25 embryos are misshapen posterior to the somites in the region of the primitive streak
• at E8.25 the posterior region appears slightly spade shaped rather than rounded as in controls when viewed dorsally
• at the 6 to 7 somite stage the posterior length to width ratio is significantly decreased compared to controls
• however, the whole embryo length to width ratio is not significantly different from controls
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• at the 6 to 9 somite stage expression analysis indicates the posterior endoderm does not extend as far posteriorly and is delayed in folding ventrally to form the hindgut diverticulum
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• at E9.5, structures that normally separate left from right presomitic mesoderm terminate more anteriorly giving the tissue an abnormal Y shape rather than the normal U shape
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• the volume of presomitic mesoderm is normal but it is redistributed around the shortened axial and ventral structures
• at E9.5, structures that normally separate left from right presomitic mesoderm terminate more anteriorly giving the tissue an abnormal Y shape rather than the normal U shape
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spina bifida
(
J:152701
)
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• seen in most mice with severe truncations
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• by E10 the notochord is dramatically shorter compared to controls
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• at the 6 somite stage all 3 germ layers are present but morphologically abnormal
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• abnormalities are seen in somites formed at E9.5 or later
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• expression analysis detects disruptions in somitogenesis after E10 that are always accompanied by anatomical abnormalities
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• by E10 tail buds invariably show anatomical disorganization and evidence of histolysis
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digestive/alimentary system
absent anus
(
J:152701
)
|
• by E10 absence of the tail gut is seen
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• most neonates have blind-ended colons
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• adults display megacolon probably resulting from impaired digestive tract evacuation
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reproductive system
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• seen in rare survivors
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renal/urinary system
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• invariably seen when kidneys are present
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• in some mice
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• midline fusion is seen in some mice
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• ureters are present but most are connected at the midline or fused with the reproductive ducts
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• lack a urinary outlet
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• most neonates have no bladder
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limbs/digits/tail
sirenomelia
(
J:152701
)
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• rare
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• by E10 tail buds invariably show anatomical disorganization and evidence of histolysis
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• 73% display segmental truncation confined to the tail
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short tail
(
J:152701
)
skeleton
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• in 17% of mice segmental truncations extend into the sacral and lumbar regions
• typically the vertebrae immediately anterior to the truncation are smaller and malformed
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• 73% display segmental truncation confined to the tail
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nervous system
spina bifida
(
J:152701
)
|
• seen in most mice with severe truncations
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cardiovascular system
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• by E10 pockets of pooled blood and serous fluid are seen
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