Phenotypes associated with this allele

• Allele Symbol: Amn^amn
• Allele Name: amnionless
• Allele ID: MGI:2135304
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Amn^amn/Amn^amn	involves: 129S1/SvImJ * C57BL/6J	MGI:3700771
hm2	Amn^amn/Amn^amn	involves: C57BL/6J	MGI:3700768

Genotype
MGI:3700771

hm1

• Allelic Composition: Amn^amn/Amn^amn
• Genetic Background: involves: 129S1/SvImJ * C57BL/6J

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

mortality/aging

embryonic lethality during organogenesis, incomplete penetrance ( J:51542 , J:68615 )

• most die between E9.5 and E10.5, however some continue development to E10.5, with resorption at E11.5 (J:51542)

embryo

embryo phenotype ( J:51542 )

N • Background Sensitivity: amnion is well developed on the mixed 129S1/SvImJ and C57BL/6 background while it is absent on a C57BL/6 background

abnormal ectoderm development ( J:51542 )

• the embryonic ectoderm of E8.5 mutants remains the size of that of a prestreak embryo and appears undifferentiated

• development of the embryonic ectoderm appears delayed by at least 1.5 days

caudal body truncation ( J:51542 )

• homozygotes that survive to E10.5 have a shortened trunk, however they do contain a notochord and a neural tube that has begun to close

embryonic growth arrest ( J:68615 )

absent mesoderm ( J:51542 )

• E8.5 embryos do not express the embryonic mesoderm markers Twist1 and Meox1 (Mox1), indicating that paraxial and lateral mesoderm are either not generated or that their generation is delayed

• homozygotes that survive to E10.5 have barely any mesoderm adjacent to the notochord and neural tube

absent primitive node ( J:51542 )

• a definitive node is absent at E8.5

abnormal primitive streak formation ( J:51542 )

• the middle region of the primitive streak is not appropriately assembled and appears absent

• however, the proximal and distal regions of the streak are properly organized and specified

absent somites ( J:51542 )

• absent somites

Genotype
MGI:3700768

hm2

• Allelic Composition: Amn^amn/Amn^amn
• Genetic Background: involves: C57BL/6J

mortality/aging

embryonic lethality during organogenesis, complete penetrance ( J:34163 )

• die between E9.5 and E10.5

embryo

increased embryonic tissue cell apoptosis ( J:50810 )

• embryos exhibit an increase in overall level of cell death, with high levels in the distal anterior region

abnormal ectoderm development ( J:34163 , J:51542 )

• embryonic ectoderm is small, underdeveloped, remains undifferentiated and generates no amnion (J:34163)

• development of the embryonic ectoderm appears delayed by at least 1.5 days (J:51542)

abnormal mesoderm development ( J:34163 )

• the mesoderm does not become organized into the node, notochord, and somites by E8.5

embryonic growth arrest ( J:34163 )

• homozygotes become developmentally arrested between the mid and late streak stages of gastrulation

abnormal embryonic tissue morphology ( J:50810 )

• at E7-7.5, embryos have a small embryonic region

absent mesoderm ( J:51542 )

• E8.5 embryos do not express the embryonic mesoderm markers Twist1 and Meox1 (Mox1), indicating that paraxial and lateral mesoderm are either not generated or that their generation is delayed

absent notochord ( J:34163 )

• no evidence of notochord production at E8.5

abnormal primitive streak morphology ( J:50810 )

• at E7-7.5 embryos have a short primitive streak

absent primitive node ( J:34163 , J:51542 )

• although the streak appears to extend to the distal tip of the egg cylinder, no recognizable node is detectable at the late streak stage (E7.5-7.75) or at E8.5 (J:34163)

• a definitive node is absent at E8.5 (J:51542)

abnormal primitive streak formation ( J:51542 )

• the middle region of the primitive streak is not appropriately assembled and appears absent

• however, the proximal and distal regions of the streak are properly organized and specified

absent somites ( J:34163 )

• no evidence of somite production

absent amnion ( J:34163 , J:51542 )

• although some mutants appear to form amniotic folds, no amnion is formed (J:34163)

• differentiation of other extraembryonic structures like the chorion, yolk sac blood islands and allantois occurs normally (J:34163)

• Background Sensitivity: amnion is absent on the C57BL/6 background, although the amniotic cavity forms by the epithelial embryonic ectoderm closing off on itself (J:51542)

nervous system

abnormal nervous system development ( J:34163 )

• show no evidence of neural induction

cellular

increased embryonic tissue cell apoptosis ( J:50810 )

• embryos exhibit an increase in overall level of cell death, with high levels in the distal anterior region