Phenotypes Associated with This Genotype

Genotype
MGI:2654110

• Allelic Composition: Acvr1b^tm1Enl/Acvr1b^tm1Enl
• Genetic Background: either: (involves: 129S4/SvJae) or (involves: 129S4/SvJae * C57BL/6)

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

mortality/aging

embryonic lethality during organogenesis, complete penetrance ( J:46637 )

• at E8.5, about 25% of decidua contain abnormal conceptuses in which the embryos are either very small or completely resorbed

• no homozygous embryos are recovered at, or after, E9.5

cellular

abnormal cell differentiation ( J:46637 )

• homozygous null ES cells injected into wild-type blastocysts are capable of forming mesoderm in chimeric embryos; however, primitive streak formation is impaired

• wild-type ES cells injected into homozygous null blastocysts form relatively normal extraembryonic tissues and extraembryonic mesoderm; however, the embryo proper develops poorly, suggesting a severe gastrulation defect

embryo

embryonic growth arrest ( J:46637 )

• expression of Brachyury (T), an early mesoderm marker, is absent at E7.5 and E8.5, suggesting that developmental arrest occurs before gastrulation

abnormal embryonic epiblast morphology ( J:46637 )

• at E6.5, the epiblast of some embryos is hypoplastic and often located ectopically

absent egg cylinders ( J:46637 )

• molecular marker analysis of prestreak stage embryos confirmed that the visceral endoderm fails to form the squamous cell type in the distal region of the egg cylinder

absent mesoderm ( J:46637 )

• at E7.5, mutant embryos contain no mesoderm

failure of primitive streak formation ( J:46637 )

• at E7.5, 12 out of 38 homozygous null embryos appear smaller and lack a discernible primitive streak

abnormal extraembryonic ectoderm morphology ( J:46637 )

• at E6.5, the extraembryonic ectoderm cells fail to form an epithelial layer and often intrude into the distal region

disorganized extraembryonic tissue ( J:46637 )

• at E6.5, the epiblast and the extraembryonic ectoderm appear to be intertwined and disorganized

abnormal visceral endoderm morphology ( J:46637 )

• at E8.5, the visceral endoderm layer is folded, possibly as a result of extensive cell death and shrinkage of the ectoderm

• no morphological defects are noted in the trophoblast or parietal endoderm throughout early development

abnormal distal visceral endoderm morphology ( J:46637 )

• at E5.5, in ~22% of mutant embryos, the distal visceral endoderm cells are slightly more vacuolated and detached from the epiblast