mortality/aging
• homozygous embryos die between E3.5 (when the expected number of homozygous embryos are found) and E7.5 (when no homozygous embryos are found)
• embryos die in utero due to apoptosis of the blastocyst cells between E3.5 and E4.0
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cellular
• extensive apoptosis is seen in E3.5 homozygous embryos after only 2 - 3 hours in culture while only rare apoptotic cells are seen in wild-type embryos
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• more cells from E3.5 homozygous embryos (50 - 60%) are positive for a mitosis-specific marker compared to wild-type (~10%) suggesting null embryos arrest in mitosis before E3.5
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embryo
• extensive apoptosis is seen in E3.5 homozygous embryos after only 2 - 3 hours in culture while only rare apoptotic cells are seen in wild-type embryos
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• in culture, E2.5 - E3.5 homozygous embryos fail to hatch out of the zona pellucida
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• at E2.5 homozygous embryos appear identical to wild-type embryos
• at E3.5 homozygous embryos fail to form fully expanded blastocysts and appear retarded at the morula stage
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