mortality/aging
• homozygotes develop to term but die within 24 hrs of birth
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nervous system
• at E9.5, homozygotes display a shorter than normal metencephalic rhombomere-1 (r1)
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• at E9.5, the caudal two-thirds of the midbrain fail to develop whereas the remaining (presumably rostral) one-third is present
• notably, most of the neural tube and all non-neural tissues appear normal
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• at E16.5, homozygotes show an abnormal cranial flexure due to neural tissue loss; however, the thalamus and pons appear normal
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• at E9.5, a normal midbrain-metencephalic junction fails to develop
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• by E14.5, most, if not all, of the mutant midbrain is absent
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• at E9.5, absence of primitive brain tissue moves the forebrain caudally, resulting in a novel juxtaposition of rostral midbrain with caudal metencephalon
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• at E9.5, homozygotes show absence of rostral metencephalic tissue
• at E14.5 and E16.5, dorsally-derived cerebellar tissue is absent whereas the ventrally-derived pons is present
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• by E14.5, homozygotes lack an identifiable cerebellum; in contrast, the posterior choroid plexus is present, and the cerebral hemisphere, diencephalon, myelencephalon, and spinal cord appear normal
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skeleton
• at E18.5, homozygotes lack part of the parietal bone, a non-crest derivative
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craniofacial
• at E18.5, homozygotes lack part of the parietal bone, a non-crest derivative
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hematopoietic system
• at E15-E16, homozygotes show a 20-30% reduction in thymocyte number relative to wild-type embryos
• however, T cell maturation during fetal development appears unaffected
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immune system
• at E15-E16, homozygotes show a 20-30% reduction in thymocyte number relative to wild-type embryos
• however, T cell maturation during fetal development appears unaffected
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embryo
• at E9.5, homozygotes display a shorter than normal metencephalic rhombomere-1 (r1)
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endocrine/exocrine glands
• at E15-E16, homozygotes show a 20-30% reduction in thymocyte number relative to wild-type embryos
• however, T cell maturation during fetal development appears unaffected
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