Extra-toes (Xt) homozygous mutant mice demonstrate a role for the Gli-3 gene in the development of the forebrain.
The development of the forebrain in homozygous extra-toes mutants (Xt/Xt) was examined histologically from day 11.5 to day 16.5 of gestation. It is shown that until day 16.5 of gestation, the forebrains of Xt/Xt mutant embryos develop neither an olfactory bulb nor a choroid plexus in the lateral ventricles, and do not exhibit lamination in the cerebral cortex. Glial fibrillary acidic protein (GFAP)-expressing glial cells are detected in the prospective cerebral cortex of Xt/Xt animals, indicating that differentiation to glial cells is not disturbed. Upon comparison with a Splotch mutant, it is demonstrated that delayed closure of the anterior neuropore cannot account for the extra-toes specific defect in the developing cerebral cortex. It is, therefore, suggested that the forebrain phenotype in Xt/Xt mutant embryos is caused by the direct action of the mutation on the forebrain. As the zinc finger gene Gli-3 is deleted in extra-toes mutants, these observations suggest that the proper expression of the Gli-3 gene in the forebrain is a prerequisite for the normal development of the telencephalon and later of the cerebral cortex.
Abteilung für Neuroanatomie, Universitäts-Krankenhaus Eppendorf, Hamburg, Deutschland.
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D000818:Animals; D002540:Cerebral Cortex / Q000196:embryology* / Q000378:metabolism; D002831:Choroid Plexus / Q000196:embryology* / Q000378:metabolism; D005314:Embryonic and Fetal Development; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis / Q000276:immunology; D006720:Homozygote; D007150:Immunohistochemistry; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains / Q000196:embryology / Q000235:genetics*; D009830:Olfactory Bulb / Q000196:embryology* / Q000378:metabolism; D016548:Prosencephalon / Q000196:embryology*; D016335:Zinc Fingers / Q000235:genetics
D005904:Glial Fibrillary Acidic Protein