Dentate gyrus formation requires Emx2

Emx 1 and 2 are the murine homologues of the Drosophilaempty spiracles gene and based on their expression patternmay be involved in the regional specification of themammalian forebrain. During early embryogenesis, Emx2is expressed in the presumptive cerebral cortex andolfactory bulbs and later, in the hippocampus proper anddentate gyrus. The latter are involved in memory processes.To understand the role of Emx2 in vivo, we have mutatedthe gene in mice. Homozygous embryos die postnatallybecause of severe urogenital alterations. These micepresent cerebral hemispheres with a reduced size andexhibit specific morphological alterations in allocorticalstructures of the medial wall of the brain. The dentategyrus is missing and the hippocampus proper is reduced.The medial limbic cortex is also severely shortened. Thedevelopment of the dentate gyrus is affected at the onset ofits formation with defects in the neuroepithelium fromwhich it originates. These findings demonstrate that Emx2is required for the development of several forebrain structures.