Expression of the helix-loop-helix factor, Hes3, during embryo development suggests a role in early midbrain-hindbrain patterning

The Hes gene family members are mammalian homologues of the Drosophila hairy and Enhancer of split genes. hairy and Enhancer of split function in both segmentation and in the Notch neurogenic pathway during Drosophila embryo development. Previous expression data suggested a conserved role for the Hes genes in the Notch signalling pathway, but not in segmentation. Here, Hes3 expression during mouse embryogenesis is described. During early development of the central nervous system, Hes3 is expressed specifically in the region of the midbrain/hindbrain boundary, and in rhombomeres 2, 4, 6 and 7. This pattern suggests that Hes3 may have a conserved role as a segmentation gene. Later in development, Hes3 is co-expressed with other neurogenic gene homologues in the developing central nervous system and epithelial cells undergoing mesenchyme induction. (C) 1997 Elsevier Science Ireland Ltd.