Differential expression of the islet-1 homeodomain protein in the limb bud of the chick embryo

Abstract.

Islet-1 and Islet-2 are members of a family of homeodomain-containing transcription factors, and Islet-1 has been shown to be involved in differentiation of several cell types. The expression pattern of Islet-1 and Islet-2 was examined in the presumptive limb buds of early chick embryos by using specific monoclonal antibodies. Prior to and during limb bud emergence, mesenchymal cells in the presumptive leg bud, but not in the wing bud, expressed Islet-1. In addition, the apical ectodermal ridge in both wing and leg buds expressed Islet-1. In contrast, Islet-2 was not expressed in limb buds.