RESUMEN
Periostin, a member of the fasciclin gene family, acts as a cell adhesion molecule through binding to cell surface integrins. Periostin expression has previously been shown to increase substantially following transforming growth factor beta (TGF-beta) and bone morphogenetic protein stimulation. As these molecules are indispensable for cardiac development, we sought to clone the chicken ortholog of periostin and evaluate its spatiotemporal expression pattern during heart morphogenesis. We show by Northern analysis, whole mount and section in situ hybridization experiments that periostin is predominantly expressed in the developing endothelium of the ventricular trabeculae as well as in the endothelium and mesenchyme of the outflow tract and atrioventricular endocardial cushions. Cardiac expression continues into fetal development where periostin is seen predominantly in the valve leaflets and supporting chordae tendinae.