Abstract
An increasing number of axon guidance cues have been shown recently to play important roles in the development of non-neural tissues. Semaphorins comprise one of the largest conserved families of axon guidance factors. We analyzed the expression patterns of Sema3D, Sema3F, and Sema5A genes in the chick embryonic heart by in situ hybridization. All three genes are expressed in the cardiac cushion regions, both in the mesenchymal cells, and epithelial cells in the endocardial layer, during the period of cardiac remodeling. In addition to the overlapping expression patterns in the cardiac cushion regions, these genes also exhibit distinct expression patterns in the developing heart: Sema3D is additionally expressed in the tips of the ventricular trabeculae; Sema3F is expressed in a subset of cells scattered throughout the ventricles; and Sema5A is expressed in the newly formed atrioventricular valves. The overlapping and distinct expression patterns of these genes suggest that they may play important roles in heart development.