In situ analysis of the cardiac muscle gene program during embryogenesis.

During the last decade, gene expression in cardiac muscle of the developing embryo has been examined in situ with the use of nucleic acid probes and antibodies. With growth and maturation from a simple tube to a four-chambered organ, the myocardium undergoes a complex series of developmental changes in the temporal and spatial expression patterns of a number of structural and transcription factor genes. Studies of embryonic hearts suggest that different populations of cardiac myocytes might appear during development. These in vivo results are summarized and discussed in the context of the morphogenetic events that shape the myocardium.