Ingression, migration and early differentiation of cardiac progenitors

During vertebrate embryogenesis the heart is the first functioning organ and cardiac progenitor cells (CPCs), which form the future heart, are among the first cell types to be established during gastrulation. A large number of studies indicate that cardiac development is tightly regulated by a series of molecular signaling pathways and morphological events. The cellular and molecular events that control early cardiac development are conserved among vertebrates. The favorable experimental characteristic of the chicken embryo and the ease in which cell labeling and imaging can be performed has allowed direct observation of the process of gastrulation and cell migration trajectories. This has enabled the study of the signaling proteins and molecular pathways required to specify early embryonic cells to the myocardial lineage. In this review we discuss the major morphogenetic and regulatory events that control gastrulation and migration of CPCs in the chicken embryo. We also describe the signaling mechanisms critical for early CPC specification in pre-gastrula, gastrula and early neurula stage embryos.