From the Guidelines
The myocardium originates from the mesoderm. The mesoderm is one of the three primary germ layers that form during early embryonic development. Specifically, the myocardium develops from a specialized region of the mesoderm called the cardiogenic mesoderm or heart field, as described in the study by the American Heart Association 1. During embryogenesis, cells from the cardiogenic mesoderm migrate and differentiate to form the muscular layer of the heart, known as the myocardium. This process begins around the third week of human embryonic development, with the primary heart field formed by early cardiac progenitor cells in the anterior mesoderm, and the secondary heart field derived from the pharyngeal mesoderm located medial and anterior to the primary heart field 1. Some key points about the development of the myocardium from the mesoderm include:
- The primary heart field contributes to the left ventricle and right and left atria
- The secondary heart field contributes to the right ventricle, outflow tract, and right and left atria
- Cardiac neural crest cells migrating from the dorsal neural tube into the arterial pole participate in separation of the outflow tract 1. The mesoderm origin of the myocardium explains why cardiac muscle cells share some characteristics with skeletal muscle (also derived from mesoderm) while having unique features suited for continuous contraction throughout life. Understanding this embryonic origin is crucial for research into cardiac development, regenerative medicine, and congenital heart defects.
From the Research
Embryological Origin of Myocardium
The embryological origin of the myocardium is a complex process that involves the differentiation of cells from specific germ layers.
- The myocardium develops from the mesoderm layer, specifically from the splanchnic mesoderm 2, 3, 4, 5.
- The splanchnic mesoderm gives rise to the myocardial and endothelial cells that form the primary heart tube 2, 5.
- The primary heart tube is then elongated and added to by the accretion of new myocardium from a secondary heart field of splanchnic mesoderm beneath the floor of the foregut 3.
- The myocardium of the outflow tract and the embryonic right ventricle are derived from the anterior heart field, which is a population of myocardial precursors located in the pharyngeal mesoderm 2, 4.
Germ Layer Involved
The germ layer involved in the development of the myocardium is the mesoderm.
- There is no evidence to suggest that the endoderm or ectoderm layers are directly involved in the development of the myocardium 2, 3, 4, 5, 6.
- The endoderm layer is involved in the development of other tissues, such as the lining of the gut and the respiratory system, but not the myocardium 5, 6.
- The ectoderm layer is involved in the development of tissues such as the skin, nervous system, and sensory organs, but not the myocardium 5, 6.