 |
Proliferation of the connective tissue precursors in the endocardium cause deposition of the future fibrous skeleton, which partitions the early heart. Proliferation of the myocardium lays down the muscular layer of the contractile chambers of the developed heart. The chambers of the early heart are as follows:
| Sinus venosus (SV) | This is the collecting compartment of the heart. Oxygenated blood from the placenta and deoxygenated blood from embryonic tissues are mixed in the sinus. |
| Primitive atrium (PA) | This is the compartment destined for further partition to the definitive atria. |
| Primitive ventricle (PV) | This is the compartment destined for further partition to the definitive ventricles. |
| Bulbus cordis (BC) | This will contribute to the pulmonary trunk and aorta, along with the truncus arteriosus. |
| Truncus arteriosus (TA) | This will contribute to the aortic arches. |
| Fibrous skeleton (FS) | This is the area of connective tissue proliferation, site of future valves. |
A longitudinal section through the heart tube shows the arrangement of the early chambers.
|
|
Neural crest cell migrate into the truncus arteriosus and bulbus cordis, where they contribute to the aortico-pulmonary septum.
