Figure 3.

Early heart morphogenesis in human and mouse. In Carnegie stage 9, or approximately day 20 of gestation, the heart resembles a “trough” because the heart has not yet closed dorsally. By Carnegie stage 10, or approximately day 22 of gestation, the linear heart tube has formed around a single lumen and the heart tube has liberated itself from the coelomic wall, except at the inflow and outflow. By Carnegie stage 11, or approximately day 24 of gestation, the heart tube has looped and early stages of ballooning of the left ventricle (LV) can be seen. In mouse, within few hours around embryonic day 8, the heart transitions from a trough to a looped tube with early chamber formation. (myo) Myocardium. (The figure is based on 3D models in Sizarov et al. 2011 and de Boer et al. 2012.)