The truncus begins to divide about 29 days after conception. The division starts with the growth of two ridges derived from the limbs of the cardiac crescent. The ridges continue to grow in a spiral path toward the ventricles, eventually joining with tissue from the interventricular septum and closing the interventricular foramen. This tissue completes the separation of venous from arterial blood flow.
The truncus begins to divide about 29 days after conception. The division starts with the growth of two ridges derived from the limbs of the cardiac crescent. The ridges continue to grow in a spiral path toward the ventricles, eventually joining with tissue from the interventricular septum and closing the interventricular foramen. This tissue completes the separation of venous from arterial blood flow.