Changes

The heart tube grows rapidly forcing it to bend upon itself resulting in the bulboventricular loop. Septa begin to grow in the atria, ventricle and bulbus cordis forming right and left atria, right and left ventricles and two great vessels - the pulmonary artery and the aorta.

The heart tube grows rapidly forcing it to bend upon itself resulting in the bulboventricular loop. Septa begin to grow in the atria, ventricle and bulbus cordis forming right and left atria, right and left ventricles and two great vessels - the pulmonary artery and the aorta.

The processes involved in forming a simple heart, such as that in a fish, or a multi-chambered heart, as seen in oxygen-breathing vertebrates, follows similar pathways.

The processes involved in forming a simple heart, such as that in a fish, or a multi-chambered heart, as seen in oxygen-breathing vertebrates, follow similar pathways.