Figure 1: The formation of the Heart Tube during embryogenesis. Photo courtesy Charles C. Lawrence.
The heart is one of the most important organs that is in the human body, and without it we would clearly not be here. The heart is one of the first structures that form during organogenesis and it comes from the embryonic mesoderm, initially forming a tube like structure consisting of an endothelial sheet of simple squamous cells which is the endocardium and the outer layer which is the myocardium consisting of concentric layers of cardiac myocytes (contractile function). The next layer is the epicardium which is the outer most layer and is made up of squamous cells layered on a basal lamina along with connective tissue. As development proceeds, the heart begins to loop around and partition itself into a more familiar shape. The next major phase is for the atria to separate from each other, leaving only one large ventricle which will then separate, forming the four chambered heart (Wolpert, 2007). The heart starts to beat 21 days after conception.
Interesting Facts:
- 1 out of 100 births in infants results in some sort of congenital heart malformation.
- The heart rate is greatest during infant years, beating 120 beats/min and once the age of 18 is reached the heart slows to 70 beats/min.
- Newt Zebrafish are capable of regenerating their myocardium even if a large portion is removed.
