Hearbeat Establishes Blood Supply In Embryo

Seeing that heartbeat in an embryo is such a thrill. It really sinks in that you have a real life inside of you. This article talks about the importance of the first heartbeats:

www.newscientist.com

from the article:

As the heart starts pumping a primitive blood-like fluid around the body of an embryo, the change in pressure from the flowing liquid is the cue for cells lining the aorta to change first into blood stem cells, then into all blood-cell types in the body. As they multiply and mature, these rapidly replace the initial embryonic "blood", which is composed of embryonic red blood cells in a nutrient-rich serum.