What is the Pumping Mechanism Behind Embryonic Hearts?

During this initial phase of the development the embryonic heart consist only of a contractile tube lacking valves. There has been recent debate as to how this valveless heart can generate uni-directional flow. Recently Forouhar et al. proposed a mechanism for the zebrafish embryo based on dynamic suction previously described as the Liebau effect [1]. Dynamic suction pumping is characterized by one stationary point of activation, inducing waves which then travel passively along the primitive heart tube. The passive waves create the blood flow. Peristalsis on the other hand is characterized by a series of adjacent contraction locations creating the appearance of a travelling wave along the wall. In this investigation we begin to determine how the embryonic vertebrate heart functions.