Uberon Homology note : The fish heart displays clear polarity of contraction in a posterior-to-anterior direction.
The contraction waves originate in the sinus venosus and terminate in the conus arteriosus.
The nodal phenotype persists in the inflow region of the heart, varying from the venosinus
to the sinoatrial junctional areas in different species . Similar to the mammalian
situation, pacemaker tissue with a lower intrinsic rhythmicity is also found at the
atrioventricular junction.[uncertain][VHOG];