Cardiac Muscle Tissue with Purkinje Fibers

Note - Arrows are pointing to Purkinje fibers which are larger than cardiac muscle fibers.
They also appear lighter due to the absence of myofibers.
Purkinje fibers transmit the action potential through the heart muscle to the heart apex first,
which is faster and more direct than cell to cell conduction.
This allows for the heart to contract as a whole beginning the contraction at the heart apex.

Cardiac Muscle             AP II Tissues