MH 058a Heart

Purkinje Fibers
(Periodic Acid - Schiff Stain)

Purkinje fibers are specialized cardiac muscle cells that conduct electrical impulses that allow coordinated contraction of cardiac muscle.

Purkinje fibers have fewer myofibrils, but a higher content of glycogen than normal cardiac muscle cells. This allows their identification with periodic acid-Schiff (PAS) stain which chemically converts sugars in glycogen into a magenta-colored product (see MH 128 Liver - Glycogen).

The endocardium is at the right of this specimen.

Beneath the endocardium are the strongly, PAS-stained (dark magenta) cardiac muscle cells. This high concentration of glycogen is characteristic of Purkinje cells.

Normal cardiac muscle cells which store little glycogen occur to the left of the Purkinje cells.

(The cardiac skeleton is also stained in this specimen because it contains fibrocartilage. The chondrocytes are PAS positive.)