MH 056 Muscle Types

Cardiac Muscle
(Phosphotungstic Acid/Hematoxylin)

Phosphotungstic acid/hematoxylin (PTAH) is used to demonstrate muscle striations, intercalated discs, nervous tissue and fibrin.

Tissue sections of skeletal, cardiac and smooth muscle are shown.

The longitudinal section of cardiac muscle stained with PTAH shows the morphology of individual cardiac muscle cells, and in particular, the intercalated discs.

• Branched Cells - cells are joined end-to-end and are often branched. They are 50 to 250 µm in length
• Nuclei - cells have a single or occasionally two centrally located nuclei.
• Intercalated Discs - specialized junctions that connect the individual cells (arrows). They appear as dark purple bands across muscle fibers.
• Lipofuscin Pigment - residue of lysosomal digestion that accumulates as yellow-brown granules next to the nucleus of some cells.

Cardiac muscle does not contain cells equivalent to the satellite cells of skeletal muscle.

The ultrastructure of intercalated discs is seen in EM 122 Cardiac Muscle by transmission electron microscopy.