Which section type is most appropriate to visualize intercalated discs in cardiac muscle?

Which section type is most appropriate to visualize intercalated discs in cardiac muscle?

• A. Longitudinal Section of Skeletal Muscle
• B. Cross Section of Skeletal Muscle
• C. Longitudinal Section of Cardiac Muscle
• D. Cross Section of Cardiac Muscle

Answer: (C)

Intercalated discs are end-to-end junctions between cardiac muscle cells that run along the length of the muscle fibers. To visualize these junctions clearly, you want to view the tissue in a longitudinal orientation, so the ends of many adjacent cells line up in a row and the discs appear as distinct dark lines connecting elongated cells. A longitudinal section of cardiac muscle thus reveals the intercalated discs most clearly. Cross-sections of cardiac muscle would show many roundish or polygonal cell profiles, and the junctions between cells wouldn’t line up along the plane of the cut, making intercalated discs harder to see. Skeletal muscle lacks intercalated discs altogether, so sections of skeletal muscle wouldn’t show these features, regardless of orientation.

Intercalated discs are end-to-end junctions between cardiac muscle cells that run along the length of the muscle fibers. To visualize these junctions clearly, you want to view the tissue in a longitudinal orientation, so the ends of many adjacent cells line up in a row and the discs appear as distinct dark lines connecting elongated cells. A longitudinal section of cardiac muscle thus reveals the intercalated discs most clearly.

Cross-sections of cardiac muscle would show many roundish or polygonal cell profiles, and the junctions between cells wouldn’t line up along the plane of the cut, making intercalated discs harder to see. Skeletal muscle lacks intercalated discs altogether, so sections of skeletal muscle wouldn’t show these features, regardless of orientation.