Which feature would indicate viewing a longitudinal section of smooth muscle?

Which feature would indicate viewing a longitudinal section of smooth muscle?

• A. Circular profiles
• B. Striations
• C. Intercalated discs
• D. Parallel bundles of spindle-shaped cells

Answer: (D)

The main idea is how tissue orientation shows up in a histology slide. Smooth muscle cells are fusiform (spindle-shaped) and line up in parallel bundles. In a longitudinal section, you would see those elongated, spindle-shaped cells running in the same direction, which is exactly what “parallel bundles of spindle-shaped cells” describes. This contrasts with circular profiles, which come from cutting across the fibers (a cross-section); striations appear in skeletal and cardiac muscle; and intercalated discs are a feature of cardiac muscle. So the best indicator of a longitudinal view of smooth muscle is parallel bundles of spindle-shaped cells.

The main idea is how tissue orientation shows up in a histology slide. Smooth muscle cells are fusiform (spindle-shaped) and line up in parallel bundles. In a longitudinal section, you would see those elongated, spindle-shaped cells running in the same direction, which is exactly what “parallel bundles of spindle-shaped cells” describes. This contrasts with circular profiles, which come from cutting across the fibers (a cross-section); striations appear in skeletal and cardiac muscle; and intercalated discs are a feature of cardiac muscle. So the best indicator of a longitudinal view of smooth muscle is parallel bundles of spindle-shaped cells.