In a cross-section of smooth muscle, which pattern is seen?

In a cross-section of smooth muscle, which pattern is seen?

• A. Longitudinal fibers
• B. Nerve bundles
• C. Circular profiles
• D. Striations

Answer: (C)

Smooth muscle is organized into sheets that wrap around lumens, with spindle-shaped, non-striated cells. When you cut crosswise through a circular layer, the cells form rings around the lumen, so you see circular profiles. If you viewed a longitudinal section, you’d expect to see elongated, parallel fibers instead. Striations aren’t present in smooth muscle, which distinguishes it from skeletal or cardiac muscle. Nerve bundles may be nearby, but they don’t define the muscle’s pattern in cross-section. So the cross-section pattern you’d observe is circular profiles.

Smooth muscle is organized into sheets that wrap around lumens, with spindle-shaped, non-striated cells. When you cut crosswise through a circular layer, the cells form rings around the lumen, so you see circular profiles. If you viewed a longitudinal section, you’d expect to see elongated, parallel fibers instead. Striations aren’t present in smooth muscle, which distinguishes it from skeletal or cardiac muscle. Nerve bundles may be nearby, but they don’t define the muscle’s pattern in cross-section. So the cross-section pattern you’d observe is circular profiles.