Smooth muscle Smooth muscle is found lining blood vessels, the intestine, and the urogenital tract . The relatively small spindle-shaped cells lack the striations characteristic of skeletal muscle fibers. Each cell has a single centrally located nucleus . Examine the slide of mammalian muscle and identify the section of smooth muscle under scanning power. Cardiac muscle Cardiac muscle is found only in the heart and in the aortic arch.
Striations are present, but the cells have a single, centrally located nucleus.
A specialized junction zone, called the intercalated disc , is present where cardiac muscle fibers are joined end to end. At intercalated discs, fibers often divide into 2 or more branches, which fuse to adjacent cells. Examine the slide under scanning power and identify the section of cardiac muscle. Examine the muscle under low and high power and note the individual fibers in longitudinal section and the location of the nucleus within each fiber. Observe the striations exhibited by the fibers - it may be necessary to reduce the light intensity to see the striations.