What structure is indicated by the arrow?

What structure is indicated by the arrow?

• A. Smooth muscle fiber
• B. A neuron cell body
• C. Skeletal muscle fiber
• D. Capsule of sympathetic ganglion

Answer: (D)

The main idea is recognizing the protective wrapping around a sympathetic ganglion. The arrow points to the outer fibrous boundary that encloses a cluster of neuron cell bodies, known as the capsule. This connective tissue capsule stands apart from the cells inside: the neuron cell bodies themselves would look like round or oval cells with large nuclei and Nissl substance, not as an outer boundary. Skeletal muscle fibers are long, multinucleated fibers, and smooth muscle fibers are spindle-shaped cells found in walls of organs, not forming a boundary around a ganglion. So the ring-like structure seen surrounding the group of neurons is the capsule of the sympathetic ganglion.

The main idea is recognizing the protective wrapping around a sympathetic ganglion. The arrow points to the outer fibrous boundary that encloses a cluster of neuron cell bodies, known as the capsule. This connective tissue capsule stands apart from the cells inside: the neuron cell bodies themselves would look like round or oval cells with large nuclei and Nissl substance, not as an outer boundary. Skeletal muscle fibers are long, multinucleated fibers, and smooth muscle fibers are spindle-shaped cells found in walls of organs, not forming a boundary around a ganglion. So the ring-like structure seen surrounding the group of neurons is the capsule of the sympathetic ganglion.