The tissue shown in the image is which of the following?

• A. Spinal cord
• B. Brain
• C. Peripheral nerve
• D. Dorsal root ganglion

Answer: (A)

Recognizing spinal cord tissue comes down to the distinctive gray matter surrounded by white matter seen in cross-section. The gray matter forms a butterfly or H-shaped region with dorsal (posterior) horns and ventral (anterior) horns, where motor neurons reside in the ventral horn. A central canal may be visible in the center. The white matter encircles this gray core and contains myelinated tracts that run up and down the cord.

This pattern sets it apart from brain tissue, which would show cortex-like layering or cerebellar folia rather than a clear dorsal/ventral horn arrangement; from peripheral nerve, which would display fascicles organized by endoneurium, perineurium, and epineurium; and from a dorsal root ganglion, which would show clusters of large sensory neuron cell bodies with satellite cells, not the spinal gray matter with motor neurons.