UCSF 163 Spinal Cord

Spinal Cord
(Cresyl Violet)

Cross section of the spinal cord stained with cresyl violet. Cresyl violet is a basic dye that binds nucleic acids and preferentially stains RNA.

In cross-section, the spinal cord is divided into the butterfly-shaped grey matter and surrounding white matter. Nuclei of all cells and the Nissl (chromophil) substance in neurons is stained.

• Gray Matter - butterfly-shaped region that contains nerve cell bodies and supporting glial cells. Synapses only occur in gray matter.
  • Dorsal Horns (left, right) - upper parts of the wings that receive sensory input from peripheral neurons.
  • Ventral Horns (left, right) - lower parts of the wings that contain the cell bodies of motor neurons that give rise to the motor portion of peripheral nerves.
• White Matter - surrounds the gray matter and contains ascending and descending axons (bundled into tracts) and supporting glial cells.
• Central Canal - small, round structure in the center of the spinal cord that contains cerebral spinal fluid. Lined with a simple cuboidal-to-columnar epithelium of ependymal cells.

Some cells can be identified by their location, size, and morphology.

• Motor Neurons - large cell bodies in the ventral horn that can be more than 100 µm in diameter (innervate striated muscle).
  • Nucleus - large with a prominent nucleolus
  • Nissl (Chromophil) Substance - basophilic material in nerve cell bodies and dendrites (left). The result of a large amount of RNA in rough endoplasmic reticulum and free polyribosomes.
  • Axon (right) - a single, large process that emerges from the nerve cell bodies at the axon hillock (right). Note that the axon does not contain Nissl substance.
  • Dendrites (left) - multiple processes extending from the nerve cell bodies that contain Nissl substance
• Glial Cells - the small nuclei found around the motor neurons are mostly glial cells.