Peripheral nerves contain sensory neurons and motor neurons that connect with the spinal cord. In cross-section, the spinal cord is divided into the butterfly-shaped grey matter and surrounding white matter.
Gray Matter - butterfly-shaped region that contains nerve cell bodies and supporting glial cells.
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.
Nissl Substance - basophilic material in nerve cell bodies and dendrites. The result of a large amount of RNA in free polyribosomes and rough endoplasmic reticulum (RER).
Axon - a single, large process that emerges from the nerve cell bodies at the axon hillock. Axons do not contain Nissl substance.
Dendrites - multiple processes extending from the nerve cell bodies that contain Nissl substance.
White Matter - 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.