What are groups of neuron cell bodies in the central nervous system (grey matter) called?

• A. Nuclei
• B. Ganglia
• C. Cortex
• D. Fibers

Answer: (A)

Groups of neuron cell bodies in the central nervous system are called nuclei. The CNS uses the term nucleus (plural nuclei) to name clusters of neuronal somata that typically share a function and are located within the brain or spinal cord. This distinguishes them from the peripheral nervous system, where similar clusters are termed ganglia.

The cerebral cortex, by contrast, is the outer layer of gray matter folded over the brain—rich in cell bodies but described as a region rather than a generic cluster. Fibers refer to bundles of axons, which form white matter and carry signals between regions, not collections of cell bodies.

So, the correct term for groups of neuron cell bodies in the CNS is nuclei.