Which substance consists mostly of cell bodies and dendrites in the nervous system?

• A. White matter
• B. Grey matter
• C. Nerve fibers
• D. Cerebellum

Answer: (B)

Grey matter is the tissue in the nervous system that is rich in neuron cell bodies and their dendrites. It contains the cell bodies themselves, the branching dendrites, and supporting glial cells, with relatively little myelin around the neuron's long axons, which gives this region its characteristic grey appearance. This is the area where most synapses occur and local processing of information happens. By contrast, white matter is dominated by myelinated axons that form long communication pathways between brain regions. The cerebellum is a structure that contains both grey and white matter, so it isn’t the substance itself. Nerve fibers refer to axons, which are more abundant in white matter. So the tissue described as mostly cell bodies and dendrites is grey matter.