Neurons: The Cell Body and the Dendrites

The cell body, or perikaryon, is the metabolic center of a neuron containing the nucleus surrounded by cytoplasm with organelles including mitochondria. It houses Nissl bodies—clusters of ribosomes and rough endoplasmic reticulum responsible for protein synthesis—which give gray matter its characteristic color. The cell body also contains the cytoskeleton, including neurofibrils and microtubules that support the neuron and transport materials.

Dendrites are slender, highly branched cellular processes extending from the cell body covered with dendritic spines that enhance surface area for signal reception. Their plasma membrane is rich in receptors that bind neurotransmitters—chemical messengers released by neighboring neurons. Dendrites relay this information to the cell body through short-distance electrical impulses called graded potentials.

Neurofibrils are bundles of intermediate filaments that provide structural support to neurons. Microtubules, part of the cytoskeleton, are essential for transporting materials between the cell body and the axon. Together, these cytoskeletal components maintain neuronal integrity and enable the movement of vital substances throughout the cell.

Nissl bodies are clusters of ribosomes and rough endoplasmic reticulum found in the neuronal cell body that are responsible for protein synthesis. These structures give gray matter its distinctive gray color. As neurons age, lipofuscin—a brown pigment produced by lysosomes—accumulates alongside Nissl bodies, reflecting cellular aging.

Groups of neuron cell bodies in the central nervous system are called nuclei, while in the peripheral nervous system they are called ganglia. This organizational distinction reflects the different structural and functional roles these regions play in the nervous system. Understanding this terminology is essential for studying nervous system anatomy.

Dendritic spines are tiny protrusions covering dendrites that form synapses with neighboring neurons. These structures increase the surface area available for receiving signals, enhancing the dendrite's capacity to bind neurotransmitters and receive information. This structural feature is critical for efficient synaptic communication between neurons.

The neuronal cell body contains a nucleus, mitochondria for energy production, and Nissl bodies for protein synthesis. The cytoplasm also includes other standard cellular organelles. These organelles work together to maintain the cell's metabolic functions and support the neuron's ability to generate and transmit electrical signals.