Neurohistology

An axon (from ; also called a nerve fiber or fibre) is a long slender projection of a nerve cell or neuron found in most animals that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain sensory neurons (pseudounipolar neurons), such as those for touch and warmth, the axons are called afferent nerve fibers and the electrical impulse travels along these from the periphery to the cell body and from the cell body to the spinal cord along another bra

main component of the nervous system

[[File:Anatomy of neuron.png|thumb|500px|The neuron contains dendrites that receive information, a cell body called the soma, and an axon that sends information to other cells through the synapses. Schwann cells make the signals (action potentials) move faster down the axon. Please see learnbio.org for interactive version.]] A dendrite (from Greek δένδρον déndron, "tree") or dendron is a branched cytoplasmic process extending from a nerve cell; it propagates the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites projec

thumb|right|A dorsal root ganglion (DRG) from a chicken embryo (around stage of day 7) after incubation overnight in NGF growth medium stained with anti-neurofilament antibody. Note the axons growing out of the ganglion.

Myelin ( ) is a lipid-rich material that in most vertebrates surrounds the axons of neurons to insulate them and increase the rate at which electrical impulses (called action potentials) pass along the axon. The myelinated axon can be likened to an electrical wire (the axon) with insulating material (myelin) around it. However, unlike the plastic covering on an electrical wire, myelin does not form a single long sheath over the entire length of the axon. Myelin ensheaths part of an axon known as an internodal segment, in multiple myelin layers of a tightly regulated internodal length.

axon part that is a gap in the myelin where voltage-gated sodium channels cluster and saltatory conduction takes place

the portion of the cell soma (neuronal cell body) that excludes the nucleus

Portion of the neuronal cell soma from which the axon originates.

small, membranous protrusion from a dendrite that forms a postsynaptic compartment

nerve fiber part

The epineurium is the outermost layer of dense irregular connective tissue surrounding a peripheral nerve. It usually surrounds multiple nerve fascicles as well as blood vessels which supply the nerve. Smaller branches of these blood vessels penetrate into the perineurium. In addition to blood vessels which supply the nerve, lymphocytes and fibroblasts are also present and contribute to the production of collagen fibers that form the backbone of the epineurium. In addition to providing structural support, lymphocytes and fibroblasts also play a vital role in maintenance and repair of the surro

silver staining technique for visualizing nervous tissue under light microscopy

The endoneurium (also called endoneurial channel, endoneurial sheath, endoneurial tube, or Henle's sheath) is a layer of delicate connective tissue around the myelin sheath of each myelinated nerve fiber in the peripheral nervous system. Its component cells are called endoneurial cells. The endoneuria with their enclosed nerve fibers are bundled into groups called nerve fascicles, each fascicle within its own protective sheath called a perineurium. If sufficiently large, nerves containing multiple fascicles, each with its blood supply and fatty tissue, may be bundled within yet another sheath,

The perineurium is a protective sheath that surrounds a nerve fascicle. This bundles together axons targeting the same anatomical location. The perineurium is composed from fibroblasts.

Axoplasm is the cytoplasm within the axon of a neuron (nerve cell). For some neuronal types this can be more than 99% of the total cytoplasm.

concept that the nervous system is made up of discrete individual cells

In neuroscience, the axolemma (, and 'axo-' from axon) is the cell membrane of an axon, the branch of a neuron through which signals (action potentials) are transmitted. The axolemma is a three-layered, lipid bilayer membrane. Under standard electron microscope preparations, the structure is approximately 8 nanometers thick.

Neurilemma (also known as neurolema, sheath of Schwann, or '''Schwann's sheath''') is the outermost nucleated cytoplasmic layer of Schwann cells (also called neurilemmocytes) that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system.

anatomical region

bundle of funiculi (small bundles of axons)

Regions within compact myelin in which the cytoplasmic faces of the enveloping myelin sheath are not tightly juxtaposed, and include cytoplasm from the cell responsible for making the myelin. Schmidt-Lanterman incisures occur in the compact myelin in

one of the three classes of nerve fiber

electron-dense network of proteins within and adjacent to the postsynaptic membrane of an asymetric, neuron-neuron synapse