Nissl bodies in neurons of the spinal cord

Nissl bodies (also called Nissl granules, Nissl substance or tigroid substance) are discrete granular structures in

neurons A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...

that consist of rough

endoplasmic reticulum The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...

, a collection of parallel, membrane-bound cisternae studded with

ribosomes Ribosomes ( ) are macromolecular machines, found within all cells, that perform biological protein synthesis (mRNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA (mRNA) molecules to f ...

on the cystosolic surface of the membranes. Nissl bodies were named after

Franz Nissl Franz Alexander Nissl (9 September 1860, in Frankenthal – 11 August 1919, in Munich) was a German psychiatrist and medical researcher. He was a noted neuropathologist. Early life Nissl was born in Frankenthal to Theodor Nissl and Maria Haas ...

, a German

neuropathologist Neuropathology is the study of disease of nervous system tissue, usually in the form of either small surgical biopsies or whole-body autopsies. Neuropathologists usually work in a department of anatomic pathology, but work closely with the clinic ...

who invented the staining method bearing his name ( Nissl staining). The term "Nissl bodies" generally refers to discrete clumps of rough endoplasmic reticulum in nerve cells. Masses of rough endoplasmic reticulum also occur in some non-neuronal cells, where they are referred to as

ergastoplasm The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...

, basophilic bodies, or chromophilic substance. While these organelles differ in some ways from Nissl bodies in neurons, large amounts of rough endoplasmic reticulum are generally linked to the copious production of proteins.

Staining

"Nissl stains" refers to various basic dyes that selectively label negatively charged molecules such as DNA and

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

. Because ribosomes are rich in

ribosomal RNA Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal ...

, they are strongly

basophilic Basophilic is a technical term used by pathologists. It describes the appearance of cells, tissues and cellular structures as seen through the microscope after a histological section has been stained with a basic dye. The most common such dye is ...

("base-loving"). The dense accumulation of membrane-bound and free ribosomes in Nissl bodies results in their intense coloration by Nissl stains, allowing them to be seen with a light

microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...

Size and distribution

Nissl bodies occur in the

somata The soma (pl. ''somata'' or ''somas''), perikaryon (pl. ''perikarya''), neurocyton, or cell body is the bulbous, non-process portion of a neuron or other brain cell type, containing the cell nucleus. The word 'soma' comes from the Greek '' σῶ� ...

and

dendrites Dendrites (from Greek δένδρον ''déndron'', "tree"), also dendrons, are branched protoplasmic extensions of a nerve cell that propagate the electrochemical stimulation received from other neural cells to the cell body, or soma, of the n ...

of neurons, though not in the

axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action po ...

axon hillock The axon hillock is a specialized part of the cell body (or soma) of a neuron that connects to the axon. It can be identified using light microscopy from its appearance and location in a neuron and from its sparse distribution of Nissl substance. ...

. They vary in size, shape, and intracellular location; they are most conspicuous in the

motor neurons A motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly ...

of the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...

and

brainstem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is cont ...

, where they appear as large, blocky assemblies. In other neurons, they may be smaller, and in some (such as the granule neurons of the

cerebellar The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebel ...

cortex) very little rough endoplasmic reticulum is present. The pattern of coloration with Nissl stains once was used to classify neurons. For various reasons, this practice has largely ceased, but specific neuronal types do manifest characteristic types of Nissl bodies.

Functional role

The functions of Nissl bodies are thought to be the same as those of the rough endoplasmic reticulum in general, primarily the synthesis and segregation of proteins. Similar to the ergastoplasm of

glandular In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

cells, Nissl bodies are the main site of protein synthesis in the neuronal

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The ...

. The

ultrastructure Ultrastructure (or ultra-structure) is the architecture of cells and biomaterials that is visible at higher magnifications than found on a standard optical light microscope. This traditionally meant the resolution and magnification range of a co ...

of Nissl bodies suggests they are primarily concerned with the synthesis of proteins for intracellular use.

Pathology

Nissl bodies show changes under various physiological conditions and in

pathological Pathology is the study of the causal, causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when us ...

conditions such as

axonotmesis Axonotmesis is an injury to the peripheral nerve of one of the extremities of the body. The axons and their myelin sheath are damaged in this kind of injury, but the endoneurium, perineurium and epineurium remain intact. Motor and sensory functions ...

, during which they may dissolve and largely disappear (

chromatolysis Chromatolysis is the dissolution of the Nissl bodies in the cell body of a neuron. It is an induced response of the cell usually triggered by axotomy, ischemia, toxicity to the cell, cell exhaustion, virus infections, and hibernation in lower vert ...

). If the neuron is successful in repairing the damage, the Nissl bodies gradually reappear and return to their characteristic distribution within the cell.

References

External links

* * * - "Nervous Tissue and Neuromuscular Junction: spinal cord, cell bodies of anterior horn cells"
Histology at anhb.uwa.edu.auTissues containing Nissl bodies at harvard.edu
{{Nervous tissue Nervous tissue cells