Nissl bodies: anatomy, characteristics and functions

Research and exploration of the human brain and the structures that are part of it have been constant since ancient times. The neuron As a basic unit of the nervous system, it has been specially investigated, using strategies such as the use of different stains to observe its structure.

The German neurologist Franz Nissl developed a stain based on dyes such as toluidine blue or cresyl violet, and before his application was able to observe how this substance clearly showed the existence of different structures in the neuronal cytoplasm. They had discovered what we know today as corpuscles or Nissl bodies.

Nissl bodies: what are they?

Nissl bodies or ergastoplasma are small structures in the form of corpuscles or granules present in neurons of the nervous system. These structures are found in the cytoplasm of the cell, and are located in specific parts of the neuron. They can be found especially in the soma or nucleus of the neuron and also in the dendrites, not being found in the neural axon.

Nissl bodies are considered to be clumps of rough endoplasmic reticulum.. In other words, they are structures formed by parallel cisterns with ribosomes (enzymatic structures made of ribosomal RNA) attached in a spiral, in which in addition polyribosomes can also be seen free. These bodies only appear in eukaryotic cells, that is, those that have a nucleus like neurons, and their function is the secretion of proteins.

They are also basophilic structures, characterized by the affinity and ease of staining by dyes. In these structures there a high concentration of both ribosomal and messenger RNA, the active ribosomes being bound to the latter.

They can be of different sizes and present in different numbers depending on the type of neuron. Those that are part of the autonomic nervous system ganglia tend to be small, while other large neurons tend to have larger Nissl bodies.

• You may be interested in: "Differences between DNA and RNA"

Function of these structures

Nissl bodies, as clumps of rough endoplasmic reticulum in which ribosomes are seen and in which both ribosomal and messenger RNA can be found, their main function is the synthesis and transport of proteins inside the cell. Specifically, the part of the Nissl bodies that have the most action when it comes to generating proteins to be used inside the cell are the free polyribosomes.

The proteins secreted by these bodies are essential for transmit nerve impulses between neurons, as well as participate in the generation of neurotransmitters.

In addition to this, the Nissl body has an important role in maintaining the health of the cell, by allow the regeneration of structures damaged by the activity of the neuron itself or by factors external.

Chromatolysis as a defense against neuronal damage

Nissl bodies can be damaged by possible injuries or pathologies. Neural damage such as that caused by trauma and disease They can cause damage to the axon.

The presence of damage to the axon causes the neuron to react by swelling and displacing the nucleus away from the injury. It also acts giving a response called chromatolysis, in which the Nissl bodies move from the neuronal cytoplasm to the injured area in order to repair it. The reorganization and regeneration of the axon is allowed, so that the functionality of the neuron is recovered, but while this occurs Nissl bodies dissolve. Fortunately, if the recovery of the neuron is achieved, chromatolysis ceases and the cytoplasm can recover and form new bodies.

This reaction can appear as we have said before injuries caused by trauma, but it has also been observed in various disorders. It is common to observe its appearance in neurodegenerative processes such as dementia due to Pick's disease or Alzheimer's (In fact, the changes in the cytoplasm that cause this event are often considered to be signs of neuronal degeneration, with which its occurrence can be a possible sign of danger), in encephalopathy of Wernicke's Wernicke-Korsakoff syndrome, diseases such as porphyria or some infectious diseases. It can also be observed in normative aging or in situations of great continuous stress for the individual.

Bibliographic references:

• Gomez, M. (2012). Psychobiology. CEDE Preparation Manual PIR.12. CEDE: Madrid-

• Ramon y Cajal, S. (2007). Histology of the nervous system of man and vertebrates. I take. Ministry of Health. Madrid.