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 has been especially 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 upon its application he 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 or ergastoplasma They 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, but are not found in the neuronal axon.
Nissl bodies are considered clumps of rough endoplasmic reticulum In other words, these are structures formed by parallel cisternae with ribosomes (enzymatic structures made of ribosomal RNA) attached in a spiral, in which free polyribosomes can also be seen. These bodies only appear in eukaryotic cells, that is, those that have a nucleus like neurons, and their function is the secretion of proteins.
These are also basophilic structures, characterized by the affinity and ease of staining by dyes. In these structures there is a high concentration of both ribosomal and messenger RNA with the active ribosomes attached to the latter.
They can have different sizes and occur in different quantities depending on the type of neuron. Those that are part of the ganglia of the autonomic nervous system tend to be small in size, while other large neurons usually have larger Nissl bodies.
Function of these structures
Nissl bodies, as conglomerates of rough endoplasmic reticulum in which ribosomes are observed 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 plays the most role in 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 participating in the generation of neurotransmitters.
In addition to this, the Nissl body has an important role in maintaining the health of the cell, by allowing the regeneration of structures damaged by the neuron’s own activity or by external factors.
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 moving the nucleus away from the injury. It also acts by giving a response called chromatolysis, in which 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, in 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 usually considered a sign of neuronal degeneration, so its occurrence may be a possible sign. danger), in Wernicke’s encephalopathy of Wernicke-Korsakoff syndrome, diseases such as porphyria or some infectious diseases. It can also be observed in normative aging or in situations of continued great stress for the individual.
