Research and exploration of the human brain and the structures that form part of it have been constant since ancient times. The neuron as the basic unit of the nervous system has been specially studied, using strategies such as using different spots to observe its structure.
The German neurologist Franz Nissl developed a stain based on dyes such as toluidine blue or cresil violet, and before its application was able to see 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 body: what are they?
Nissl bodies or ergastoplasm they are small structures in the shape 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 in particular in the soma or the nucleus of the neuron and also in the dendrites, not being in the neuronal axon.
Nissl bodies are considered clumps of rough endoplasmic reticulum. In other words, they are structures formed by cisterns parallel to ribosomes (enzymatic structures in ribosomal RNA) attached in a spiral, in which also those that can also be seen free of polyrribosomes. These bodies appear only in eukaryotic cells, that is, those which have a nucleus like neurons, and which have the function of secreting proteins.
They are also basophilic structures, characterized by affinity and ease of staining by dyes. In these structures there a high concentration of ribosomal and messenger RNA, The active ribosomes being attached to the latter.
They can have different sizes and be available in different quantities depending on the type of neuron. Those that are part of the autonomic nervous system ganglia tend to be small, while other large neurons generally benefit from large Nissl bodies.
Function of these structures
Nissl body, as conglomerates of rough endoplasmic reticulum in which ribosomes are observed and in which both ribosomal RNA and messenger RNA are found, their main function is the synthesis and transport of proteins inside the cell. Specifically, the part of Nissl’s body that has the most action when it comes to generating proteins for use inside the cell are the free polyribosomes.
The proteins secreted by these organisms are essential for transmit nerve impulses between neurons, In addition to participating in the generation of neurotransmitters.
In addition, Nissl’s body plays an important role in maintaining the health of the cell, 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 damage the axon.
The presence of axon damage causes the neuron to react by swelling and moving the nucleus away from the lesion. It also works by giving a response called chromatolysis, in which Nissl bodies move from the neuronal cytoplasm to the injured area in order to repair it. Reorganization and regeneration of the axon is allowed, so that the functionality of the neuron is recovered, but while it is happening Nissl’s bodies dissolve. Fortunately, if the neurons are recovered, chromatolysis ceases and the cytoplasm can recover and form new bodies.
This reaction can appear as we have said when dealing with injuries caused by trauma, but it has also been observed in various disorders. It is common to observe its onset in neurodegenerative processes such as dementia due to Pick’s disease or Alzheimer’s disease (in fact, the changes in the cytoplasm that cause this event are often taken as a sign neuronal degeneration, so its occurrence may be a possible danger sign), in Wernicke encephalopathy of Wernicke-Korsakoff syndrome, diseases such as porphyria or some infectious diseases. It can also be observed in normative aging or in the face of a situation of great continuous stress for the individual.
- Gómez, M. (2012). Psychobiology. CEDE PIR preparation manual 12. CEDE: Madrid-
- Ramón and Cajal, S. (2007). Histology of the nervous system of man and vertebrates. Tom i. Ministry of Health and Consumer Affairs. Madrid.