The Intimate Relationship Of The Nervous System

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Seeing is believing: The intimate relationship between neuroanatomical understanding and microscopical technique

Microscopical techniques have been an irreplaceable source of our knowledge about the nervous system. Not only have they provided clear evidence supporting the variety of hypotheses but also deepened our understanding by allowing the researchers to make valid links between the components of the nervous system and their functions. In this paper, I wish to explore the development of these techniques and how they allowed the investigators to arrive to the certain conclusions and dismiss theories created by their predecessors. However, microscopical techniques always had their limitations, which at first impeded scientific
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This staining technique continued to be used by many scientists including Forel and Ramón y Cajal, who eventually dismissed the Nerve Net theories presented by both Deiter and Golgi. Due to the lack of evidence of the anastomoses between nerve cell processes, it became clear that each nerve cell neighbours with other cells, but it is not merged with them to form a network (Contact Theory of Forel) (Clarke and O’Malley, 1968). Although the Golgi technique was widely applicable, its limits were soon discovered; this method randomly stained small numbers of neurons and the staining was not always complete. So when examining retinal neurones, there was no certainty if all subclasses of cells were labelled (Morgan et al., 2005).
Vittorio Marchi was a pioneer of degeneration techniques. At first, the myelin sheath degeneration technique suggested by him was considered to have an enormous potential, but as the method involved staining breakdown products of myelin, some pathways were not stained, especially if they were not myelinated well enough. In 1913, Nissil stated that soma of the neurons in the principal nuclei of the thalamus degenerate if the cortex is damaged. He used dyes such as cresyl violet and methylene blue, which revealed the changes occurring in soma of the cell with damaged axons (Cowan,
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