Golgi, Cajal, and the fine structure of the nervous system

Abstract

Towards the middle of the twentieth century, neuroanatomy was on the decline. It was revived by the development of two new methods. One was the Nauta-Gygax method, which selectively stained nerve fibers that had been caused to degenerate by experimental lesions. This allowed connections between various parts of the nervous system to be better determined. The second was electron microscopy, which allowed the structure of neurons and the synapses between them to be examined in detail, and eventually this led to a revival of the Golgi impregnation methods. This occurred in the 1970s because of the desire of electron microscopists to determine the origins of the neuronal profiles they encountered in electron micrographs of various parts of the central nervous system. Eventually this led to the development of Golgi/EM techniques, whereby individual impregnated neurons could first be characterized by light microscopy and then thin sectioned for detailed analyses. Examining the axon terminals of such impregnated neurons, especially those in the cerebral cortex, for the first time revealed details of intercellular connections and allowed neuronal circuits to be postulated. However, Golgi/EM had only a brief, but fruitful existence. It was soon superceded by intracellular filling techniques, which allowed the added dimension that the physiological properties of identified neurons could also be determined. KeywordsElectron microscopy; Golgi impregnations; synaptic connections Towards the middle of the twentieth century, anatomy, and especially neuroanatomy, was in the doldrums. In neuroanatomy a few basic stains were available for examining the central nervous system and most parts of it had been studied extensively using these stains. Some of the stains showed neurons in their entirety, while others only showed certain parts of neurons. To examine individual nerve cells in their entirety a number of variations on the Golgi impregnation methods were available, but the uncertainty about the quality and extent of the staining produced after tissue had been impregnated led to the Golgi methods being surrounded by mystique. In addition many thought that there was not much point in using the Golgi stain since all of the cell types had already been examined by Cajal and described in his 1911 volumes. Consequently only a handful of investigators used the Golgi stain. It was also possible to show entire cells using methylene blue staining on live tissue, but this never became a popular stain. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Most investigators preferred to use sectio...

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