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electrically excitableintermediate metabolismslightly variable in volumeresists infectioncan healdoes not denaturecytoplasm and nucleoplasm are fluidnot after histology, histochemistry orelectron microscopyno metabolismswellsbecomes infectedcannot healdenaturesboth precipitateTable 1. These are very significant differences.Analysis of histology, histochemistry and electron microscopyOptimally, one would like to study the cell biology of the nervous system in the livingintact animal (Table 1). Attempts have been made using reflected light, and confocalmicroscopy, to examine brains and spinal cords in situ, but this has not yet been donesuccessfully, except with sciatic nerves. The probable reasons are that the tissues are tootranslucent and the membranes do not reflect much light.However, the next best approach is to separate the tissue using as little energy aspossible, and examine it in an environment as closely as possible mimicking its naturalextracellular fluid.The following minimum steps occur in histology;(a) the animal is restrained, and then killed, preferably with minimum pain;(b) the tissue undergoes agonal changes;(c) the nervous tissue is excised;(d) the part of the tissue is separated;(e) the cells or tissues are characterised optically;(f) they are photographed.These steps may be examined individually. Killing an animal changes its biochemistrygrossly. For example, its blood carbon dioxide, phosphate, lactate, and potassium ion5