Summary
Equidensitometric analytical techniques have been utilized in the study of synaptic ultrastructure. Selection of micrographs was made using three criteria; namely difficulty of interpretation of the micrographs, the need for quantitative investigation of them and the possibility that a greater degree of information might be extracted from them. The majority of junctions investigated were of E-PTA material, although conventionally prepared material was also analysed. Equidensitometry usingAgfacontour Professional film permitted three approaches: screen equidensities (substituting characteristic symbols for densities), line equidensities (lines joining points of equal density) and families of equidensities (where a number of line equidensities are assembled and printed together). Screen and line equidensities proved of most value in the profiles examined, the former for providing information regarding the substructure of paramembranous components (dense projections, cleft densities and postsynaptic densities) and the latter for clearly delineating and separating these components.
While these techniques cannot increase the information content inherent in the original electron micrographs, they aid interpretation for two reasons: the elimination of background noise in the line equidensity and the quantification of micrographs by the substitution of symbols for areas of equal density in screen equidensities. This report demonstrates the potential of these analytical procedures for synaptic ultrastructural studies, while at the same time obviating the necessity of the purchase of elaborate equipment.
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Nolan, T.M., Jones, D.G. Equidensitometric analytical techniques applied to the study of synaptic ultrastructure. J Neurocytol 3, 327–340 (1974). https://doi.org/10.1007/BF01097917
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DOI: https://doi.org/10.1007/BF01097917