Histochemical staining for
aluminum, using Solochrome azurine or
Morin, provided a rapid, simple and reliable means of identifying areas and structures of the brain of interest for closer scrutiny by X-ray microanalysis in patients with
amyotrophic lateral sclerosis and
parkinsonism-
dementia of Guam. Neuronal perikarya, dendritic processes, and the walls of some cerebral vessels were
aluminum positive by Solochrome azurine staining. In some cases, the deposition of
aluminum was rather diffuse, particularly in the white matter. Fluorescent localization of
aluminum using
Morin was equally sensitive and specific, but provided less morphological detail than Solochrome azurine. Confirmation of histochemical detection of
aluminum was achieved by examining adjacent tissue sections using wavelength-dispersive spectrometry coupled to a computer-controlled electron beam X-ray microprobe. Although the minimum detectable limits for
aluminum by these histochemical procedures are unknown, the lower detection limit of our X-ray microanalytical technique is 10-100 ppm dry weight. Solochrome and
Morin staining, as verified by X-ray microanalysis, afford a useful and reliable means of surveying multiple anatomical regions for
aluminum deposition in naturally occurring and experimentally induced
neurodegenerative disorders.