The original research material upon which the discovery of Alzheimer's disease was based is being made available online by optics specialist Carl Zeiss Ltd., providing pathologists with their first opportunity to view rediscovered slides of human brain tissue from patients observed by German psychiatrist and neuropathologist Alois Alzheimer. In 1906 -- using a Carl Zeiss jug-handle microscope -- Alzheimer prepared over 250 slides of human brain tissue from a female A jug-handle microscope manufactured by Carl Zeiss Jena from approximately 1898 to 1910. Alzheimer's microscope was fitted with compensator oculars and, among other objectives, a 1/12 NA 1.30 oil-immersion objective. The microscope shown, model 47238, was made in 1906. (Photo courtesy Zeiss). patient; he published his findings in 1907. That year, he began to treat a male patient and prepared more than 150 slides, after the patient's death, in 1910. Both lots of material were rediscovered in basements of the University of Munich after a search organized by Manuel Graeber, a neuropathology professor at Imperial College London. Well-preserved and of high technical quality, all of the more than 400 specimens are being scanned and saved as virtual slides using a Zeiss Mirax digital histology system. The Mirax produces a 'virtual slide' for each specimen in just two minutes, providing the same field of view as normal microscope eyepieces "without the ergonomic penalty from long periods of use," Zeiss said. The slides are being released progressively. Apart from their unique scientific value, the importance of the rediscovery of the slides is that they put an end to lingering doubts about whether Alzheimer's first patient, a 51-year-old woman, suffered from a rare metabolic disorder called metachromatic leukodystrophy rather than the disease named after him, Zeiss said in a statement. An image of part of Alois Alzheimer's first slide showing the two classic pathological signs of Alzheimer's disease: amyloid plaques and neurofibrillary tangles. (Photo courtesy Zeiss) "However," the company said, "Graeber says the rediscovered slides show no evidence of this, but the cortex does exhibit the two classic pathological signs of Alzheimer's -- amyloid plaques and neurofibrillary tangles." Pathologists worldwide may now judge for themselves at: www.zeiss.de/alzheimer