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Pathological Changes of Chronic Occurrence of Minamata Disease (Moderate)

brain10.GIF (14119 bytes)

Takeuchi & Eto, 1977

A calcarine area of a chronic onset case running the course of 11 years (KU No. 5583, 65-year-old male), not less than 50% of neurons are lost, which is classed as grade 3. Klüver-Barreera's staining, X 150.

Loss of not less than 50% of granule cells (grade 3). KU No. 5583. Klüver-Barrera's staining, X 60.

Electron micrograph of a biopsy specimen of the sural nerve of a chronic onset case (41-year-old female). The regenerating unit contains the Schwann cell nucleus, two small mylinated fibers ad one collapsed axon, X3200

Typical neuropathological findings in methylmercury poisoning were first described by Hunter-Russell (1954). Minamata disease exhibits a variety of neuropathological features, from severe changes at the early stage to mild changes.

The pronounced changes in the white matter in the brains were usually unobservable in the first three years following poisoning but emerged (4-6 years) and became widespread after 10 years.

Preferential, localized neuropatho-logic disintegration in the brain occurred mainly in the calcarine contex, precentral and postcentral cortices and central portion of the cerebellum in typical cases.

The changes were characterised by tissues coarseness, sclerosis was observed in some cases, and the later stages were characterised by thinning of the myelim.

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