Two distinct neuronal inclusions occur in Parkinson's disease. The Lewy body is the diagnostic hallmark and is recognized by its eosinophilic body and unstained halo. It can be found in specific regions of the nervous system, where its frequency, size, shape, and structure differ. Large neurons of the dorsal vagal nucleus and sympathetic ganglia often contain particularly large quantities of Lewy-body-like matter. It consists of filament in the outer part and electron dense material in the core, the outer part staining with silver and with antibodies to neurofilament and tubulin. The pale body is restricted to the substantia nigra and locus ceruleus. It does not react with conventional stains, silver, or neurofilament antibodies, and has a homogeneous structure with a granular and vesicular surface texture. It contains sparse granular matter, vacuoles, and filaments, surrounded by melanin. The Lewy body and pale body may be juxtaposed or contiguous in some cells, but their distinct appearances and structures indicate that they are separate inclusions.

The electron-microscopical appearance of a Rathke's cleft cyst is described. The cyst lining is seen to consist predominantly of secretory columnar epithelium, both ciliated and non-ciliated. There are also epidermoid cells occurring singly or in squamae. The histogenesis of Rathke's cleft cysts, in relation to craniopharyngiomas, is discussed.

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