Chemistry of Melanin. IV. Electron Micrography of Natural Melanins.

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Abstract
Melanin granules were obtained by differential centrifugation from pigmented tissues and characterized with the phase contrast and electron microscopes. Granules from the S-91 and Harding-Passey transplantable mouse melanomas were elliptical particles, the major axes ranging from 0.30 [mu]-0-45 [mu] and the minor axes from 0.25 [mu]-0.40 [mu]. Granules from the ciliary body, choroid, and iris of cattle eyes varied from circular to elliptical outline, 0.30 [mu]-2.00 [mu] across. Melanin granules from colored human skin were observed as rods and spheres. The rods varied in size from 0.10 [mu] X 0.40 [mu]-0.18 [mu] X 0.60 [mu]. The pigmented globules appeared to have diams. between 0.20 [mu] and 0.30 [mu]. The melanin-containing pseudoglobulin from the S-91 melanoma consisted of melanin granules unchanged in shape or size with respect to the granules obtained by centrifugation. All micrographs were uniformly dense across the images of the melanin granules and conclusions with respect to internal structure could not be drawn.
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