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Biological Sciences: X-ray Diffraction and Fine Structural Studies of Crystals in the Malpighian Tubules of Silkworms


THE Malpighian tubules of insects serve as an excretory organ and also as a site for the storage of waste products. In the silkworm (Bombyx mori), these tubules are filled with bire-fringent crystals (Fig. 1). Early workers observed particles in Malpighian tubules and noted their appearance in the lumen during the moulting cycle1,2. They tentively identified the particles as urates, carbonates or calcium oxalate3,4. Using powder X-ray diffraction, we have established that the crystals are calcium oxalate monohydrate.

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    Grassé, P. P., and Lesperon, K., CR Soc. Biol., 122, 1013 (1936).

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    Noël, R., and Tahir, E., Arch. Anat. Microsc., 25, 587 (1929).

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    Wigglesworth, V. B., The Principles of Insect Physiology (Dutton, New York, 1965).

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    Plotnikov, W., Z. Wiss. Zool., 76, 333 (1904).

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    Pobequin, T., Ann. Sci. Nat. Bot., Ser. 11, 4, 1 (1943).

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    Ohnishi, E., Takahashi, S. Y., Sonobe, H., and Hayashi, T., Science, 160, 783 (1968).

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    Pohl, R. W., Toxicon, 3, 67 (1965).

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