The elemental composition of keratohyalin granules from the interpapillary and papillary lingual epithelium and the oesophageal epithelium of the rat were studied by X-ray microanalysis in an EMMA-4 analytical electron microscope, equipped with an energy dispersive detector. A quantitative assay of the sulphur concentration in keratohyalin granules was performed, using a suitable sulphur standard. The results demonstrate that different types of keratohyalin granule have different compositions. Single granules - a type of keratohyalin granule present in both nuclei and cytoplasm of the epithelial cells - are rich in sulphur, having a content of 3.6-3.8%. Another type of keratohyalin granule - composite granules - contains a sulphur-rich component and a sulphur-poor component. The sulphur-poor component contains 0.8-1.4% sulphur. It is suggested that the sulphur-rich keratohyalin granules are involved in the deposition of the peripheral envelope protein of cornified cells.

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