Sulphur in different types of keratohyalin granules: a quantitative assay by X-ray microanalysis.

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 36-3-8%. Another type of keratohyalin granule composite granulescontains 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.