New findings on the proteins of sebaceous glands

In order to understand the distribution and concentration of proteins with -SH groups or S-S linkages in sebaceous cells during differentiation and holocrine secretion of sebaceous glands, skin specimens from the inner side of ears of New Zealand white rabbits were examined histochemically and ultrastructurally. DACM (N-[7-dimethylamino-4-methyl-3-coumarinyl] maleimide) staining method showed that proteins containing -SH groups were present in the cells (cytoplasm and nuclei) in all layers from the peripheral to the terminally differentiated cells of sebaceous glands and that proteins containing S-S linkages were present in the terminally differentiated cells and their pyknotic nuclei but not in the peripheral and differentiating cells of sebaceous glands. Lipid droplets in all sebaceous cells contained neither -SH groups nor S-S linkages. Ultrastructurally, the terminally differentiated cells were very electron dense and seemed to be abruptly formed from the differentiating cells that were producing lipid droplets. These findings indicate that the conversion of -SH groups to S-S linkages of proteins also occurs in sebaceous glands as in epidermis and hair.