Lxi.—lipids of the Skin

The process by which the normal active cells of the stratum germinativum become the hard, scaly, cornified cells of the stratum corneum involves some extremely interesting chemical changes in the cell constituents. The most apparent change is that which takes place in the protein in the formation of keratin. That the fatty constituents of the cell also undergo marked changes during keratinization is suggested when histologic studies are interpreted in the light of modern concepts concerning lipids in their relation to physiologic activity. As was pointed out in an earlier review of skin lipids,1the nature of the fatty substances in a tissue may reflect in a general way its physiologic activity. Thus the lipids of an inactive tissue such as the panniculus adiposus are almost entirely made up of neutral fat, that is, simple esters of fatty acids with glycerin, while those of active tissues such