Lipid composition of cohesive and desquamated corneocytes from mouse ear skin

An organ culture system has been used to examine differences in the lipid compositions of materials derived from cohesive and desquamated mouse ear stratum corneum. Within this culture system, skin explants display rates of cell replication and differentiation comparable to those observed in vivo for up to 2 weeks and, during this period, loosened or dishesive material accumulates at the surface. Lipid compositions were determined for both intact and loosened stratum corneum derived from cultured skin and also for freshly prepared stratum corneum. In all 3 cases, the profiles of the nonpolar lipids and the ceramides were essentially the same; some of the nonpolar lipids appeared to be of sebaceous origin. The only changes detected upon desquamation were reductions of cholesteryl sulfate and a second unidentified lipid of similar polarity. Cholesteryl sulfate constitutes 4-5% of the polar lipid in fresh stratum corneum or stratum corneum from organ culture. This is reduced to 0.4% in the desquamated material which accumulates in the culture system. The unidentified lipid decreases from 1-2% of the polar lipid in intact fresh or cultured stratum corneum to 0.1% in the desquamated material. The possible function of cholesteryl sulfate in corneocyte cohesion is discussed.