Mammalian stratum corneum contains physiologic lipid thermal transitions

Using a new high-sensitivity differential scanning calorimeter, capable of very slow scanning rates and large sample volumes, we examined the thermal transitions in neonatal mouse stratum corneum. Both physiological and supraphysiological transitions were found in intact tissue that were displaced on cooling and obliterated by solvent treatment establishing them as lipids. Physiologic peaks were encountered in lipid extracts from the same tissues. With heating and cooling recycling we found a novel effect of thermal "fractionation" of the peaks into discrete subfractions that appeared to correspond roughly the the number of bands found on thin-layer chromatography of the lipid extracts.