C24 Phytosphingosine (t18:0/24:0) is a phytoceramide, which is a family of sphingolipids found in the intestine, kidney, and extracellular spaces of the stratum corneum of the mammalian epidermis. C24 Phytosphingosine (t18:0/24:0) is composed of a phytosphingosine backbone amine-linked to a C24 fatty acid chain. It has been used with other ceramides to create stratum corneum substitutes to study percutaneous penetration and psoriasis in vitro. In a stratum corneum model of healthy skin, the incorporation of long-chain-containing phytoceramides, such as C24 phytosphingosine (t18:0/24:0), increases permeability of the membrane in comparison with incorporation of dihydroceramides.