A noticeable feature of mammalian skin surface lipids is the considerable variation in lipid and fatty acid compositions that exists between species (Nicolaides, Fu & Rice, 1968). The sebaceous lipids of oxen are characterized by the presence of relatively high levels of triglycerides, which, in contrast to those of other bovine tissues, contain a significant proportion (> 20%) of linoleic acid (Noble, Crouchman & Moore, 1974; Smith, Noble & Jenkinson, 1975; O'Kelly, Reich & Mills, 1980). The uniqueness of these highly unsaturated triglycerides has indicated possible roles in the chemical and biological defence systems of the skin surface for linoleic acid released by hydrolysis (Jenkinson, 1980). The skin surface triglycerides of calves do not attain the high levels of linoleic acid displayed by adults until 4–5 weeks after birth (Noble et al. 1975). It is, however, not known if a new-born calf compensates for this difference by an increase in sebum triglyceride concentration and output or, in view of the decreased availability of linoleic acid at this Stage, produces a sebum of widely different composition from the adult.
The Composition of Rat Skin Surface Lipids. Analysis of the Saponifiable and Nonsaponifiable Fractions.
