In most animals, the main wax production is associated with the sebaceous glands of the skin.
Most of these glands are associated with hair follicles, but there are also related structures on the
eyelids termed Meibomian glands. Sebaceous glands secrete mainly non-polar lipids in the form of
sebum onto the skin surface, where they are easily recovered for analysis. Although relatively few
species have been studied in real detail, it is evident that a wide range of lipid classes are present
and that these vary greatly in amount and nature between species (there may also be variationwith age). The composition of human sebum differs appreciably from that of other species,
especially in the high content of triacylglycerols and in fatty acid composition. Some typical data
are listed in Table 3.