Sphingomyelin profiling service provides data on all individual molecular species. Sphingomyelins (SM) constitute an important class of phospholipids in the membranes of most eukaryotic cells. In mammalian tissues, SM usually constitute 2–15% of the total organ phospholipid, but certain tissues such as brain, peripheral nervous tissue and ocular lenses have even higher SM contents, especially in some nerve cell axons. Sphingomyelin (or ceramide phosphorylcholine) consists of a ceramide unit with a phosphorylcholine moiety attached. Sphingomyelin does not appear to occur in plants or fungi, which produce ceramide phosphorylinositol instead, or in bacteria with rare exceptions, and its evolutionary significance is a matter for speculation.