Desmosterol: An intermediate in the synthesis of cholesterol.Triparanol: Antilipemic agent with high ophthalmic toxicity. According to Merck Index, 11th ed, the compound was withdrawn from the market in 1962 because of its association with the formation of irreversible cataracts.Sterols: Steroids with a hydroxyl group at C-3 and most of the skeleton of cholestane. Additional carbon atoms may be present in the side chain. (IUPAC Steroid Nomenclature, 1987)Phytosterols: A class of organic compounds known as STEROLS or STEROIDS derived from plants.Oxidoreductases Acting on CH-CH Group Donors: A subclass of enzymes which includes all dehydrogenases acting on carbon-carbon bonds. This enzyme group includes all the enzymes that introduce double bonds into substrates by direct dehydrogenation of carbon-carbon single bonds.Sitosterols: A family of sterols commonly found in plants and plant oils. Alpha-, beta-, and gamma-isomers have been characterized.Lanosterol: A triterpene that derives from the chair-boat-chair-boat folding of 2,3-oxidosqualene. It is metabolized to CHOLESTEROL and CUCURBITACINS.StigmasterolCholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Dehydrocholesterols: Cholesterol derivatives having an additional double bond in any position. 24-Dehydrocholesterol is DESMOSTEROL. The other most prevalent dehydrocholesterol is the 7-isomer. This compound is a precursor of cholesterol and of vitamin D3.Cholestanes: Derivatives of the saturated steroid cholestane with methyl groups at C-18 and C-19 and an iso-octyl side chain at C-17.SqualeneChromosomes, Human, 19-20: The short, metacentric human chromosomes, called group F in the human chromosome classification. This group consists of chromosome pairs 19 and 20.