Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Marker degradation is a three-step synthetic route in steroid chemistry developed by American chemist Russell Earl Marker in 1938 40. It is used for the production of cortisone and mammalian sex hormones (progesterone, estradiol, etc.) from plant steroids, and established Mexico as a world center for steroid production in the years immediately after World War II. The discovery of the Marker degradation allowed the production of substantial quantities of steroid hormones for the first time, and was fundamental in the development of the contraceptive pill and corticosteroid anti- inflammatory drugs. In 1999, the American Chemical Society and the Sociedad Química de México named the route as a National Historic Chemical Landmark.