Secretin
Secretin was the first hormone to be identified. In 1902, William Bayliss and Ernest Starling were studying how the nervous system controls the process of digestion. It was known that the pancreas secreted digestive juices in response to the passage of food (chyme) through the pyloric sphincter into the duodenum. They discovered (by cutting all the nerves to the pancreas in their experimental animals) that this process was not, in fact, governed by the nervous system. They determined that a substance secreted by the intestinal lining stimulates the pancreas after being transported via the bloodstream. They named this intestinal secretion "secretin". Secretin was the first such "chemical messenger" identified. This type of substance is now called a hormone, a term coined by Bayliss in 1905.
Progynon
Progynon was an orally active formulation of estrogen that was developed by Adolf Butenandt at Schering and introduced in Germany in 1928. It was reportedly the first sex hormone product and hence also the first estrogen product to be introduced for medical use. Progynon was originally an ovarian or placental extract, but Schering soon switched for economic reasons to using the urine of women who were in late pregnancy. This form of Progynon was essentially the same product as Emmenin, which was developed by James Collip at Ayerst and introduced in Canada in 1930 (and in the in 1934).