Skip to Main Content



The study of endocrinology is often traced to the work of Charles-Edouard Brown-Sequard, a 19th-century French-American physiologist best known for his investigations of the nervous system. In 1889, Brown-Sequard began to experiment with an elixir containing an extract fromĀ guinea pig and dog testes. He claimed that the extract had rejuvenating effects, including increased stamina and strength. Although Brown-Sequard was largely ridiculed at the time, his elixir study provided an early understanding of the nature of testosterone, the hormone that leads to the development of male secondary sex characteristics.

The term hormone was first used by scientists Ernest Starling and William Bayliss in 1902, when they discovered secretin, the hormone that stimulates pancreatic secretion. The scientists went on to define a hormone as a chemical that is produced by an organ, is released in small amounts into the bloodstream, and is then transported to another organ to perform a specific task.

Throughout the 20th century, scientific understanding of the endocrine system and hormones developed at a rapid pace. Today, the term endocrinology encompasses a broad range of scientific and medical studies.

Related Professions