Allen's main corpus of work related to sex hormones. He was the first to discover the hormone estrogen in 1922, and also discovered progesterone in 1929. He was also the first to synthesize progesterone in 1934. Allen's work on sex hormones helped to revolutionize the understanding of reproduction and sexual development.
The Alluring World of Edgar Allen: An Exciting English Quiz on the Father of Anatomy and Physiology