Born May 21, 1821, in Rothenburg, Bavaria; died there Apr. 13, 1908. German histologist.
Leydig was a professor at the universities of Tübingen (from 1857) and Bonn (from 1875). He worked out a structural and functional classification of tissues (1857). His main works dealt with the comparative histology of animal and human organs and tissues. He described the peculiar tissue found in the testes (interstitial cells of Leydig). Leydig also did several studies on invertebrate histology.