Small bodies, about half a micron in diameter, and later referred to under the name of 'mitochondria' were detected under the light microscope as early as 1894.

While working at Rockefeller University in the 1930s and 1940s he used the electron microscope to make images of cells which deepened the scientific understanding of cellular structure and function. Albert Claude (24 August 1898 – 22 May 1983) was a Belgian biologist who shared the Nobel Prize in Physiology or Medicine in 1974 with Christian de Duve and George Emil Palade.

For his discoveries concerning the structural and functional organization of cells Claude received the 1974 Nobel Prize in Physiology or Medicine which he shared with his student George Palade and Christian de Duve. He studied engineering and then medicine (at the University of Liège Belgium).