The histologist Sigmund Freud and the biology of intracellular motility.

Sigmund Freud, the acclaimed founder of psychoanalysis, invested nine years of his early scientific effort investigating animal histology, cell biology and basic neuroscience prior to concentrating on human nervous and mental disorders. Through his histological studies Freud provided coherent evidence suggesting that the protoplasm consists of a contractile fibrillary network, the present-day cytoskeleton; he was one of the original founders of the fibrillary theory on the structure of the protoplasm. Concerning the biology of the cell nucleus, Freud appears to have been the first author who documented movements of nucleoli in nerve cells, a phenomenon presently referred to as nuclear rotation. In certain instances, Freud's observations antedate later views by more than half a century and are important to our current understanding of cell structure and basic processes of intracellular motility.