[The present position of the theory of regeneration]

A distinction is made among three periods in the history of the theory of regeneration: macroscopic, microscopic, and ultramicroscopic. Processes of regeneration are not restricted to cell division (mitosis, amitosis) but occur also at intracellular level through renewal of ultrastructural cell components. Intracellular regeneration is universal and is associated with all organs, without any exception, whereas cellular regeneration is lacking in some organs (CNS, myocardium). Physiological and reparative regeneration are considered to be one coherent process with different mechanisms and manifestations.