Authors observe how, in particular situations, able to modify the extracellular habitat, the epithelial tissue can present a phenomenon named “modulation”, distinguished by detachment of cellular elements and by acquisition of a clear amoeboid activity, by consequence the tissue changes its usual morphology, maintaining its primitive nature too. Moreover they maintain that such a phenomenon is not limited to the epithelial tissue, but it may be verified in any kind of tissue with the characters of a “histiocytary transformation”, able, in particular environment conditions, to regain potentialities inherent in its metabolic make-up, which were latent due to the process of cellular differentiation.