Proli_feration of the smooth muscle cells (SMC), the cells of the adventitia, and the endothelial and epithelial cells forming blood vessels and viscera play an important role in the pathogenesis of many diseases. In atherosclerosis proliferation of vascular SMC occurs in the plaque, and in hypertension polyploidization of SMC is enhanced . There are various hypotheses on the causes of cell division: denudation of the vascular endothelium , the effect of growth factors , damage to the muscular layer [8,13], activation of tumor precursors , denervation [9,10], and an increase of functional loads . In many cases cell proliferation proves to be a mechanism of general adaptation directed toward overcoming unfavorable conditions. Enhanced activity of the blood vessels as well as of the walls of the urinary bladder and uterus causes an increase of SMC proliferation necessary in order to compensate for the increased load. On the other hand, a decreased functional load reduces SMC proliferation in these organs . The migration of cells of the seminiferous tubule promotes their proliferation under culturing conditions, and the subsequent reirmervation by the sympathetic ganglia suppresses SMC proliferation . Any processes directed toward normalizing the functional activity of the tissues diminish SMC proliferation.