ABSTRACT
Senescence has been defined as the endogenously controlled deteriorative changes that are natural causes of death in cells, tissues, organs, or organisms [1]. The differences from the term aging are well established, aging being all the degenerative changes that occur in time without reference to death as a consequence. Aging takes place during the entire life span of an organism, whereas senescence is considered the final developmental phase that culminates in death [1-3]. On the other hand, apoptosis or programmed cell death refers to an intracellular process by which the cell promotes a set of genetically determined self-destructive activities (including specific proteolysis and nuclear chromatin fragmentation) leading to its own death (i.e., death results from internal activity of the cell and not from ambient injuries). It is now accepted that many features of stress response and senescence at the cellular and molecular level are achieved through the operation of programmed cell death [4].
