Non-accidental death seems to occur either when cells have completed a fixed number of division cycles (~60; the Hayflick limit) or at some earlier (programmed) stage, as occurs in limb development to separate the digits. It is still unclear whether death at this limit is a consequence of accumulated errors or a result of telomere shortening or some other ‘timing’ programme. Transformed cells appear to have escaped the Hayflick limit and can divide indefinitely. See apoptosis.
Subjects: Medicine and Health.