در تک سلولی ها ان طوری که در یوکاریوت ها هست وجود نداره ! این هم منبع حرف هایم !! ( cell death and differentiation journal ) .
راجع به دلیل تکاملیش هم هنوز نظر خاصی ندارم . سوال جالبیه !
Programmed cell death: sine qua non of a multicellular state
The origin of eukaryotes and the advent of multicellularity are
momentous evolutionary transitions that involved invention of
several fundamentally new functional systems.The eukar-
yotic chromatin remodeling machinery,the cell cycle regula-
tion systems,the nuclear envelope,the cytoskeleton,and the
programmed cell death(PCD,or apoptosis) apparatus all are
such major eukaryotic innovations,which do not appear to
have direct prokaryotic predecessors.
Although bacterial cells commit suicide under certain circumstances,for
example,during fruiting body formationin Myxobacteria,
these mechanisms do not appear to be essential for the
survival of prokaryotes in general and their molecular build-up
seems to be unrelated to that of eukaryotic apoptotic
machinery.