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Cell Death in Normal and Malignant Tissues

1975; Elsevier BV; Linguagem: Inglês

10.1016/s0065-230x(08)60971-9

2162-5557

E.H. Cooper, A.J. Bedford, Tom Kenny,

Cell death mechanisms and regulation

Cell loss from tumors is a major factor controlling their growth. An equation attempting to act as a model for growth must include suitable expressions to allow for tumor cell loss. This chapter proposes the concept that tumors contain two populations—dividing and nondividing tumor cells—and the fraction of proliferating cells is being termed as the "growth fraction." In normal renewal tissue in steady state, the whole of cell production is matched by an equal cell loss. The reasons for the loss of cells from the proliferating pool can be classified into a number of general headings; sometimes these causes act alone, but usually they act in concert. The intrinsic, physical displacement, and extrinsic factors operate continuously in varying degrees from the earliest stages of tumor recognition. This chapter reviews cell death in normal and malignant tissues. The moment of death coincides with the loss of a certain percentage of the cell organization or the interrelation among vital cell organelles. The difficulty that faces the experimentalist is the phase of irreversible injury prior to cell death. The moment and mode of death and the necrosis of the cell corpse may show widely different patterns according to the nature of the cell and the mode of its death. Electron microscopy can be helpful in suggesting the likely sequence that is leading to the death of the cells, and it is particularly valuable for studying the death of cells when they appear discretely in well-vascularized parts of a tumor. Time-lapse microcinematography provides a continuous record of the behavior and movements of cells in vitro. The advantage of using time-lapse cinematography to study cell death is that the whole sequence of changes is permanently recorded.