Necrosis and Apoptosis

Difference between Necrosis and Apoptosis

Whenever there is damage to the cell, the organism tries to repair it. If not, the cell dies. It can die in two ways: necrosis, always associated with a pathological cause, and apoptosis, pathological or physiological. Necrosis: This form of cell death occurs only when lysosomal enzymes digest the cell. Inside the cell, there are cisterns (lysosomes) full of substances (enzymes), which are responsible for the cell’s digestion (autolysis), just as the stomach is responsible for our digestion (Jo et al. 2019). In necrosis, inflammation is observed since the remains of cell membranes are recognized by the defense cells as antigens (invaders).

Coagulative necrosis: Coagulation of proteins in the cytoplasm occurs, and the cells are blurred and unclear. The cells die when observed under a microscope, but their basic structure remains intact. Usually, there is no cell membrane disruption, and the nucleus disappears (karyolysis) (Jo et al. 2019). It is not always a fast process and is associated with a lack of oxygen in the tissue (ischemia). It just does not occur in cerebral ischemia because neurons do not have enough intracellular proteins to maintain the cell’s structure. The tissue looks like blanched, boiled meat (also called ghost tissue). Liquefactive Necrosis: Usually associated with infection by microbes that attract defense cells to the injury site (Jo et al. 2019). During battle (inflammation), many cells are destroyed, eaten (phagocytosed), and digested, giving necrotic tissue a soft, shapeless consistency, often composed of pus. It can also occur in cerebral ischemia, but we still don’t know how it happens.

Apoptosis: This modality is dictated as programmed cell death or cell death not followed by autolysis. Often, for dozens of reasons, the cells in our body need to die so that there are no more severe complications, as in the case of an invasion of the cell by a parasite or a genetic mutation, which would eventually lead to cancer (Jo et al. 2019). In situations where cell death is necessary, the organism uses a very efficient method for this, Apoptosis. Unlike necrosis, Apoptosis is an orderly process, where the leading causes of necrosis are: Renewal: When tissue needs to be replaced or renewed. Too much Apoptosis occurs during the embryonic stage (Morula, Blastula, and Gastrula), where many embryo structures need to involute to continue the formation process (Jo et al. 2019). Infection: When a microbe (mainly virus) invades one of our cells (intracellular), sometimes the body cannot eliminate it, activating the self-destruct mechanism and killing the host along with the parasite.

References

Jo, M., Kim, T. H., Seol, D. W., Esplen, J. E., Dorko, K., Billiar, T. R., & Strom, S. C. (2019). Apoptosis induced in normal human hepatocytes by tumor necrosis factor-related apoptosis-inducing ligand. Nature medicine, 6(5), 64-67.