Search results
Results from the WOW.Com Content Network
A cell undergoing apoptosis shows a series of characteristic morphological changes. Early alterations include: Cell shrinkage and rounding occur because of the retraction of lamellipodia and the breakdown of the proteinaceous cytoskeleton by caspases. [56] The cytoplasm appears dense, and the organelles appear tightly packed. [citation needed]
Apoptosis is the programmed cell death of superfluous or potentially harmful cells in the body. It is an energy-dependent process mediated by proteolytic enzymes called caspases, which trigger cell death through the cleaving of specific proteins in the cytoplasm and nucleus. [13] The dying cells shrink and condense into apoptotic bodies.
Overview of signal transduction pathways involved in apoptosis. Cell death is the event of a biological cell ceasing to carry out its functions. This may be the result of the natural process of old cells dying and being replaced by new ones, as in programmed cell death, or may result from factors such as diseases, localized injury, or the death of the organism of which the cells are part.
Programmed cell death (PCD; sometimes referred to as cellular suicide [1]) is the death of a cell as a result of events inside of a cell, such as apoptosis or autophagy. [ 2 ] [ 3 ] PCD is carried out in a biological process , which usually confers advantage during an organism's lifecycle .
Involution is the shrinking or return of an organ to a former size. At a cellular level, involution is characterized by the process of proteolysis of the basement membrane (basal lamina), leading to epithelial regression and apoptosis, with accompanying stromal fibrosis.
Pyknosis (from Ancient Greek πυκνός meaning "thick, closed or condensed") is also observed in the maturation of erythrocytes (a red blood cell) and the neutrophil (a type of white blood cell). The maturing metarubricyte (a stage in RBC maturation) will condense its nucleus before expelling it to become a reticulocyte .
Affected cells then proceed to blebbing, and this is followed by pyknosis, in which nuclear shrinkage transpires. [21] In the final step of this pathway cell nuclei are dissolved into the cytoplasm, which is referred to as karyolysis. [21] The second pathway is a secondary form of necrosis that is shown to occur after apoptosis and budding. [21]
The presence of apoptotic "sub-G 1 cells" can also be detected in cells pre-fixed in ethanol but not after fixation in the crosslinking fixatives such as formaldehyde. The late-S and G 2 apoptotic cells may not be detected with this approach because their fractional DNA content may overlap with that of the non-apoptotic G 1 cells. [ 17 ]