Cellular senescence

Apoptosis (from ) is a form of programmed cell death that occurs in multicellular organisms and in some eukaryotic, single-celled microorganisms such as yeast. Biochemical events lead to characteristic cell changes (morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, DNA fragmentation, and mRNA decay. The average adult human loses 50 to 70 billion cells each day to apoptosis. For the average human child between 8 and 14 years old, each day the approximate loss is 20 to 30 billion cells.

progression of biochemical and morphological phases and events that occur in a cell during successive cell replication or nuclear replication events

thumb| Scanning electron micrograph of an Apoptosis|apoptotic HeLa cell. Zeiss Merlin HR-SEM. thumb|Multiphoton fluorescence image of cultured HeLa cells with a fluorescent protein targeted to the Golgi apparatus (orange), microtubules (green) and counterstained for DNA (cyan). Nikon RTS2000MP custom laser scanning microscope. thumb|Immunofluorescence image of HeLa cells grown in tissue culture and stained with antibody to [[actin in green, vimentin in red and DNA in blue]] thumb|Immunofluorescence of HeLa cells showing [[microtubules in green, mitochondria in yellow, nucleoli in red and nucle

number of times a normal human cell population will divide until cell division stops; (in culture) phenomenon, when fibroblasts can reach a maximum of 50 cell divisions before becoming senescent

biological process

thumb|300px|Apoptosis Karyorrhexis (from Greek κάρυον karyon, "kernel, seed, nucleus," and ῥῆξις rhexis, "bursting") is the destructive fragmentation of the cell nucleus that occurs in a dying cell. It is characterized by the breakdown of the nuclear envelope and the dispersal of condensed chromatin into the cytoplasm. The process is usually preceded by pyknosis (irreversible chromatin condensation) and followed by karyolysis (enzymatic dissolution of chromatin). It may occur during programmed cell death (apoptosis), cellular senescence, or necrosis.

phenomenon characterized by the cessation of cell division

thumb|right|350px|Morphological characteristics of karyolysis and other forms of nuclear destruction. Karyolysis (from Greek κάρυον karyon—"kernel, seed, or nucleus", and λύσις lysis from λύειν lyein, "to separate") is the complete dissolution of chromatin in a dying cell caused by enzymatic degradation through endonucleases. Following karyolysis, the entire cell typically stains uniformly with eosin. Karyolysis represents the final step in the process of necrosis, a form of cellular injury in which living tissue undergoes irreversible damage through premature cell death. Unlike apoptosis, whi

thumb|275px|Apoptosis

variety of changes of stress that a cell suffers due to external as well as internal environmental changes

cell line

thumb|WI-38 cells (Left: in high density. Right: in low density) WI-38 is a diploid human cell line composed of fibroblasts derived from lung tissue of a 3-month-gestation female fetus. The fetus came from a legal abortion performed in Sweden in 1962. The cell line was isolated by Leonard Hayflick the same year, and has been used extensively in scientific research, with applications ranging from developing important theories in molecular biology and aging to the production of most human virus vaccines. The uses of this cell line in human virus vaccine production is estimated to have saved the

gene causing apoptosis

lineage of cells that evades senescence and continues dividing