Apoptosis nuclear chromatin condensation

Apoptosis is characterized by nuclear chromatin condensation, cytoplasmic shrinking, a dilated endoplasmic reticulum, membrane blebbing, and the formation of apoptotic bodies. Programmed cell death is clean, quick, and involves a predictable sequence of structural changes that cause a cell to shrink and to be rapidly digested by macrophages or neighboring cells. 

Another morphological assay of apoptosis is done with acridine orange, a nuclear staining that reveals chromatin condensation under light and fluorescent microscope. 

Thermal and chemical cellular stresses result in the rapid disappearance of ubiquitinated histones [258,259]. The levels of ubiquitinated histones drops precipitously after human tumor cells are treated with proteasome inhibitors [260,261]. Deubiquitination of uH2A also occurs during apoptosis, with its lose coinciding with nuclear pyknosis and chromatin condensation [262,263]. 

Fig. 15.1. Schematic representation of morphologic changes in a cell during apoptosis. On reception of an apoptotic signal, an adhesive cell (a) begins to become rounded (b) and the nuclear DNA condenses (c). The DNA is fragmented and the nucleus begins to break down into discrete chromatin bodies (d). Finally, the cell disintegrates into several vesicles (apoptotic bodies) (e), which are phagocytozed by neighboring cells (f).

Currently, there are many methods available for determining cell death by apoptosis in cell cultures and tissues. These methods are based essentially on changes that occur in apoptotic cells. During apoptosis, several phenomena can be observed, such as DNA fragmentation, chromatin condensation, nuclear fragmentation, cytoplasm acidification, cytochrome c release from the mitochondria, exposure of intracellular phospholipids and the activation and breakdown of proteins. These apoptotic phenomena can be detected by direct or indirect methods, on cell populations or on individual cells that are representative of a population. The main principles used by the different detection methods are ... 

Apoptotic features have been occasionally found in other cardiac disorders in humans [128-131] and experimental models [107, 132-135]. Takemura et al. [135] studied Fas-induced cardiomyocyte apoptosis by electron microscopy, and found extensive condensation of nuclear chromatin and shriveled cytoplasm, fragmented nuclei, and apoptotic bodies. Apoptotic features correlated with positivity for TUNEL and caspase-3. A distinct morphological feature was the abundance of lipid-like structures in the cytoplasm at the early phase and high incidence of plasma membrane rupture at the later phase. Apoptotic bodies were observed to be phagocytosed by neighboring cardiomyocytes. 

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