Apoptosis

Apoptosis

1. APOPTOSIS By.Dentaltutor.in

2. a form of ‘coordinated and internally programmed cell death’ pathway of cell death that is induced by a tightly regulated suicide program in which cells destined to die activate enzymes capable of degrading the cells' own nuclear DNA and nuclear and cytoplasmic proteins Apoptosis is responsible for mediating cell death in a wide variety of physiologic and pathologic processes www.dentaltutor.in APOPTOSIS

3. www.dentaltutor.in APOPTOSIS

4. The plasma membrane of the apoptotic cell remains intact, but the membrane is altered in such a way that the cell and its fragments become avid targets for phagocytes. The dead cell is rapidly cleared before its contents have leaked out, and therefore cell death by this pathway does not elicit an inflammatory reaction in the host Thus, apoptosis differs from necrosis However, apoptosis and necrosis sometimes coexist, and apoptosis induced by some pathologic stimuli may progress to necrosis www.dentaltutor.in APOPTOSIS

5. www.dentaltutor.in Apoptosis V/S Necrosis

6. Organised cell destruction in sculpting of tissues during development of embryo . Physiologic involution of cells in hormone-dependent tissues Endometrial shedding during mensuration Regression of lactating breast after withdrawal of breast-feeding. Normal cell destruction followed by replacement proliferation such as in intestinal epithelium. Involution of the thymus in early age. www.dentaltutor.in Physiologic Processes

7. Cell death in tumours exposed to chemotherapeutic agents . Cell death by cytotoxic T cells in immune mechanisms such as in graft-versus-host disease and rejection reactions. Progressive depletion of CD4+T cells in the pathogenesis of AIDS. Cell death in viral infections e.g. viral hepatitis. Pathologic atrophy of organs and tissues on withdrawal of stimuli e.g. prostatic atrophy after orchiectomy , atrophy of kidney or salivary gland on obstruction of ureter or ducts, respectively. Cell death in response to injurious agents involved in causation of necrosis e.g. radiation, hypoxia and mild thermal injury. In degenerative diseases of CNS e.g. in Alzheimer’s disease, Parkinson’s disease, and chronic infective dementias www.dentaltutor.in Pathologic Processes

8. A,Apoptosis in the skin in an immune-mediated reaction B,High power of apoptotic cell in live in immune-mediated hepatic cell injury. www.dentaltutor.in

9. Ultrastructural changes Margination or progressive loss of nuclear chromatin Focal rupture of the nuclear membrane Breakdown of the plasmalemma . Development of flocculent densities in mitochondria. Changes in the nucleus Pyknosis : condensation of chromatin of chromatin and shrinkage of the nucleus. Karyorrhexis : fragmentation of the nucleus. Karyolysis : dissolution of the nucleus. www.dentaltutor.in Recognition of Cell death Normal Pyknosis Karyorrhexis Karyolysis

10. Changes in cytoplasm staining Positive staining with vital dyes such as Trepan blue which reflects abnormal membrane permeability. Opacification : denaturation of proteins lead to aggregation with resultant opacification of the cytoplasm. Eosinophilia : exposure of basic amino groups results in increased affinity for acidic dyes such as eosin. Biochemical changes Release of K + by dead cells. Release of enzymes into the blood. e. g. increased plasma levels of creatine kinases , lactic dehydrogenase and aspartate aminotransferase . Release of protein or protein breakdown products into the blood. www.dentaltutor.in Recognition of Cell death

11. Postmortem change Tissues in dead body can be distinguished from necrosis by being diffuse and not associated with inflammatory response . Autolysis Digestion of cell by enzymes released from lysosome ; occurs after cell dies. www.dentaltutor.in Recognition of Cell death

12. Robbinson's basic pathology 8 ed Harsh Mohan - Textbook of Pathology 6th Ed. Color atlas of pathology www.dentaltutor.in References

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