Page 36 - Concise Pathology for Exam Preparation ( PDFDrive )

1 Cell Injury and Cell Death 21

the phosphatidylserine so that it is expressed on the outer membrane and is easily
recognized by the macrophage.
(b) Secretion of soluble factors by apoptotic cells, eg, thrombospondin, which recruit
macrophages.
(c) Coating of apoptotic cells by natural antibodies and proteins of the complement
system, which are easily recognized by macrophage receptors.

Q. Differentiate between apoptosis and necrosis.
Ans. Differences between apoptosis and necrosis are shown in Table 1.7.

TABLE 1.7. Differences between apoptosis and necrosis
Features Apoptosis Necrosis
Definition Programmed and coordinated cell death, Spectrum of morphologic changes that
which eliminates unwanted/harmful follow cell death in living tissue,
cells or removes cells damaged be- largely resulting from the progressive
yond repair degradative action of enzymes on le-
thally injured cells
Causes May be physiological or pathological Always pathological, eg, hypoxia, toxins
Involves Single or small groups of cells Large groups of cells
Inflammation Absent Present
Cellular change Cell shrinkage Cell swelling
Cell membrane Bleb formation Membrane disruption
Nucleus Chromatin condensation followed by Nuclear pyknosis, karyolysis and kary-
fragmentation orrhexis
Removal of cell Phagocytosis of apoptotic bodies by Enzymatic digestion or phagocytosis of
macrophages cell debris by macrophages
Lysosomes/other organelles Intact Hydrolytic enzyme release due to rup-
ture
Mechanism Genetically coordinated Due to ATP depletion, free radicals,
mitochondrial damage, etc.
Agarose gel electrophoresis Stepladder DNA pattern Diffuse DNA pattern

Q. Enumerate the disorders associated with apoptosis.
Ans.

1. Disorders associated with decreased apoptosis: cancer, autoimmunity
2. Disorders associated with increased apoptosis:
(a) Neurodegenerative diseases (Alzheimer, Huntington, Parkinson)
(b) Ischaemic injury in stroke and myocardial infarction
(c) Death of virus-infected cells as in AIDS

Q. Enumerate the steps in diagnosis of apoptosis.
Ans. Diagnosis of apoptosis:

1. Stepladder pattern on agarose gel electrophoresis
2. Terminal deoxynucleotidyl transferase biotin-dUTP nick end labelling (TUNEL) tech-
nique for in vivo detection
3. H&E, Feulgen and acridine orange staining of apoptotic cells
4. Measurement of cytosolic cytochrome c and activated caspase
5. Expression of phosphatidylserine on the outer leaflet of the plasma membrane by apop-
totic cells enables their recognition by using the dye Annexin V

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