Ultrastructural changes in cell death.

Necrotic cell death or necrosis is characterized morphologically by gain in cell volume, swelling of organelles, plasma membrane rupture and subsequent loss of intracellular contents.[12]

Although various alterations in organelles and cellular processes are considered in necrotic cell death, exact correlation between them is not yet drawn. Some of the changes considered include as follows.[234]

Mitochondrial alterations – uncoupling, production of reactive oxygen species (ROS), nitroxidative stress by nitric oxide or similar compounds and mitochondrial membrane permeabilization often controlled by cyclophilin D

Lysosomal changes – ROS production by Fenton reactions, lysosomal membrane permeabilization

Nuclear changes – hyperactivation of poly (ADP-ribose) polymerase-1 and concomitant hydrolysis of NAD+

Lipid degradation following activation of phospholipases, lipoxygenases and sphingomyelinases

Increase in the cytosolic concentration of calcium that results in mitochondrial overload and activation of noncaspase proteases calpains and cathepsins.

Following cell death, various morphologic changes occur within cell which can be initially noted at microscopic level, which later becomes manifested as gross changes.[5] With the help of transmission electron microscopy, the intracellular changes in the oral epithelial cell following cell death in postmortem tissues were demonstrated.

At 0–2 h – The cell was intact with no changes in cytoplasmic membrane and cellular organelles [Figure 1a–c]

Figure 1

(a) High power showing intact cell Junction (CJ) (98000). (b) Intact nucleus (N), mitochondria (Mt), Golgi apparaturs (G) and glycogen particles (Gly). (c) No changes found in nucleus (N), rough endoplasmic reticululm (RER) (49000)

At 12th h – The epithelial cell showed nuclear, cytoplasmic and mitochondrial vacuolation, while the cell junction was found to be intact [Figure 2a and b]

Figure 2

(a) Nuclear (Nu) and cytoplasmic (Cyt) vacuolatin (Vac) and intact cell junction (CJ) (13,000). (b) Mitochondrial vacuolation (Mt Vac) (30,000)

At 24th h – The cell showed increased cytoplasmic vacuolation, intact nucleus and intercellular junction, while there was enlargement of mitochondria and endoplasmic reticulum [Figure 3a and b]

Figure 3

(a) Cell showing vacuolation (Vac) and intact intercellular junction (ICJ) (9300). (b) Cell showing nucleus (Nu) enlarged mitochondria (Mt) and endoplasmic reticulum (ER) (18,500)

At 36th h – Intracellular organelles were not discernible [Figure 4].

Figure 4

Intracellular details not discernible

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