Necrosis Vs Apoptosis

Q. Mention differences between necrosis and apoptosis.

Ans : Though both necrosis and apoptosis are events of cell death, they do differ in various ways. The differences can be observed under following parameters :

a) Cell Size
The cell is enlarged (swelling) in necrosis whereas the cell is reduced (shrinkage) in apoptosis.

b) Fate of Nucleus
In necrosis, nucleus undergoes series of changes like pyknosis ( irreversible condensation of chromatin in the nucleus of a cell ) , karyorrhexis (fragmentation of nucleus) and karyolysis (complete dissolution of the chromatin of a dying cell due to the enzymatic degradation). But, in Apoptosis, nucleus undergoes fragmentation into nucleosome size fragments

c) Plasma Membrane
The plasma membrane is disrupted and is full of leakages in case of necrosis but, it is intact in cells undergoing apoptosis. Only the orientation of lipids in plasma membrane is altered in apoptosis.

d) Cellular contents
Due to ruptured plasma membrane, cellular contents undergo digestion and may leak out of the cell in necrosis. But, the cellular contents are intact in case of apoptosis. However, they may be released in apoptotic bodies.

e) Adjacent inflammation
There is no any adjacent inflammation seen in apoptosis whereas adjacent inflammation can be seen in necrosis.

f) Physiologic or pathologic role
Apoptosis is often physiologic but necrosis is always pathologic.

Necrosis : Definition, Types and Examples

Q. Define Necrosis. Enlist its types with an example of each.

Ans: Necrosis is the type of cell death that is associated with loss of membrane integrity and leakage of cellular contents culminating in dissolution of cells, largely resulting from the degradative action of enzymes on lethally injured cells.

Types of Necrosis:
i) Coagulative Necrosis
- underlying tissue architecture is preserved,

- affected tissues take on a firm texture

- characteristic of infarcts in all of the solid organs except the brain

ii) Liquefactive Necrosis
- seen in focal bacterial or fungal (occasionally) infections

- the dead cells are digested completely, transforming the tissue into a liquid viscous mass

- seen often in hypoxic death of cells within CNS

iii) Caseous Necrosis (Caseous = Cheese like)
- Encountered most often in foci of tubercular infection

- friable yellow white appearance of the necrotic region

- area of caseous necrosis is often enclosed within a distinctive inflammatory border; this appearance is characteristic of a focus of inflammation known as a granuloma


iv) Fat Necrosis
- focal areas of fat destruction

- seen in Acute Pancreatitis

- grossly visible chalky white areas can be seen

v) Fibrinoid Necrosis
- special form of necrosis visible by light microscopy

- usually in immune reactions in which complexes of antigens and antibodies are deposited in the walls of arteries.

- a bright pink and amorphous appearance on H&E preparations called fibrinoid (fibrin-like) by pathologists

- seen in  immunologically mediated diseases (e.g. polyarteritis nodosa)

vi) Gangrenous Necrosis
- mostly the affected organ has lost its blood supply and has undergone coagulative necrosis involving multiple tissue layers

- When bacterial infection is superimposed, coagulative necrosis is modified by the liquefactive action of the bacteria and the attracted leukocytes (resulting in so-called wet gangrene)

- e.g. necrosis of a limb (mostly lower)

World Oral Health Day - 20th March 2017 - Live Mouth Smart

Poster for Oral Health Awareness : World Oral Health Day 2017 , Designed By: Raman Dhungel, BPKIHS,Dharan, Nepal.

FDI World Dental Federation (Federation Dentaire Internationale), has decided to celebrate 20th March 2017 as the world oral health day with a theme "Live mouth Smart".

The first World Oral Health Day was celebrated on 20th March 2013 by FDI World Dental Federation. Since then, every year , on 20th March it is celebrated across the globe by organising various campaigns and programs to raise Oral health awareness.

The themes for World Oral Health Day till date are:
2013: Healthy Teeth for Healthy Life
2014: Brush for a Healthy Mouth!
2015: Smile For Life!
2016: It all Starts Here. Healthy Mouth. Healthy Body
2017: Live Mouth Smart.


Good oral health leads to good overall health.
Share the message of World Oral Health Day and spread Oral Health Awareness.

MCQs on Oral Histology - Dentin Part 5

# During the formation of primary teeth:
A. Enamel forms more cervically than dentin
B. Enamel forms faster than dentin
C. Dentin forms faster than enamel
D. Processes of their cells remain in content with each other

# Matrix vesicles :
A. Are found in mantle dentin
B. Contain collagen
C. Produce alkaline phosphatase
D. Inhibit mineralization

# Transmission of stimulus across dentin is:
A. Direct activation of nerve endings
B. Correlated with the innervation density of the dentin
C. Stimulus induced fluid flow
D. There is no transmission of stimulus across dentin

# During hydrodynamic theory movement of fluids in dentinal tubules cause:
A. Movement of odontoblasts
B. Touch the nerves of the pulp to cause pain
C. Minimum effect on odontoblast
D. Stimulation of odontoblastic process


# Which of the areas of the tooth is most sensitive during cavity preparation :
A. Enamel (anterior teeth)
B. Enamel (posterior teeth)
C. Dentin
D. Dentinoenamel junction

# Matrix vesicles play important role in the mineralization of :
A. Dentin
B. Enamel
C. Pulp
D. Periodontal ligament

# False statement regarding interglobular dentin is :
A. The term interglobular dentin refers to organic matrix that remains unmineralized because the mineralising globules fail to coalesce
B. This occurs most often in the circumpulpal dentin just below the mantle dentin
C. Where the pattern of mineralization is likely to be appositional than globular
D. Large areas of interglobular dentin is a characteristic feature of childhood hypophosphatasia

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