Cell injury is defined as
A set of biochemical and morphological changes that occur when the
state of homeostasis is disturbed by adverse influence
CELL INJURY AND CELL DEATH

Reversible cell injury occurs when the injurious
agent is mild but persistent or severe but short lived.
In this type of injury the functional and morphologic
changes are reversible. With continuing damage,
there is irreversible injury, at which time the cell
cannot recover even with the removable of the
injurious agent i.e. it dies.
NOTE
injuries
Normal cell
Reversible changes (Degeneration)
injuries
Normal cell
Irreversible changes (Necrosis)
Section 2
Tissue and Cellular
Damage
Calcium Infiltration
Hydropic Degeneration
Reversible cell injury
Cloudy swelling
Gross appearance of cloudy swelling

Enlarged


Wheight
Pale

Early
stages:
granularity
degeneration——a fine granularity like
ground-glass in the cytoplasm.

Later stages: hydropic degeneration—
—clear vacuoles in the cytoplasm
Progressive dilatation of the swollen cell
Normal cell
Granularity change
Hydropic change
Reversible damage – cellular swelling
Cellular swelling (hydropic change or vacuolar degeneration): this is due to
paralysis of energy-dependent ion pumps of the plasma membrane. This leads to
influx of sodium (with water) into the cell and departure of potassium out. It is the
first manifestation of almost all forms of cell injury. Microscopically, there are clear
vacuoles (of water) within the cytoplasm.
Left Granularity change in kidney
Right Hydropic change
Swollen kidney tubules
Normal kidney tubules



Epithelial cells stain
evenly pink
(eosinophilic) in
cytoplasm, with
purple, basophilic,
nucleic acids
confined to the
nuclei
Apical surfaces are
ciliated
Interstitia not
infiltrated with
immune cells nor
congested with
proteins
Fatty change of liver
Left: Gross photograph .Center: HE Stain. Right: Oil Red-O Stain .
Fatty change: this is manifested by the appearance of lipid
vacuoles in the cytoplasm. It is principally encountered in cells
participating in fat metabolism such as hepatocytes; as in
alcoholic liver disease, malnutrition & total parenteral nutrition
Mechanism:


Impaired metabolism of fat
Excessive triglyceride into the
cell.
（From ROBBINS BASIC PATHOLOGY，2003）
3-Amyloid degeneration
General features: a ‘waxy substance’
(amyloid substance) composed
essentially of an abnormal protein is
deposited in the extracellular tissue,
particularly around the supporting fibers
of blood vessels and basement
membranes.
Detection:
Post-mortem organs:
Amyloid: deep brown
Lugol’s iodine
Normal tissue: yellow
Pathological effects
AMYLOID DEPOSITION
Pressure on adjacent cells
Atrophy
Blood vessels
Narrowing
Increased permeability
Transudation of protein
out of vessels