is an irreversible cell injury and eventual cell death due to pathological processes. It is an uncontrolled form of cell death involving swelling of organelles, plasma membrane rupture, and spillage of intracellular contents causing inflammation and tissue damage.
Necrosis
Differentiate necrosis from apoptosis.
Necrosis is uncontrolled and pathological, leading to inflammation, while apoptosis is a controlled, physiological process that does not elicit inflammation.
What are the nuclear changes associated with necrosis?
Pyknosis (nuclear shrinkage)
Karyorrhexis (nuclear fragmentation)
Karyolysis (nuclear fading or dissolution)
What are the cytoplasmic changes seen in necrosis under the microscope?
Cytoplasmic swelling
Increased eosinophilia
Vacuolation
Loss of cell boundaries
Name the sequence of events that occur in necrosis.
Cellular swelling → Organelle damage → Plasma membrane rupture → Leakage of cell contents → Inflammation
What organ is examined in this case and from what animal?
(P-04-0167)
The heart of a pig.
(Heart – P-04-0167) What condition was this pig diagnosed with that led to secondary necrotic changes in the heart?
Cholelithiasis
(Heart – P-04-0167) Describe the microscopic appearance of the cardiac muscle in this case.
Fragmentation of cardiac muscle fibers with loss of nuclei and presence of necrotic areas.
What indicates severe necrosis in cardiac tissue under microscopy?
(Heart – P-04-0167)
Extensive loss of nuclei and disintegration of muscle fiber structure.
(Heart – P-04-0167) What cellular components are present in between the muscle fibers?
White blood cells (WBCs) and red blood cells (RBCs).
(Heart – P-04-0167) Why are WBCs and RBCs found between necrotic cardiac fibers?
Due to inflammation and vascular leakage secondary to tissue necrosis.
(Heart – P-04-0167) What type of necrosis is typically seen in cardiac muscle?
Coagulative necrosis
D-99-0072
From what animal and organ was the sample taken?
Diaphragm skeletal muscle from a dog
(Skeletal Muscle – D-99-0072) What disease was the dog suspected to have?
Canine distemper
(Skeletal Muscle – D-99-0072) What was the gross finding noted during necropsy?
Paintbrush hemorrhage on the diaphragm muscles
(Skeletal Muscle – D-99-0072) Describe the microscopic changes seen in the skeletal muscle section.
Answer:
Necrosis with hyalinization of muscle segments
Inflammatory cell infiltration
Congestion
Enlarged diameter of necrotic fibers in cross section
(Skeletal Muscle – D-99-0072) What does hyalinization in necrotic muscle indicate?
Replacement of normal fibrillar structure by a homogeneous, glassy eosinophilic appearance due to protein denaturation.
