Lecture 6: Cell Injury- postmortem changes

What are post-mortem changes the result of, and do they have pathological significance?

- Result of autolysis (self-digestion/decomposition).

- Not a pathologic process → therefore, not considered lesions.

- Antemortem changes occur prior to death and take minutes-hours-weeks to develop.

How can autolysis be minimized during post-mortem evaluation?

- Perform necropsy and tissue collection as close to time of death as possible.

- Immediately fix tissues in formalin to halt autolysis.

- Fixatives cross-link proteins, stabilizing cells and preventing further breakdown.

Which tissues autolyze the fastest and which resist autolysis the longest?

Fast autolysis: intestinal mucosa, brain, spinal cord.

Slow autolysis: skeletal muscle (retains integrity longer).

What post-mortem artifact can occur in skeletal muscle due to its contractile ability?

Rigor mortis - commences 1-6 hours after death, persists for 1-2 days thereafter.

How does the animal's body composition influence the rate of post-mortem decomposition?

Animals with abundant adipose tissue (overweight/obese) or thick wool retain heat longer → accelerates autolysis.

How does cause of death affect post-mortem decomposition rate?

Certain causes (e.g., septicemia, hyperthermia) may accelerate decomposition, though effect is variable.

How does environmental temperature impact autolysis?

Cool temperatures slow autolysis.

Freezing is not recommended → ice crystals destroy tissue architecture and cellular integrity.

Hot environments accelerate autolysis.

How does body temperature at time of death affect autolysis?

Febrile animals autolyze faster due to elevated core temperature.

What role do microbial flora play in post-mortem changes?

Produce gas → bloat of tissues/organs.

Can cause post-mortem prolapse (rectum, uterus) or proptosis of eyes.

Gas buildup can even rupture the diaphragm.

Post-mortem change cause? Significance?

Autolysis; not pathologic, not lesions.

Minimize autolysis how?

Fast necropsy; fix in formalin (protein cross-link).

Fastest autolysis tissues?

Intestinal mucosa, brain, spinal cord.

Slowest autolysis tissue? Artifact?

Skeletal muscle; rigor mortis (1-6h start, lasts 1-2d).

Body composition effect?

Fat/wool → retain heat → faster autolysis.

Cause of death effect?

Certain causes (e.g., sepsis, hyperthermia) → faster breakdown.

Environmental temp effect?

Cool slows, hot speeds; freezing damages tissue.

Body temp effect?

Fever → faster autolysis.

Microbial flora effect?

Gas → bloat, prolapse, proptosis, diaphragm rupture.