Lecture 6: Postmortem Changes

What are postmortem changes the result of?

autolysis (decomposition)

What changes occur prior to death and take minutes to hours to weeks to develop?

antemortem

What is autolysis?

the decomposition of cells which occurs due to loss of cellular integrity or breakdown of cells which occurs after death

How is autolysis minimized?

performing a post mortem evaluation and collection of tissues as close to the time of death as possible and fixing tissues in a fixative such as formalin at the time of collection

What tissues will autolyze quickly?

intestinal mucosa, brain, and spinal cord

What tissues has the ability to contract after death which can lead to artifacts?

striated muscle

When does rigor mortis set in and how long does it persist?

1-6 hours after death and persists for 1-2 days thereafter

Why should you cool a carcass and not freeze it?

cooling of the carcass slows autolysis, but freezing destroys tissue architecture and cellular integrity due to ice crystal formation

How can abundant adipose tissue in overweight or obeswe animals or thick wool cause rapidly progressing autolysis?

heat retention in the body longer

Why do febrile animals autolyze faster?

higher body temp

How can microbial flora affect post mortem decomposition?

gas production causing bloat of tissues and organs which can result in post mortem prolapse of the rectum, uterus, or protopsis of the eyes, even diaphragm can rupture

What are the variables in post mortem decomposition?

• tissue

• type of animal

• cause of death

• environmental temp

• body temp

• microbial flora

What is liver mortis/hypostatic congestion?

the gravitational pooling of blood after death which results in discoloration of tissues (can also be present in organs like the lungs)

True or false: postmortem lesions are differentiable from antemortem lesions.

false: postmortem lesions can mask antemortem lesions