Putrefaction or decomposition is the final stage following death, produced mainly by the action of bacterial enzymes, mostly anaerobic organisms derived from the bowel. Other enzymes are derived from fungi, such as penicillium and Aspergillus and sometimes from insects, which may be mature or in larval stage. The chief destructive bacterial agent is Cl. welchii, which causes marked haemolysis, liquefaction of post-mortem clots and of fresh thrombi and emboli, disintegration of tissue and gas formation in blood vessels and tissue spaces. The other organisms include Streptococci, Staphylococci, B. Proteus, B. Coli., B. aerogenes capsulatus, etc. Bacteria produce a large variety of enzymes and these breakdown the various tissues of the body. It begins immediately after death at the cellular level, which is not evident grossly. There is progressive breakdown of soft tissues and the alteration of their proteins, carbohydrates and fats. Organisms enter the tissues shortly after death, mainly from the alimentary canal, and less often through the respiratory tract or through an external skin wound. Because the protective agencies of the body are absent, the bacteria spread through the blood vessels using the proteins and carbohydrates of the blood as culture media.

Autolysis:
Soon after death, cell membranes become permeable and breakdown, with release of cytoplasm containing enzymes. The proteolytic, glycolytic and lipolytic action of ferments leads to autodigestion and disintegratio of organs, and occurs without bacterial influence.

The characteristic(3D) features of putrefaction are:

1. Discoloration-changes in the colour of the tissues,
2. Disfiguration-the evolution of gases in the tissues,
3. Dissolution-the liquefaction of tissues

Decomposition may differ from body to body, from environment to environment and from one part of the same body to another. Sometimes, one part of the body may be mummified, while he rest may show liquefying putrefaction.



Skeletonisation:
The time required for skeletonisation varies considerably. In the case of an exposed body, flies, maggots, ants, cockroaches, rats, dogs, jackals, vultures, etc., may reduce the body to a skeleton within a few days. When the body is in the water, it may be attacked by fishes, crabs, etc. which reduce the body to a skeleton in a few days. In an uncoffined body buried body, the lower temperature, the exclusion f air, absence of animal life, etc., markedly delay decomposition. The important factors are seasonal, climatic variation, the amount of soil water, the access of air, and the acidity or otherwise of the soil water. In India, an uncoffined buried body is reduced to a skeleton within about a year. Buried bones may decay at different rates, e.g. neutral soil may not destroy the skeleton at all. Acidic soil may cause decay in about 25 to 100 years. In bodies placed in airtight coffins, decay process may not occur for centuries. In a hot climate, bones on the ground surface may decay in 5 to 10 years. The protein content of the bones decomposes. As the bones contain largely inorganic material, they will crumble, rather than decompose. Flat bones and the bones of the infants and old, breakdown faster.

Internal phenomenon:
Internally, decomposition advances at the same rate as seen externally. As the blood decomposes, its colouring matter transudes into the tissues, which become uniformly red, the colour becomes darker and finally black. The viscera become greasy and softened. The softer the organ, the more blood it contains, and the nearer to the sources of bacteria, the more rapidly it putrefies. The organs composed of muscular tissue and those containing large amount of fibrous tissue resist putrefaction longer than the parenchymatous organs, which because of the contents at the time of death, decompose rapidly.

As a general rule, the organs show putrefactive changes in the following order. 1] Larynx and trachea. 2] stomach, intestines and spleen. 3] Liver, lungs. 4] Brain. 5] Heart. 6] Kidney, bladder, uterus. 7] Skin, muscle, tendon, 8] Bones.

Prostate: It resist putrefaction for a very long time.

Uterus: The virgin uterus is the last organ to putrefy. Gravid uterus or  soon after delivery, it rapidly putrefies.

Conditions affecting the rate of putrefaction:

A] External:

1. Temperature: Putrefaction begins above 10^oC and is optimum between 21^oC and 38^oC. A temperature increase of 10^oC usually doubles the rate of most chemical processes and reactions. It is arrested below 0^oC, and above 48^oC.
2. Moisture: For putrefaction moisture is necessary, and rapid drying of the body practically inhibits it.
3. Air: Free access of air hastens putrefaction, partly because the air conveys organisms to the body.
4. Clothing: Initially clothing hastens putrefaction by maintaining body temperature above that at which putrefactive organisms multiply for a longer period. If the clothing is tight as under the belts, suspenders, socks, tight-fitting undergarments, and boots, the putrefaction is slow, for it causes compression of the tissues, which drives out the blood from the part, and prevents the entry internal organisms. Clothes prevent the access of airborne organisms, flies, insects, etc., which destroy the tissues.
5. Manner of burial: If the body is buried soon after death, putrefaction is less. Putrefaction is rapid in a body buried in a  damp, marshy or shallow grave without clothes or coffin, because the body is exposed to constant changes of temperature. Putrefaction is delayed if body is buried in dry, sandy soil, or in a grave deeper than two metres, and when the body is covered and placed in a coffin because of exclusion of water, air and action of insects and animals. When a body is buried in lime, decomposition is delayed. Putrefaction is more rapid if changes of decomposition are already present at the time of burial.

B] Internal:

1. Age: The bodies of newborn children who have not been fed, decompose very slowly because the bodies are normally sterile. If the child has been fed before death, or if the surface of the body has been injured in any way, decomposition tends to take place with great rapidity. Bodies of children putrefy rapidly and of old people slowly.
2. Sex: Sex has no effect.
3. Condition of the body: Fat and flabby bodies putrefy quickly than lean bodies, due to larger amount of fluid in the tissues and excess fat, and greater retention of heat.
4. Cause of death: Bodies of persons dying from septicaemia, peritonitis, inflammatory and septic conditions, general anasarca, asphyxia, etc., decompose rapidly. Putrefaction is delayed after death due to wasting disease, anaemia, debility, poisoning by carbolic acid, zinc chloride, strychnine and chronic heavy metal poisoning, due to the preservative action of such substances on the tissues or their destructive or inhibitive action on organisms, which influence decomposition.
5. Mutilation: Bodies in which there are wounds, or which have suffered from other forms of violence before death, putrefy rapidly owing to the ease with which organisms gain access to the damaged tissues.


6. In advanced putrefaction, no opinion can be given as to the cause of death, except in cases of poisoning, fractures, firearm injuries, etc.

Putrefaction in water:
The rate of putrefaction is slower in water than in air. Putrefaction is more rapid in warm, fresh water than in cold, salt water. It is more rapid in stagnant water than in running water. Putrefaction is delayed when a body is lying in deep water and is well protected by clothing, while it is rapid in a body lying in water contaminated with sewage. As the submerged cadavers float face down with the head lower than the trunk, gaseous distension and post-mortem discolouration are first seen on the face and then spread to the neck, upper extremities, chest, abdomen and the lower extremities in that order. When the body is removed from the water, putrefaction is hastened as the tissues have absorbed much water. The epidermis of the hands and feet becomes swollen, bleached and wrinkled after immersion, and may be removed as a cast of the extremity, after 2 to 4 days. After several weeks in water, macerated flesh may be stripped from the body by the action of currents or the contact with the floating objects. Fish, crustacea [crabs, lobsters, shrimps, etc.] and water-rats in a sewer may destroy the body. Moulds may be located anywhere on the body, but generally are found only on the exposed surfaces.

 

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