Adipocere (cire=wax) is a modification of putrefaction. In this, the fatty tissues of the body change into a substance known as adipocere. It is seen most commonly in bodies immersed in water or in damp, warm environment.
Mechanism: The change is due to the gradual hydrolysis and hydrogenation of pre-existing fats, such as olein, into higher fatty acids, which combine with calcium and ammonium ions to form insoluble soaps, which being acidic, inhibit putrefactive bacteria. Ultimately, the whole of the fat is converted into palmitic, oleic, stearic and hydroxystearic acid, together with some glycerol, and a mixture of these substances forms adipocere.
These form a matrix for remnants of tissue fibers, nerves and muscles. At the time of death, body fat contains, about half percent of fatty acids, but in adipocere they rise to 20% within a month and over 70% in three months. The process starts under the influence of intrinsic lipases, and is continued by the bacterial enzymes of the clostridia group, mainly CI. perfringens, as the bacteria produce lecithinase, which facilitates hydrolysis and hydrogenation. Water is essential for the bacterial and enzymatic processes involved in adipocere formation.
The water required for the hydrolysis is obtained mainly from the body tissues, which therefore become more and more dehydrated. In a body immersed in water, this fluid contributes to the hydrolysis of the subcutaneous fat, but the formation of it in deeper sites starts before the extraneous water enters the interior of the body. Water helps to remove glycerine which is formed during hydrloysis of the fats. Activation of lipid peroxidation is a significant component of the mechanism (Manulik, etal, 1999).
Adipocere is delayed by cold and hastened by heat. A warm, moist, anaerobic environment favors its formation. It is more frequently seen in females, the well-nourished mature newborn children, the obese and in corpses that have been submerged in water for a long period. It is also seen in buried bodies. Fetuses under seven months do not show this change. The bodies enclosed in a water-tight coffin for many years may be converted to adipocere even in the absence of external water.
It has a distinct offensive or sweetish smell, but during the early stages of its production, a penetrating ammoniacal odor is noticed. The smell remains in the clothing of those handling such bodies for several days. One’s olfactory sense rapidly becomes accustomed to the smell of adipocere, and one cannot smell it after about two minutes exposure.
The sense of smell rapidly returns after a few minutes in the open air. Fresh adipocere is soft, moist, whitish and translucent, but old samples are dry, hard, cracked, yellowish and brittle. It shows fragments of fibrous tissues and muscle in the fracture. It is inflammable and burns with a faint-yellow flame. It floats in water and dissolves in alcohol and ether.
Distribution : It forms in any site where fatty tissue is present. It is formed first in the subcutaneous tissues. The face, buttocks, breasts and abdomen are the usual sites. The limbs, chest wall, or other parts of the body may be affected, but sometimes the entire body is converted into adipocere. Fatty tissue between the fibers of skeletal muscle and in the myocardium and in the substance of the liver, kidney, etc., is also converted into adipocere.
The epidermis disappears as it forms, probably due to decomposition and shedding, and the dermis becomes darkened. Multiple whitish-grey, rounded outgrowths, varying from one to ten mm. in diameter are seen on the surface. They resemble molds but are protruding clusters of crystals from the underlying adipocere. In widespread adipocere, the soft tissues are markedly dry, unless there has been prolonged immersion in water.
Small muscles are dehydrated, and become very thin, and have a uniform greyish color. The depths of large muscles have a pink or red color in bodies with complete conversion of the fat to adipocere. The intestines and lungs are usually parchment-like in consistency and thinness. The liver is prominent and retains its shape. Histologically, the gross features of the organs can sometimes be appreciated, even though the cells are lacking. It may persist for decades, but finally either degenerates or is removed by mechanical forces or by animals.
Time Required for Adipocere Formation: In temperate countries, the shortest time for its formation is about three weeks in summer, when it occurs to a certain extent. Stiffening, hardening and swelling of the fat occurs over a period of months.
In most cases, the change is partial and irregular, but rarely the whole body may be affected. Complete conversion in an adult limb requires at least three to six months. In India, it has been observed to begin within 3 to 4 days. Adipocere may persist for years or decades.
(1) When the process involves the face, the features are well preserved, which help to establish the identity.
(2) The cause of death can be determined, because injuries are recognized.
(3) The time since death can be estimated.