Short Video Showing the changes of a human eye after death over time

Immediate Postmortem Changes

"Immediate postmortem changes" or "rapid changes after death" relate to the cessation of bodily functions, including the respiratory, circulatory, and nervous systems. These changes are specifically the "signs of death" or "indications of death." In brief, death is considered to have occurred when the vital functions of the body have irreversibly ceased.

Respiration completely stops after death resulting in loss of respiratory movements and breathing sounds. The feather test and mirror test are a couple of traditional tests used to confirm this. However, these tests are quite unreliable.

Circulatory stoppage results in a loss of pulse, which can also be confirmed by a flat electrocardiogram (ECG) in a hospital setting. The absence of respiratory and cardiac sounds on auscultation over 5 minutes indicates a sign of death as advocated by expert clinicians. The finding of the break-up of the columns of blood in the retinal blood vessels (retinal vascular segmentation) on ophthalmoscopy confirms the stoppage of circulation and is one of the earliest indications of death.

Cessation of nervous system functions results in the loss of sensory and motor functions and reflexes. The muscles begin to become flaccid with a loss of tone. Pupils also dilate as a result of this. A flat electroencephalogram (EEG) confirms the loss of electrical activity in the brain in a hospital setting.

Early Postmortem Changes

Three early postmortem changes occur while the body is still in the fresh stage before the breakdown of soft tissues, namely algor mortis, livor mortis, and rigor mortis, which are of forensic significance.

The eye changes during the early postmortem period include corneal turbidity/opacity and tache noire formation. The intraocular tension progressively falls to nil about 2 hours after death, although this is disputable.

Algor mortis

is the postmortem cooling of body temperature until it equalizes the temperature of the surrounding environment. The rate of cooling lags initially, then becomes linear before slowing down again as it approaches the ambient temperature, giving a sigmoid-shaped curve when graphically represented. The ambient temperature is a critical factor that affects the rate of postmortem cooling of the body. Postmortem cooling of the body continues for about 6 hours after death, and the rate of cooling is primarily dependent on the difference in body temperature at the time of death and the temperature of its surroundings. The rate of cooling will hasten in a body immersed in water, a naked body, and a thin body. The rate of cooling will be slower in a well-clothed body and an obese body. A prudent forensic pathologist will not estimate the time since death based on the single criterion of algor mortis. The rate of postmortem cooling of the body is affected by multiple variables.

Livor mortis

also known as postmortem hypostasis or postmortem lividity, is a passive process of blood accumulating within the blood vessels in the dependent parts of the body as a result of gravity, causing a discoloration of the skin that varies from pink to dark purplish. It begins to be apparent about an hour after death, is well-formed in about 3 to 4 hours after death, and gets fixed in about 6 to 8 hours after death. However, it is worth noting that the timing of livor mortis is highly variable. Hemolysis leads to the fixation of lividity. Once fixed, lividity does not shift its distribution when the position of the body changes. The dermal manifestation of postmortem lividity may be absent in the severely anemic or those who have died of severe hemorrhage. It may not be apparent in the dark-skinned.

Livor mortis requires differentiation from a contusion or bruise, which occurs due to blood vessel rupture from blunt force impact and exsanguination of blood into the surrounding tissues.

Rigor mortis (postmortem rigidity)

is the stiffening of the muscles of the corpse due to the depletion of adenosine triphosphate (ATP) after death with the subsequent build-up of lactate in muscle tissue resulting in an inability to release the actin-myosin bond. This postmortem muscle change appreciated grossly follows the initial phase of primary flaccidity of muscles and is itself followed by the secondary flaccidity of muscles that coincides with the beginning of putrefactive changes. The process of rigor mortis uniformly involves all muscles of the body. However, it is first apparent generally in smaller muscles such as the jaw and the eyelids due to quicker depletion of ATP relative to larger muscles in the trunk and limbs. Rigor mortis occurs in both voluntary and involuntary muscles, including the cardiac muscle. It is first evident in the facial muscles at 1 to 4 hours after death. The gelling of the muscle proteins is apparent as muscle stiffening in about 6 hours after death in the rest of the muscles and is complete about 12 hours after death. This rigidity of the muscles lasts for about another 12 hours or so. The body then returns to a flaccid state after the enzymatic breakdown of actin and myosin binding sites. The rate at which rigor mortis passes off will be rapid in a hot environment as the onset of putrefaction is hastened in such an environment. Cold temperatures lengthen the duration of rigor.

In brief, postmortem changes in the muscles include:

Primary flaccidity of the muscles

The rigidity of the muscles (rigor mortis)

Secondary flaccidity of the muscles

Rigor mortis of the arrector pili muscle attached to the base of a hair follicle is also responsible for the phenomenon of cutis anserina (cutis anserine), otherwise known as postmortem goosebumps. Rigor mortis needs to be distinguished from cadaveric spasm/instantaneous rigor, which is an immediate contraction of a small group of muscles at the instance of death, seen in scenarios of violent death like in the case of drowning.

Late Postmortem Changes

Decomposition

Two mechanisms are involved in decomposition: autolysis and putrefaction. Although decomposition begins soon after death through autolysis, the macroscopic changes brought about by decomposition become apparent much later when putrefaction occurs.

Autolysis is a process that occurs due to leakage of hydrolytic cellular enzymes from cells after death. The changes that occur in this process are mainly on a microscopic rather than a macroscopic level. Internally, autolytic changes are most prominent in the pancreas and other organs with a high concentration of cellular enzymes. In comparison, the prostate and the non-gravid uterus take a longer duration of time to decompose.

The leakage of cellular contents also leads to a suitable environment for microbes such as bacteria, fungi, and protozoa, normally present in the human microbiota, to grow and degrade surrounding tissues, which is known as the process of putrefaction.

Unlike autolytic changes, putrefactive changes are visible on a macroscopic level as discoloration of the skin or bloating of body parts such as the face, abdomen, breast, and scrotum. It can appear in various forms, such as putrefactive fluids and putrefactive gases.

Stages of Decomposition

There are five stages of decomposition, namely fresh, bloated, active decay, advanced decay, and skeletal stage. These stages may occur simultaneously in different parts of the same corpse, and it may be difficult for a forensic pathologist to label the state of the corpse with a single stage.

The fresh stage

is the immediate period following death in which autolysis occurs. Algor mortis, livor mortis, and rigor mortis are apparent in this stage.

The earliest external sign of putrefaction is the greenish discoloration of the skin of the anterior abdominal wall in the right iliac fossa region. In this region of the abdomen, the caecum, loaded with semi-solid intestinal content and commensal gut bacteria, lies quite superficial. This greenish discoloration of the skin results from the formation of sulfhemoglobin facilitated by the commensal intestinal bacteria that invade the tissues after death. This skin discoloration in the right iliac fossa region appears about 18 hours after death. In temperate climates, this greening may first appear 2 to 3 days after death. The ambient temperature affects the speed of onset of putrefaction and its rate of progression.

The blowflies (Calliphoridae) and flesh flies (Sarcophagidae) are often the first insects attracted to a dead body. In brief, the invasion of the body by flies and the life cycle of flies (oviposition, hatching of eggs, feeding activity of larvae or maggots, the transformation of maggots to adult flies) coincide primarily with the bloated and decay stages of decomposition. The flies may even be attracted to a dead body towards the end of the fresh stage.

Bloated stage

body parts, including organs and soft tissues, swelling due to the accumulation of putrefactive gases or other decompositional products from the putrefaction process. It usually starts in the abdomen and then slowly affects other parts, including the face, breasts, and genitals. Also, during this stage, skin changes occur, such as blisters and slippage. Skin slippage at the extremities is known as degloving. Moreover, the phenomenon of marbling is also present during this stage, where blood vessels are visible on the skin as greenish-black streaks and eventually results in skin discoloration ranging from green to black. These postmortem changes are apparent in about 24 to 48 hours after death.

Active decay

is a stage where putrefaction accelerates after bloating. Postmortem purging where putrefactive body fluids become forced out of body orifices is observable during this stage of decomposition. The detachment of hair or hair sloughing and black discoloration of ruptured skin are seen.

Advanced decay

also called black putrefaction or late decay, is a stage where bones begin to get exposed, and the body assumes a "caved in" appearance. Degradation-resistant tissue such as hair (although already sloughed) and cartilage are spared up to this stage.

The skeletal stage

also called dry remains stage or skeletonization, begins when bone exposure is extensive, but the bone is yet to break down. The remaining dried skin, cartilage, and tendons are minimal in this stage. Decomposition significantly slows down at this stage, and it takes years or decades for the skeletal remains to disintegrate.

The literature also reports differential decomposition involving mummification or adipocere formation.

Mummification

Mummification results from tissue desiccation and is a phenomenon that occurs when the corpse is in an environment that is hot and dry. The skin of the corpse becomes dark, dry, and appears leathery in appearance.Overall the body appears parched; this preserves the corpse for a more extended period. It can occur to the corpse as a whole or in localized areas such as the extremities or the tongue.

Adipocere Formation

Adipocere is a yellowish to a gray-colored waxy substance that can preserve the corpse as a whole or some parts of it. Adipocere formation in the buccal pad of fat will retain the outline of the cheeks. Unlike mummification, the process of adipocere formation occurs in corpses in environments that are high in moisture. Anaerobic conditions, such as a flooded burial or submersion in water, facilitate adipocere formation. The process primarily involves hydrolysis and hydrogenation of body fats to fatty acids and soaps and adipocere formation. Although reports exist of adipocere formation occurring as early as about three weeks after death, in most cases, it becomes apparent only months after death.

sources:

https://en.wikipedia.org/wiki/Corpse_decomposition#:~:text=The%20five%20stages%20of%20decomposition,decay%20of%20a%20pig%20corpse.

https://australian.museum/learn/science/stages-of-decomposition

https://www.science.org.au/curious/decomposition

https://aboutforensics.co.uk/decomposition

https://www.ncbi.nlm.nih.gov/books/NBK549867

https://www.researchgate.net/figure/Illustration-of-the-five-stages-of-the-decomposition-process-fresh-F-bloat-B-decay_fig1_51850220

Music in the video

Down in a Hole by Alice in Chains

Whiter Shade of Pale by Procol Harum

The End by The Doors

Demons Call by BatchBug

!Memento_mori

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