Embalming temporarily preserves human remains and slows decomposition through the arterial injection of specialized chemical solutions into the circulatory system. The most common immediate physical change is the distinct firmness or rigidity of the tissues. This hardening is an intended consequence of the chemical reaction designed to stabilize the body for sanitation and viewing.
The Key Chemical Agent
The chemical agent primarily responsible for tissue preservation and hardening is formaldehyde, often used in a water-based solution called formalin. This substance forms the foundation of most modern embalming fluids, though they may also contain other chemicals like glutaraldehyde. The concentration of formaldehyde in the fluid, known as the index, typically ranges from 18% to 37%. This preservative is injected into the arteries, displacing the blood and permeating the surrounding tissues and cells. Its effectiveness comes from its ability to chemically react with the cellular components of the body, stopping the internal processes of decay.
How Formaldehyde Causes Tissue Hardening
The hardening effect, known scientifically as fixation, occurs through a chemical process called protein cross-linking. Body tissues, particularly muscle and connective tissue, are composed of proteins, which are flexible chains of amino acids. Formaldehyde molecules react strongly with the nitrogen-containing amino groups found in these protein chains.
This reaction forms new, stable chemical bonds, specifically methylene bridges, that link adjacent protein molecules together. These cross-links create a rigid, three-dimensional mesh or scaffolding within the tissue. This structural change locks the proteins into a fixed state, preventing them from being broken down by the body’s own enzymes or by bacteria. The resulting fixed tissue is physically toughened, giving the embalmed body its characteristic firmness.
Controlling the Degree of Firmness
The degree of firmness achieved is a highly controlled aspect of the embalming process managed by the practitioner. Embalmers carefully select the concentration, or strength, of the arterial fluid, which determines the final texture of the body. A higher concentration of formaldehyde leads to more extensive protein cross-linking and greater tissue firmness. The total volume and rate of injection are also adjusted to control the outcome. For example, a stronger solution is used for cases requiring long-term preservation, while a less concentrated solution is used if the goal is a softer, more natural presentation for a short viewing period.
The Broader Goals of Embalming
While tissue hardening is the most apparent result, it supports the broader objectives of the embalming procedure. A primary goal is sanitation, as the chemicals kill pathogenic microorganisms, protecting public health. The fixation of proteins eliminates the food source for putrefactive bacteria, which are the main drivers of decomposition. Another objective is temporary presentation, which involves restoring a natural appearance for viewing services. The procedure delays decompositional changes like discoloration and swelling, and the resulting firmness helps the body maintain its form and features.