Imbibition

IMBIBITION, imbibitio (from Latin imbibere - to absorb), saturation. The term Imbibition is used to denote the saturation of some denser material by one or another liquid medium; however, in a physical sense, the mechanism of this saturation can be different. In some cases, one can speak of molecular imbibition, assuming that the basis of the saturation mechanism is molecular adsorption of the liquid by the denser material; in other cases, the penetration of liquid into tissue occurs according to the laws of capillarity (capillary imbibition); in third cases, one can think of the swelling of colloids as the basis of imbibition. Often, a combination of the above factors can also be assumed. In particular, imbibition can include the saturation of tissues by some artificial coloring substances (imbibition by dye); further, when saturating various coverings or other materials (e.g., non-necrotized Peyer's patches in typhus) with bile, one speaks of imbibition by bile; the saturation of tissues with transudate in edema is also imbibition. Finally, in pathological anatomy and forensic medicine, postmortem imbibition has great significance, i.e., the saturation of the tissues of a corpse by decomposing blood. The essence of this phenomenon is that during postmortem decomposition, blood hemoglobin is leached from erythrocytes and is found dissolved in plasma; in connection with this, the inner surface of vessels and cavities of the heart containing blood and blood clots undergoes imbibition by hemoglobin dissolved in plasma, which is expressed in the coloring of these parts in a dirty-red color. Subsequently, due to the penetration of plasma colored with hemoglobin through the vessel walls into the surrounding tissue, imbibition of soft tissues by plasma with hemoglobin occurs along the course of the vessels. This type of phenomenon is observed first of all and is most pronounced in those places where there are postmortem hypostases; with the corpse lying on its back, such a place is the skin of the posterior surface of the trunk and extremities, on which as a result of imbibition along the course of veins distended with blood, a peculiar network of brownish-red stripes appears. Near the jugular veins (bulbus ven. jugul.), limited saturation of loose connective tissue resembling a bruise is also noticeable. From the internal organs, the posterior parts of the lungs, the underlying loops of the intestine, the posterior wall of the stomach, the meninges and brain substance in their posterior parts undergo postmortem imbibition. In particular, in the lungs with sharply expressed imbibition, the posterior parts become almost black and airless, and on the posterior wall of the stomach, coffee-colored stripes appear along the course of veins distended with blood due to the change in hemoglobin under the influence of the acidic contents of the stomach. Postmortem imbibition, belonging to the group of postmortem changes, usually begins to appear on the corpse 12-15 hours after death; however, it reaches its full development, expressed in the appearance of the above-mentioned network on the skin of the posterior parts of the corpse and sharp changes in the posterior parts of the lungs and other internal organs, only after 3-4 days. On the other hand, however, in corpses of persons who died from septic processes, especially when the corpse is kept in a warm room, very intense manifestations of postmortem imbibition occur already after a few hours. From a forensic-medical point of view, the phenomena of postmortem imbibition have important significance because in some cases they help judge the time that has passed since the moment of death. In addition, familiarity with the changes depending on imbibition is necessary for the forensic expert in view of the fact that such changes sometimes can simulate antemortem hemorrhages from injuries, and in the lungs - pneumonia.