Defatting

DEFATTING in microscopic technique is a necessary procedure for preparing almost every histological stained specimen. The purpose of defatting is to prepare the tissue for more elective absorption of stains and to make the preparation durable during storage. On the other hand, defatting represents an important factor in dehydration. Defatting is especially necessary in cases of embedding the specimen in celloidin or paraffin, as the presence of fat interferes with the impregnation of the piece with these substances. Defatting is not applied only in cases where fat itself is the subject of research (staining with Sudan III, scarlet red, etc., research on double refraction, etc.). Defatting also interferes with the application of certain reactions, for example, for oxidase. When embedding in celloidin, defatting is achieved in alcohol, a mixture of absolute alcohol with ether, and in pure absolute ether (see Histological technique). For paraffin embedding, besides alcohols, powerful defatting substances are xylene, chloroform. When fixing pieces in mixtures containing osmium, which stains fat black and makes it less soluble, absolute alcohol and chloroform no longer extract fat. Frozen sections for defatting are transferred from the knife into water, and then placed in 90-95% alcohol for not less than 15-20 minutes. Some very fat-rich sections can be recommended to be defatted with chloroform, before and after which the sections are passed through absolute alcohol. DISFIGUREMENT in forensic-medical terms, is a significant change under the influence of various harmful factors (mechanical, chemical, etc.) in the external appearance of the most noticeable parts of the human body, which thereby acquire an abnormal, ugly appearance. For damage to be evaluated as disfigurement, it must be obvious; therefore, defects that can be easily concealed by clothing do not fall into this category. Disfigurement is a very conditional and relative concept, as one has to evaluate the consequences of damage not in terms of their significance for the health and life of the victims, but exclusively from an aesthetic point of view. Examples of obvious disfigurement can be the loss of an eye, nose, extensive scars on the face after burns from hot liquids, from the action of caustic substances; the same significance has severe curvature of the body (from burns), clearly noticeable lameness due to damage to the lower extremities. When determining the degree of disfigurement, one should take into account the sex, age of the victims, their appearance before the damage. Thus, the same defects on the face of a man and a woman produce different impressions. Disfigurement of the chest and hands is more significant for girls and young women than for men. Scars on the face of a young woman produce a different impression than on the face of an old woman or a subject who was already previously disfigured. Generally speaking, in view of the special importance for a person of the integrity of the face, extensive skin scars on it can be considered as obvious and indelible disfigurement. It also deserves attention that damage is often inflicted with the intention of causing disfigurement. Besides the loss of the nose, obvious disfigurement is also caused by significant changes in its shape, for example, depression of the bridge due to crushing of the nasal bones. From the side of the eyes, disfigurement can be caused not only by the absence of the eyeball, but also by other changes, such as scars of the cornea, eversion of the eyelids, their drooping, adhesion of the eyelids to the eyeball, etc. The loss of the auricle due to its fairly frequent biting off in other places (Innsbruck) during a fight is disfigurement, but not always obvious, as the ear can be covered by hair, and in forensic-medical practice, cases have been observed where during a judicial investigation of a subject who had lost one auricle in a fight, the absence of the other was only accidentally discovered, while none of those present suspected this. - Damage to the lips and teeth from blows with blunt instruments also causes disfigurement. However, the absence of teeth can only be recognized as obvious, sharply expressed disfigurement in rare cases. Firstly, the loss of many teeth is rare and, moreover, it is relatively easily compensated by a prosthesis; secondly, the absence of teeth for reasons other than trauma (caries) is observed so often that this type of disfigurement can hardly be considered sharply expressed. - The question of whether there is obvious disfigurement in a specific case is subject to judicial evaluation, as medical knowledge is not required to determine aesthetic concepts. The doctor has a different part of the task: to determine whether this disfigurement is indeed indelible. For example, scars on the face can decrease and fade after some time, or conversely, remain unchanged and even increase (keloid). Indelible disfigurement of the face is classified according to our legislation as serious bodily injury (Article 142 of the Criminal Code of the RSFSR 1929).