A study of sperm

Semen is a mixture of secret male sex glands - the testes and epididymis, seminal vesicles, the prostate gland and sperm ways. In cases of rape, sodomy, indecent assault sperm can be found on the body and clothing of the victims, surrounding objects, as well as on the body and clothing of the offender.
Of great importance to establish the fact of sexual intercourse is given to the detection of sperm in the vagina of the Complainant, and in the Commission of a sexual act in a perverted form, and when the sodomy - the content of the rectum of the victim or the victim. Therefore, swabs taken from the vagina serve as an important material evidence. They should be taken as soon as possible, because the sperm, as a rule, remains not for long. For this purpose vagina impose sterile gauze pad, and then the contents of the swab is transferred onto glass slides that and then investigated.
As a rule, if the discharge from the male puts out about a 4-5 ml of semen, rarely - very small (0.5 to 0.2 ml) (oligospermia). Can meet pathological conditions of the sperm: necrosphere (no sperm motility) and azoospermia (sperm are absent) .
Dried semen stains are usually denser to the touch than the surrounding tissue. Their color depending on the material of the object-media can be from light to grayish-yellow or even brown. When viewed in ultraviolet rays traces of sperm glow bluish-white. If you find traces similar to the sperm, the investigator comes as with traces of blood: items to remove traces, traces describe, take measures to preserve them is Packed and sent to study in the forensic laboratory.
The presence of sperm in spots is done using a series of preliminary and evidence-based research methods. Preliminary research methods research in ultra-violet beams (spot semen glow bluish-white color), microcrystalline reaction, the reaction with potato juice, response to acid phosphatase is not sufficiently specific and can only be suspected of seed origin spots.
The main evidence-based method is morphological, based on the finding in the study spot sperm. From a fabric, which is suspicious spot, cut the string or a piece, razvorachivaet and paint the erythrosine, Magenta. The drug is examined under a microscope. Detection of at least one sperm shows that the stain left seminal fluid. The negative results of morphological study of sperm in smears can sometimes depend on the partial destruction of their microflora of the vagina. In the study of semen stains such a result can be explained by the destruction of sperm under the influence of various factors of external environment - chemical, thermal, etc. or azoospermia. When Avialinii sperm in the studied spot morphological method use other methods - enzyme detection method-specific seminal plasma enzyme lactate dehydrogenase (LDH), the method of identification of special proteins - choline and spermine, characteristic only for the sperm. Enzymatic method allows to reveal semen stains only minor ago. At present, methods, allowing to identify the spot sperm separate protein fraction, is characteristic only of the sperm. In expert practice such methods are not yet being implemented. There are also methods to determine the origin of the spots from sperm based detection inherent microelements (emission-spectral studies).
Proving seed origin spot, move on to the definition of group affiliation sperm system AB0(N). Antigens of this system in the sperm are found in large amounts expressed much. Definition of group affiliation semen stain is required for the decision of a question on possibility of its origin from a certain specific person. Such a study is made taking into account the category of videotest - establish which of the two main categories on the content of the antigens in the discharge is passing on to male - to highlighters or evidentially.
Category videotest usually installed in the saliva, which are defined antigens system AB0(N). To do this, the subject is asked to rinse the mouth with water, and then collect saliva in a test tube - 3-5 ml Saliva centrifuged, the liquid part poured on gauze, which is then dried and sent as a model in the forensic laboratory. In this sample, the expert determines antigens system AB0(N). Should be noted that the severity of the group antigens of one and the same person in different secretions may be unequal, and therefore available to the expert in such cases, you must also submit, in addition to samples of saliva, sperm samples.
If the blood of the accused, which needletailed, coincides with the group of sperm in the spot, a conclusion is made about the origin of sperm from another man. When matching blood group men-selector with a group of sperm in the spot at the decision of a question on opportunities of origin semen stain from this man must take into account the force of expressiveness of the group antigens. If the force of expressiveness of the group antigens system AB0(H) in the sample of sperm accused significantly inferior to that of the studied spot sperm, the conclusion about the origin of sperm from another person. In a reverse correlation to the severity of the group antigens (high activity in the sample of sperm and low traces of semen on material evidence cannot exclude the possibility of origin of semen from the accused, as the weakening of the power of manifestation group antigens may be a consequence of the impact of various external factors.
Often traces of sperm on the material evidences are mixed with other secretions of the body or the blood of a man. In such cases, the establishment of group affiliation sperm is very difficult, because in all these secretions and blood can contain its own group antigens system AB0(N).
For purposes of differentiation antigens of different origin proposed methods based on the thermal fixation group antigens of blood in mixed spots and subsequent detection of antigens, peculiar only to the sperm. To differentiate the group antigens of sperm and blood mixed spots proposed and other methods - selective extraction of such spots certain chemicals, which enable to output the studied extract any seed or blood antigens system AB0(N), immunofluorescence method and others In recent years, the possibility of revealing the traces of sperm hereditary groups phosphoglucomutase and phosphogluconate-dehydrogenase and some other enzymes.
When establishing the possibility of origin of semen on material evidence from a particular person in the forensic laboratory also sent samples of liquid blood of the victim and the suspect to determine their group, their saliva samples to establish the category of videotest.