Types of laboratories according to their functional purpose. Laboratory analysis: types, conduct, goals

Laboratory diagnostics is one of the most important areas of medicine, without which it is impossible to imagine the work of doctors. The data obtained after the examinations allow us to reliably make a diagnosis, as well as assess the general condition of the patient and see the effectiveness of the selected treatment. Analyzes are carried out by specialists - laboratory diagnostic doctors.

Types of analyzes

To clarify the diagnosis, the doctor must have a complete clinical picture. It includes not only the collection of complaints, initial examination and medical history, but also the appointment of laboratory and instrumental types of examinations. The latter include:

1. General clinical tests. This is a huge group that includes blood, urine, and stool tests. Laboratory diagnostics is the process of obtaining data about the patient’s condition within a few minutes. The fastest way to find out what changes are occurring in the body is to do a basic examination. This will be enough to determine the presence of blood loss, inflammation, infection and other possible disorders. After about an hour, the doctor receives data on the patient’s condition.
2. Coagulogram. This is a laboratory diagnosis that analyzes the degree of blood clotting. The usual system of tests includes the assessment of pathological blood clotting. This type of diagnosis is carried out during pregnancy, with varicose veins, before and after surgery. Laboratory diagnostics is a fairly informative method that allows you to monitor treatment with an indirect anticoagulant and more.
3. Biochemistry of blood. This group of studies is carried out using several parameters, including determinations of creatinine, glucose, uric acid, cholesterol and other substances.
4. Tumor markers. To treat cancer, it is important to make a timely diagnosis, determining the type of disease and its stage. One of the examination methods is clinical laboratory diagnostics in the form of tumor markers. Their use makes it possible to determine the early stage of the disease, as well as control treatment.
5. Hormonal examination. These laboratory diagnostic methods make it possible to determine the reproductive capacity of a wide variety of glands, including the adrenal glands, thyroid gland, pancreas, etc.
6. Infectious testing. This group includes tests for a wide variety of infectious diseases, including hepatitis, HIV, herpes, rubella and more. Each examination is of great importance for medicine.

Special types of laboratory tests

This should include all studies that are not general or infectious, but have special techniques for performing them. This:

• Allergy tests. In case of frequent respiratory and infectious pathologies, weakened immunity, or the presence of a chronic disease, immunological tests are performed. If the patient has frequent allergies, then it is necessary to conduct allergy tests. They will allow you to determine what substances a pathological reaction occurs to.
• Toxic. This group includes tests for alcohol, drugs, and toxins.
• Cytology. This laboratory diagnosis allows you to determine the condition of the cells, namely to evaluate their structure, composition, the presence of fluid in the body to determine deviations from the norm, as well as for the purpose of prevention.

Specific tests

Another specific diagnostic method is bacteriological culture. They are carried out to detect infectious agents in urine, smears, and on tissue particles.

Activities of a laboratory specialist

A clinical laboratory doctor performs a variety of tests. Health workers use knowledge of the basics of laboratory work and apply in practice the most modern technologies for studying the obtained material. Also in the laboratories, solutions and reagents are prepared for performing tests and qualitative research of the material.

A clinical laboratory diagnostics doctor must know and be able to conduct various types of analyzes, tests, samples, and evaluate their results.

Benefits of laboratory testing

Each type of diagnosis has many advantages. Among the most informative, it is worth highlighting laboratory examination. It allows you to reliably make a diagnosis, receiving maximum information. Tests can be performed very quickly, which is especially important in emergency cases when it is necessary to accurately determine the cause of the disease.

Conducting laboratory diagnostics has a fairly wide range of studies, allowing for any type of ailment to identify what exactly caused the pathology and what changes it caused in the body. Also, test data helps determine the treatment method.

Conclusion

The importance of laboratory examination methods is difficult to underestimate. They help determine treatment tactics and largely influence its results. Using various testing methods, doctors are able to accurately identify the true cause of the disease and predict the outcome of the disease, as well as determine whether the patient can be cured completely or whether it is possible to achieve stable remission.

Every year, new examination methods are developed, with the help of which the process of assessing the patient’s condition and the quality of treatment is accelerated. Many types of illnesses are identified in a matter of minutes. In laboratory centers, work is constantly being done to improve workplaces, new equipment and tests are being introduced for the work of laboratory technicians. All this speeds up and simplifies the work of professionals, and the accuracy of the results increases.

Laboratory research methods - examination of biological material ( biosubstrates). Biomaterials - blood and its components (plasma, red blood cells), urine, feces, gastric juice, bile, sputum, effusion fluids, tissues of parenchymal organs obtained from biopsy.

Purpose of laboratory research:

• establishing the etiology of the disease (its cause); sometimes this is the only criterion for assessing a clinical situation - for example, infectious diseases;
• prescription of treatment;
• monitoring the effectiveness of treatment over time.

Laboratory tests are ordered and evaluated by a physician. Laboratory staff are responsible for the laboratory stage. In the preanalytical stage, the nurse plays an important role:

• prepares the patient for the study, provides him with laboratory glassware, issues a referral for the study;
• collects biomaterial and ensures proper storage;
• transports the material to the laboratory.

The reliability of the research depends on how well this stage is completed.

Types of laboratories, their purpose

Clinical and diagnostic

Determination of physicochemical properties of biological substrates and microscopy. For example, general analysis (blood, urine, sputum, feces), urine tests according to Zimnitsky and Nechiporenko, feces for occult blood, feces for helminth eggs, general analysis of gastric juice and bile, exudates and transudates, cerebrospinal fluid, etc. To transport biomaterials to the laboratory, clean, dry glassware or special disposable containers are used.

Biochemical

Determination of chemical properties of biological substrates. For example, liver blood tests (total protein, bilirubin, thymol and sublimate tests), blood for rheumatic tests (C-reactive protein, formol test), study of lipid metabolism (beta-lipoproteins, total cholesterol), enzymes (ALAT, ASAT, LDH and etc.), study of carbohydrate metabolism (blood glucose), blood test for iron, electrolyte content, biochemical study of bile and urine, etc.

Bacteriological (clinical microbiology laboratory)

Detection of microbial composition and identification of microflora (blood for sterility, urine for bioculture, feces for intestinal group and dysbacteriosis, swab from the throat and nose if diphtheria and meningococcal infection are suspected, serological blood tests, etc.). To collect the material, you must obtain sterile laboratory glassware. Material should be collected before starting antibiotic therapy.

According to the degree of radiation hazard, work with open radioactive substances is divided into three classes, depending on the activity in the workplace, the radiotoxicity group of the radioactive isotope and the nature of the work performed.

The classification of work carried out with open radioactive substances during conventional chemical operations is given in Table. 13.

TABLE 13. Classification of work carried out with open radioactive substances

To establish the class of work with other types of chemical operations when using isotopes of a given toxicity group (see page 328), the corresponding value given in table follows. 13, multiply by the correction factor, the values ​​of which are indicated below:

Corrective

Nature of the process coefficient

According to the class of work, laboratories must have appropriate equipment, and they are also divided into three classes.

For third-class work, there are no special requirements for the layout of laboratories, but it is better to carry them out in separate rooms. Laboratory equipment must meet the requirements for conventional chemical laboratories. Simple and routine third-class operations can be performed on laboratory benches, and more complex ones can be performed in ordinary fume hoods with appropriate precautions.

Second class work is carried out in separate, specially equipped rooms. Such a laboratory should have a special storage of isotopes, separate rooms for packaging, for chemical work, for measurements, a shower, a dosimetry control point, and a room for receiving and storing food. In laboratories, increased (5-10-fold) air exchange, special cabinets, boxes and protective chambers are installed. Special requirements apply to covering walls, floors, and equipment.

The storage facility for radioactive substances must be located in a separate room and equipped with safes for storing radioactive substances, means for moving heavy protective containers, and a place for preliminary processing of substances with remote equipment.

In safes, radioactive substances are placed in containers.

The laboratory must have protective screens (fixed or collapsible), means of remote work (manual and mechanical manipulators, forceps, etc.).

All second class work is performed in fume hoods or boxes.

A description of laboratories for first-class work is not part of our task, since such work is carried out only during activation analysis, using a nuclear reactor.

Medical laboratories

healthcare institutions or structural units of treatment and preventive or sanitary institutions intended for conducting various medical research. This group does not include research laboratories. One of the main types of L.m. is clinical diagnostic (CDL). The area of ​​the KDL, including utility rooms, must be at least 20 m 2 per 1 employee, the area of ​​the laboratory premises itself is at least 10 m 2 per 1 employee performing tests. The activities of CDLs and their standard procedures are regulated by official documents. The widest range of laboratory tests is carried out in the clinical laboratory of republican, regional, regional, and clinical city hospitals.

The cytological laboratory conducts cytological studies (Cytological examination) of the material obtained from the biopsy. It is part of the CDL or, in the form of a centralized cytology laboratory, part of an oncology dispensary, a large multidisciplinary hospital.

The forensic laboratory is intended mainly to obtain objective data when examining corpses, biological evidence and when examining living persons, to establish the lifetime and duration of injuries, the time of death, etc. It carries out a complex of laboratory tests (morphological, biochemical, immunological, serological), spectral, X-ray studies (see Forensic laboratory tests) .

Pathological laboratory - a subdivision of the pathological department of a medical institution, in which macro- and microscopic examinations of sectional and biopsy material are carried out (see Pathological service) . Main tasks of L.m. - establishing the causes and mechanisms of death of the patient, conducting diagnostic puncture and aspiration biopsies of organs and tissues.

Sanitary and hygienic laboratory is a subdivision of the SES that conducts instrumental and instrumental studies necessary for the implementation of preventive and routine sanitary supervision (Sanitary supervision) . The laboratory conducts instrumental (hardware) environmental studies of industrial, utility and other facilities located in the territory served by the SES. Research is carried out according to the plan of the units of the hygiene department of the SES (occupational hygiene, municipal hygiene, food hygiene, hygiene of children and adolescents, etc.).

Radioisotope laboratory (radioisotope diagnostic laboratory) is a structural unit of a medical and preventive institution (if the institution has a radiological department, it is created as part of it). Organized as part of a regional (territorial, republican), city hospital, diagnostic center, oncology clinic, other treatment and preventive institutions or institutes and ensures diagnostic studies (see Radionuclide diagnostics) , and with appropriate permission from the sanitary and epidemiological service authorities - and with the help of radiopharmaceuticals (Radiopharmaceuticals) . L.m. is equipped with diagnostic, protective and dosimetric monitoring equipment to carry out a range of studies required by this institution. Permission to work (to work with sources of ionizing radiation) is given by the SES.

Organizational and methodological management is carried out by the main freelance specialists in the laboratory service of local health authorities.

A special role belongs to L.m. republican, regional, regional hospitals and SES, which must provide the maximum level of laboratory tests; they are organizational, methodological, scientific, technical and educational centers of the corresponding administrative territories. Their responsibilities include studying and analyzing the work of laboratories in the region, disseminating best practices, improving the qualifications of doctors and laboratory technicians, providing advisory assistance, introducing unified methods, monitoring the quality of research, etc.

The main performance indicators of L.m. are the average daily workload of an employee, determined by calculation units, as well as the number of tests per 1 patient in a hospital, per 100 outpatient visits, per 1 doctor conducting an appointment, per 1000 population. Due to the presence in L.m. electrical equipment, equipment, chemical reagents and toxic substances, infected material, etc. Much attention is paid to safety precautions.

In military field conditions L.m. organized as part of military field medical institutions or independently. They are intended for laboratory diagnostics of combat pathology, identification and examination of objects contaminated as a result of the use of weapons of mass destruction. Such L.m. perform clinical-hematological, sanitary-hygienic, bacteriological, pathoanatomical, forensic and other studies. works by L.m. depends on the combat situation, the intensity of the flow of wounded and sick people, and the nature of the combat pathology. L. m. are equipped with complete equipment.

1. Small medical encyclopedia. - M.: Medical encyclopedia. 1991-96 2. First aid. - M.: Great Russian Encyclopedia. 1994 3. Encyclopedic Dictionary of Medical Terms. - M.: Soviet Encyclopedia. - 1982-1984.

See what “Medical laboratories” are in other dictionaries:

Medical research institutes in the USSR, institutions conducting research in the field of medicine. The development of the research institute network is associated with the development and establishment of the state socialist healthcare system. Medical research institutes can... ...

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I Medical institutes are higher educational institutions that train doctors in the following specialties: general medicine, pediatrics, sanitation, dentistry; pharmacists; Faculty of Medicine and Biology at the 2nd Moscow M.I. trains biophysicists and... Great Soviet Encyclopedia

Laboratory management- (laboratory management): a person or persons who manage the activities of the laboratory, headed by the head of the laboratory... Source: Medical laboratories. Particular requirements for quality and competence. GOST R ISO 15189 2009 (approved by Order... ... Official terminology

- (Greek diagnostikos capable of recognizing) a set of physicochemical, biochemical and biological diagnostic methods that examine deviations in the composition and changes in the properties of the patient’s tissues and biological fluids, as well as identifying... ... Medical encyclopedia

Medical laboratory- Medical laboratory (medical laboratory, clinical laboratory): a laboratory that conducts biological, microbiological, immunological, chemical, immunohematological, hematological, biophysical, cytological,… … Official terminology

A set of technical devices (instruments, apparatus, devices) that make it possible to conduct medical laboratory research. The main purpose of M.l.t. in medical laboratories (medical laboratories) research of chemicals... ... Medical encyclopedia

I Polyclinic is a treatment and preventive institution designed to provide out-of-hospital medical care to the population and carry out a set of preventive measures aimed at reducing morbidity. The country operates... Medical encyclopedia

Laboratory capabilities- Laboratory capabilities: material, territorial and information resources, personnel, their skills and knowledge provided for the proposed research. Note A laboratory capacity assessment may include... Official terminology

- (Leipzig) the second largest, first important city of the kingdom of Saxony, in its northwestern part, 8 km from the Prussian border, 118 m above sea level, in a fertile plain, irrigated by pp. Place, Elster and Parta. Comprises… …

- (Leipzig) is the second largest, the first in importance mountains. cor. Saxony in the north zap. part of it, 8 km from the Prussian border, 118 m above sea level, in a fertile plain irrigated by pp. Place, Elster and Parta. Consists of an inner city, five... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Books

• Medical laboratory technologies. Manual for clinical laboratory diagnostics. Volume 1, Anatoly Ivanovich Karpishchenko, N. P. Mikhaleva, G. I. Maslova. The basics of laboratory analytics, quality control of research are outlined, the equipment and technical equipment of the laboratory are presented. Unified research methods are covered...

All microbiological, biochemical and molecular biological studies of microorganisms are carried out in special laboratories, the structure and equipment of which depend on the objects of study (bacteria, viruses, fungi, protozoa), as well as on their target orientation (scientific research, disease diagnosis) . The study of the immune response and serodiagnosis of human and animal diseases is carried out in immunological and serological (serum - blood serum) laboratories.

Bacteriological, virological, mycological and serological (immunological) laboratories are part of sanitary-epidemiological stations (SES), diagnostic centers and large hospitals. In SES laboratories, they perform bacteriological, virological and serological analyzes of materials obtained from patients and persons in contact with them, examine bacteria carriers and conduct sanitary and microbiological studies of water, air, soil, food products, etc.

In bacteriological and serological laboratories of hospitals and diagnostic centers, they conduct research to diagnose intestinal, purulent, respiratory and other infectious diseases, and carry out microbiological control over sterilization and disinfection.

Diagnosis of especially dangerous infections (plague, tularemia, anthrax, etc.) is carried out in special sensitive laboratories, the organization and procedure of which are strictly regulated.

Virology laboratories diagnose diseases caused by viruses (influenza, hepatitis, polio, etc.), some bacteria - chlamydia(ornithosis, etc.) and rickettsia(typhus, Q fever, etc.). When organizing and equipping virology laboratories, the specifics of working with viruses, cell cultures and chicken embryos, which require the strictest asepsis, are taken into account.

In mycological laboratories, they diagnose diseases caused by pathogenic fungi and pathogens of mycoses.

Laboratories are usually located in several rooms, the area of ​​which is determined by the volume of work and the intended purpose.

Each laboratory provides:

a) boxes for working with individual groups of pathogens;

b) premises for serological research;

c) premises for washing and sterilizing dishes, preparing
lenition of nutrient media;

d) a vivarium with boxes for healthy and experimental animals;
nykh;

e) registry for receiving and issuing tests.

Along with these premises, virology laboratories have boxes for special processing of research material and work with cell cultures.

Equipment for microbiological laboratories

Laboratories are equipped with a number of mandatory instruments and apparatus.

1. Instruments for microscopy: biological immersion microscope with additional devices (oscillator, phase-contrast device, dark-field condenser, etc.), fluorescence microscope.

2. Thermostats and refrigerators.

3. Equipment for preparing nutrient media, solutions, etc.: apparatus for producing distilled water (distiller), technical and analytical balances, pH meters, filtration equipment, water baths, centrifuges.

4. A set of tools for manipulating microbes: bacteriological loops, spatulas, needles, tweezers, etc.

5. Laboratory glassware: test tubes, flasks, Petri dishes, mattresses, vials, ampoules, Pasteur and graduated pipettes, etc., apparatus for making cotton-gauze plugs.

Large diagnostic complexes have automatic analyzers and a computerized system for assessing the information received.

The laboratory has a designated area for staining microscopic preparations, where there are solutions of special dyes, alcohol, acids, filter paper, etc. Each workplace is equipped with a gas burner or alcohol lamp and a container with a disinfectant solution. For daily work, the laboratory must have the necessary nutrient media, chemical reagents, diagnostic drugs and other materials.

Large laboratories have thermostatic rooms for mass cultivation of microorganisms and serological reactions. The following equipment is used for growing, storing cultures, sterilizing laboratory glassware and other purposes.

1. Thermostat. A device in which a constant temperature is maintained. The optimal temperature for the reproduction of most pathogenic microorganisms is 37 "C. Thermostats are air and water.

2. Microanaerostat. Apparatus for growing microorganisms under anaerobic conditions.

3. C0 2 -incubator. An apparatus for creating a constant temperature and atmosphere of a certain gas composition. Designed for the cultivation of microorganisms that are demanding on the gas composition of the atmosphere.

4. Refrigerators. Used in microbiological laboratories for storing cultures of microorganisms, nutrient media, blood, vaccines, serums and other biologically active preparations at a temperature of about 4 °C. To store drugs at temperatures below 0 °C, low-temperature refrigerators are used, in which the temperature is maintained at -20 °C or -75 °C.

5. Centrifuges. Used for sedimentation of microorganisms, erythrocytes and other cells, for separation of heterogeneous liquids (emulsions, suspensions). Laboratories use centrifuges with different operating modes.

6. Drying and sterilization cabinet(Pasteur oven). Designed for dry-air sterilization of laboratory glassware and other heat-resistant materials.

7. Steam sterilizer (autoclave). Designed for sterilization with superheated water steam (under pressure). In microbiological laboratories, autoclaves of different models are used (vertical, horizontal, stationary, portable).

BACTERIOLOGICAL, VIRUSOLOGICAL, MYCOLOGICAL, IMMUNOLOGICAL LABORATORIES AND THEIR EQUIPMENT. DEVICE OF MODERN MICROSCOPE. METHODS OF MICROSCOPY. METHODS FOR STUDYING THE MORPHOLOGY OF MICROORGANISMS

Program

1. Rules of work and organization of microbiological (bacteriological, virological, mycological) laboratories.

2. Basic instruments and equipment of a microbiological laboratory.

3. Microscopes and microscopic equipment. Rules for working with an immersion microscope (objectives).

Demonstration

1. Design and use of basic instruments and equipment used in microbiological laboratories: thermostat, centrifuges, autoclave, drying cabinet, instruments and utensils.

2. Design of a biological microscope. Various microscopy methods: dark-field, phase-contrast, fluorescent, electron.

3. Preparations of microbes (yeast and bacteria) using various microscopy methods.

Assignment for students

1. Microscope and sketch preparations of yeast-like fungi of the genus Candida using different types of microscopy.

Guidelines

Rules for working in microbiological laboratories.

Work in the microbiological laboratory of a medical institution is carried out with causative agents of infectious diseases - pathogenic microorganisms.

Therefore, to protect against infection, personnel must strictly adhere to the internal regulations:

1. All employees must work in medical gowns, caps and removable shoes. Entry into the laboratory without a gown is strictly prohibited. If necessary, workers put a gauze mask on their face. Work with especially dangerous microbes is regulated by special instructions and is carried out in sensitive laboratories.

2. Smoking and eating are prohibited in the laboratory.

3. The workplace must be kept in exemplary order. Personal belongings of employees should be stored in a specially designated place.

4. If infected material accidentally gets on the table, floor or other surfaces, this place must be thoroughly treated with a disinfectant solution.

5. Storage, observation of microbial cultures and their destruction must be carried out in accordance with special instructions. Cultures of pathogenic microbes are registered in a special journal.

6. Upon completion of work, hands should be washed thoroughly and, if necessary, treated with a disinfectant solution.

Microscopes and microscopy methods

Rice. 1.1. Microscopes.

a — general view of the Biolam microscope; b — MBR-1 microscope: 1 — microscope base; 2 - object table; 3 — screws for moving the object stage; 4 — terminals that press the drug; 5 - condenser; 6 — condenser bracket; 7 - screw securing the condenser in the sleeve; 8 — handle for moving the condenser; 9 — handle of the iris diaphragm of the condenser; 10 - mirror; 11 — tube holder; 12 — macrometric screw handle; 13 — micrometer screw handle; 14 — lens revolver; 15 — lenses; 16 — inclined tube; 17 — screw for fastening the tube bead; 18 - eyepiece.

For microbiological studies, several types of microscopes (biological, fluorescent, electronic) and special microscopy methods (phase contrast, dark field) are used.

In microbiological practice, microscopes of domestic brands are used: MBR-1, MBI-2, MBI-3, MBI-6, "Bio-lam" R-1, etc. (Fig. 1.1). They are designed to study the shape, structure, size and other characteristics of various microbes, the size of which is at least 0.2-0.3 microns.

Immersion microscopy

Used to increase the resolution of the method light microscopy. The resolution of a light-optical microscopy system is determined by the wavelength of visible light and the numerical aperture of the system. The numerical aperture measures the angle of maximum cone of light entering the lens and depends on the optical properties (refractive power) of the medium between the object and the objective lens. Immersing the lens in a medium (mineral oil, water) that has a high refractive index, close to that of glass, prevents light from scattering from the object.

Rice. 1.2. Path of rays in an immersion system, n is the refractive index.

Rice. 1.3. Ray path in dark-field condensers, a - paraboloid-condenser; b — cardioid condenser; 1 - lens; 2 - immersion oil; 3 - drug; 4 - mirror surface; 5 - diaphragm.

In this way, an increase in the numerical aperture and, accordingly, resolution is achieved. For immersion microscopy, special immersion objectives equipped with a mark are used (MI - oil immersion, VI - water immersion). The maximum resolution of an immersion microscope does not exceed 0.2 microns. The path of rays in the immersion system is shown in Fig. 1.2.

The overall magnification of a microscope is determined by the product of the objective magnification and the eyepiece magnification. For example, the magnification of a microscope with an immersion objective of 90 and an eyepiece of 10 is: 90 x 10 = 900.

Microscopy in transmitted light (bright-field microscopy) used to study colored objects in fixed preparations.

Dark-field microscopy. It is used for intravital study of microbes in native unstained preparations. Dark field microscopy is based on the phenomenon of light diffraction under lateral illumination of particles suspended in a liquid ( Tyndall effect). The effect is achieved using a paraboloid or cardioid condenser, which replaces a conventional condenser in a biological microscope (Fig. 1.3). With this lighting method, only rays reflected from the surface of the object enter the lens. As a result, brightly luminous particles are visible against a dark background (unlit field of view). The drug in this case has the form shown in Fig. 1.4, b (on the inset).

Phase contrast microscopy. Designed for the study of native drugs. A phase-contrast device makes it possible to see transparent objects through a microscope. Light passes through different biological structures at different speeds, which depend on the optical density of the object. As a result, a change in the phase of the light wave occurs that is not perceived by the eye. A phase device, including a special condenser and lens, ensures the conversion of changes in the phase of a light wave into visible changes in amplitude. In this way, an increase in the difference in the optical density of objects is achieved. They acquire high contrast, which can be positive or negative. Positive phase contrast is a dark image of an object in a bright field of view, negative phase contrast is a light image of an object on a dark background (see Fig. 1.4; inset).

For phase-contrast microscopy, a conventional microscope and an additional phase-contrast device KF-1 or KF-4 (Fig. 1.5), as well as special illuminators, are used.

Luminescent (or fluorescent) microscopy. Based on the phenomenon of photoluminescence.

Luminescence- glow of substances that occurs under the influence of external radiation: light, ultraviolet, ionizing, etc. Photoluminescence - luminescence of an object under the influence of light. If you illuminate a luminescent object with blue light, it emits rays of red, orange, yellow or green. The result is a color image of the object.

Rice. 1.5. Phase contrast device, a - phase lenses; b - auxiliary microscope; c - phase capacitor.

The wavelength of the emitted light (luminescence color) depends on the physicochemical structure of the luminescent substance.

Primary luminescence of biological objects (own, or bioluminescence) is observed without preliminary staining due to the presence of its own luminescent substances, secondary (induced) - occurs as a result of staining preparations with special luminescent dyes - fluorochromes(acridine orange, auromin, coryphosphine, etc.). Luminescent microscopy has a number of advantages over conventional methods: the ability to examine living microbes and detect them in small concentrations in the material under study due to the high degree of contrast.

In laboratory practice, fluorescent microscopy is widely used to identify and study many microbes.

Electron microscopy. Allows you to observe objects whose dimensions lie beyond the resolution of a light microscope (0.2 microns). An electron microscope is used to study viruses, the fine structure of various microorganisms, macromolecular structures and other sub-microscopic objects. Light rays in such microscopes are replaced by a stream of electrons, which at certain accelerations has a wavelength of about 0.005 nm, i.e. almost 100,000 times shorter than the wavelength of visible light. The high resolution of the electron microscope, reaching 0.1-0.2 nm, allows a total useful magnification of up to 1,000,000.

Along with translucent type devices, they use scanning electron microscopes, providing a relief image of the surface of the object. The resolution of these devices is significantly lower than that of transmission electron microscopes.

Rules for working with a microscope

Working with any light microscope includes setting the correct illumination for the field of view and the specimen and microscopying it with various lenses. Lighting can be natural (daylight) or artificial, for which special light sources are used - illuminators of different brands.

When microscopying specimens with an immersion lens, you should strictly adhere to a certain order:

1) apply a drop of immersion oil to the smear prepared on a glass slide and stained and place it on the stage, securing it with clamps;

2) turn the revolver to the immersion lens mark 90x or 10Ох;

3) carefully lower the microscope tube until the lens is immersed in a drop of oil;

4) set the approximate focus using a macrometric screw;

5) carry out final focusing of the preparation with a micrometer screw, rotating it within only one turn. Do not allow the lens to come into contact with the
paratomy, as this may lead to breakage of the cover glass or the front lens of the objective lens (free distance of the immersion objective 0.1-1 mm).

After finishing the microscope, it is necessary remove oil from the immersion lens and transfer the revolver to the small 8x lens.

For dark-field and phase-contrast microscopy, native preparations are used ("crushed" drop, etc., see topic 2.1); microscope with a 40x objective or a special immersion objective with an iris diaphragm, which allows you to adjust the numerical aperture from 1.25 to 0.85. The thickness of glass slides should not exceed 1 - 1.5 mm, cover glasses - 0.15-0.2 mm.