Microscope.

In this article I will tell you 3 ways to prepare preparations for a microscope. These methods are the simplest.

At the beginning of the article - the so-called dictionary, or rather explanations of what this or that object is.

For the manufacture of micropreparations, a special tool, dyes, as well as a certain accuracy and skill are required. Strict observance of all necessary conditions is very important - otherwise the micropreparation may be unsuitable for research.

There are ready-made kits for research on sale (which is convenient for home and school) - for example, 25 drugs, or 38 slides from Leeuwenhoek. As well as minerals and other sets.

explanations

Fixed drug- in microbiology, fixed preparations are often prepared, so you should know what they are. These preparations are examined under a microscope in a stained form. The word "fixation" means such processing of a living object (which you are going to consider), which makes it possible to quickly interrupt the life processes in a particular object (I will explain more simply - to kill), while maintaining a fine structure. As a result of fixation, the cells are firmly attached to the glass and stain better. Fixation is necessary in case of work with pathogenic microorganisms (for self-safety purposes).

Suspension- a mixture of any substances, where the solid substance is distributed in the form of tiny particles in a liquid substance in a non-settled state.

biological loop- a thin metal stick, at the end - a thin metal loop. It is used to capture a small amount of a particular suspension of microorganisms.

Petrolatum- ointment-like liquid, odorless and tasteless. The mixture consists of mineral oil and solid paraffins (wax-like mixture).

Sealing- ensuring perfect impermeability for various gases and liquids of surfaces and joints of parts.

agar agar- in microbiology, it is used for the manufacture of solid and semi-liquid nutrient media, that is, agar media.

Carnoy's fluid- liquid for fixing.

Burner- a device having an injector, which is installed in a metal tube with holes for atmospheric air to enter this tube, which is fixed on a stand with a side inlet for supplying gas to the tube, while the holes are made on the side surface of the tube, on which to change the air supply to burner, a movable damper can be installed that changes the flow area of ​​these holes.

Nikiforov's mixture- a mixture of equal volumes of ethyl alcohol and anhydrous sulfuric ether, used to fix blood smears, smears-prints of organs and any tissues.

Preparation of the drug "crushed drop"

Preparation of the drug "hanging drop"

Hanging drop.

1. Gently place one drop of microorganism suspension (prepared) using a biological loop on a clean coverslip.
2. Invert the cover slip containing the suspension drop so that the drop hangs freely.
3. Place an inverted cover slip with a drop over the well of a special coverslip with a depression in the center.
4. The drop should not touch the edges of the glass and the recess (hole), it should hang freely on the coverslip.
5. The edges of the recess of a special cover glass are preliminarily lubricated with Vaseline to seal the chamber.
6. Enjoy observing bacteria in a micropreparation!

Preparation of the drug "imprint"

From an agar medium on which some microorganisms grow in an absolute continuous lawn or in the form of individual colonies, carefully cut out a not very large cube with a scalpel.

Transfer it to a glass slide so that the surface of the microorganism cube is facing up.

Then, apply an ordinary coverslip (absolutely clean) to the lawn of microorganisms or to the colony, gently and not strongly, but lightly, press on it with a biological loop or tweezers and immediately remove it, trying not to move it to the side.

The resulting preparation (a cover slip with an imprint) is placed with the imprint down in a drop of ordinary water on a clean glass slide. An imprint can also be obtained on a glass slide by touching the surface of the colony with the glass slide.

1. The drug is ready!
2. Attention! Living cell preparations are examined using a "dry systems" microscope. After microscopy, such preparations must be kept in a disinfectant solution (disinfectant) before washing.

Preparation of the "imprint" preparation, another method

Preparation of the "fixed smear" preparation

In order to prepare this preparation, one drop of water is required on a defatted glass slide.

Introduce the material you are studying with a biological loop into it and distribute it so as to obtain a thin and uniform smear with a diameter of about 1-1.5 centimeters (only with such a distribution of the material in the smear can you see isolated bacterial cells).

If the test material is contained in a liquid medium, then it is directly applied to a glass slide with a loop and a smear is prepared. The smears are dried in air or in a stream of warm air over a burner flame.


To fix the smear, the glass slide (namely, with the smear up) is very carefully and slowly passed 3 times (within 3 seconds) through the burner flame. The microorganisms in the smear die during fixation, tightly attaching to the surface of the glass slide, and they are not washed off during further processing of the preparation.

1. Ready!

Attention! Longer heating can cause deformation of cell structures. Blood smears, smears-prints of organs and any tissues and (in some cases, smears from cultures) are fixed by immersion for 5-20 minutes in methyl blue or ethyl alcohol, Nikiforov's mixture, also sublimate alcohol or other fixing liquids.

Examples of microscope slides

Botany and zoology:

onion peel
Grain of rye
root cap
linden branch
Anther
Ovary
Camellia
Geranium leaf epidermis
bee limb
bee wing
Cyclops
Volvox
Euglena
Infusoria shoe
Earthworm (cross section)
mosquito mouthparts
Ascaris
Daphnia

Biology and Physiology:

Drosophila mutation (wingless form)
Drosophila mutation (black body)
Drosophila "norm"
animal cell
plant cell
Mold mukor
Cleavage of the egg
Mitosis in an onion root
striated muscles
mammalian spermatozoa
Nerve (cross section)
Loose connective tissue
mammalian egg
Nerve cells
hyaline cartilage
Smooth muscles
Bone
frog blood
human blood
Single layer epithelium

To prepare temporary micropreparations, it is necessary to have a set of slides and coverslips, dissecting needles, razors, scalpels, glass sticks for water, tweezers, filter paper, and some reagents.

The glass slide and coverslip are washed with water and wiped dry with a soft cloth. A thin section of a plant object is placed in a drop of water on a glass slide and covered with a coverslip. If the liquid on the preparation protrudes beyond the edges of the coverslip, then the excess is removed with strips of filter paper. If the water does not cover the entire area under the cover slip, another drop is applied with a pipette near the edge of the cover slip, which itself is drawn under the glass.

If it is necessary to introduce any coloring reagent, the water from under the coverslip is sucked off with filter paper, and a drop of the reagent is applied from the opposite side to the edge of the coverslip.

Coloring reagents can be the following substances:

1) iodine dissolved in potassium iodide (for staining starch grains in cells);

2) chlorine-zinc-iodine (for staining cellulose cell membranes);

3) phloroglucinol and hydrochloric acid (for staining lignified shells);

4) fuchsin (for staining the cytoplasm);

5) hematoxylin (for staining nuclei);

6) glycerin (for drug enlightenment).

Cell- the basic structural and functional unit of the plant body. In unicellular plants, the cell functions as a whole organism; in multicellular organisms, cell differentiation is observed. Therefore, the size, shape and structure of cells in such organisms are very diverse. An adult living plant cell consists of a protoplast surrounded by a cell membrane and containing non-living inclusions (reserve substances and end products of metabolism).

Protoplast- the living contents of the cell - consists of organelles, or organelles, surrounded by hyaloplasm. Organelles can be divided into three groups: two-membrane - nucleus, plastids, mitochondria; single-membrane - endoplasmic reticulum (endoplasmic reticulum - ER), Golgi apparatus (complex), vacuole, lysosomes, plasmalemma; non-membrane - ribosomes, microtubules, microfilaments. Hyaloplasm is a continuous colloidal phase of the cell with a certain viscosity. It surrounds all organelles and ensures their interaction. Hyaloplasm with organelles minus the nucleus and plastids is called cytoplasm.

Core is an essential part of the eukaryotic cell. This is the place of storage and reproduction of hereditary information. The nucleus also serves as the control center for metabolism and almost all processes occurring in the cell. Outside, the nucleus is covered with a double membrane - a nuclear membrane pierced by pores, at the edges of which the outer membrane passes into the inner one. The internal content of the nucleus is karyoplasm with chromatin and nucleoli embedded in it, and ribosomes.

Mitochondria are present in all living eukaryotic cells. Their inner membrane forms outgrowths into the cavity of the mitochondria in the form of plates or tubes, called cristae. The space between the cristae is filled with a homogeneous matrix. The matrix contains ribosomes and its own DNA. The main function of mitochondria is to provide the energy needs of the cell through respiration.

plastids organelles found only in plant cells. They are represented by chloroplasts (green), chromoplasts (yellow, orange, red-orange) and leucoplasts (colorless). Chloroplasts have a two-membrane membrane. The inner membrane protrudes into the cavity of the chloroplast with a few outgrowths. Between the outgrowths is the stroma. Outgrowths and stroma form a complex system of membrane surfaces in the chloroplast cavity, delimiting special flat sacs called thylakoids or lamellae. Tillakoids form stacks - grains. The thylakoid membranes contain the main pigment of green plants - chlorophyll and auxiliary pigments - carotenoids.

Endoplasmic reticulum- a three-dimensional system of vacuoles and tubules, in the form of flat sacs or tanks. Rough ER is the site of protein synthesis and is covered with numerous ribosomes. The smooth ER is devoid of ribosomes and serves as a site for the formation of lipids.

Vacuoles cavities in the protoplast of eukaryotic cells. Vacuoles are derivatives of EPS, bounded by a membrane - tonoplast and filled with watery contents - cell sap. In young plant cells, vacuoles represent a system of tubules and vesicles (pro-vacuoles), as the cells grow, they increase and merge into one large vacuole. It occupies 70-90% of the cell volume, and the protoplast is located in the form of a thin wall layer. Basically an increase in cell size
occurs due to the growth of the vacuole. As a result, turgor pressure arises and the elasticity of cells and tissues is maintained.

cell sap is an aqueous solution of mineral salts and various organic compounds: carbohydrates (mono-, di- and polysaccharides), proteins, organic acids and their salts (the most common are citric, malic, succinic, oxalic acids and their derivatives), alkaloids (nitrogen-containing compounds , many of which are plant poisons, some are used by humans - caffeine, atropine, quinine, morphine, codeine), tannins (phenolic derivatives), glycosides (sugar derivatives). Among the latter, the most interesting group is flavonoids (these are pigments of two primary colors: flavones - yellow and anthocyanins - red-violet). Most often, flavonoids are found in the perianth cells of flowers, to which they give a variety of colors. Interestingly, anthocyanins are able to change color depending on the reaction of the cell sap: when slightly acidic, they are red, and when neutral or basic, they are blue-violet. A change in the color of anthocyanins can be observed when the flowers of forget-me-not, lungwort or rough comfrey open. The buds of these plants have pink corollas, while the opened flowers are blue or purple. In addition to the petals, anthocyanins can be found in other parts of the plant - leaves, stems, roots, giving them a characteristic color.

golgi apparatus consists of individual dictyosomes and Golgi vesicles. Dictyosomes are stacks of flat disc-shaped cisterns that do not touch each other and are bounded by membranes. The Golgi vesicles are detached from the edges of the dictyosome plates or the ends of the tubes and directed towards the plasmalemma or vacuole. Golgi vesicles transport the resulting polysaccharides.

State budget educational institution

Higher professional education

"Bashkir State Medical University"

Ministry of Health and Social Development

Russian Federation

Department of Pharmacognosy with a course of botany and the basics of herbal medicine

"9" _ September _____2012

Discipline Botany Speciality 060301 Pharmacy

Well 1 (full-time department) Semester 1

Section: “The doctrine of the cell. Ergastic and secretory substances in the plant cell

Lab #1

Presentation on theme: "Optical microscopes. Features of botanical microtechnology. Osmotic properties of the plant cell

Lab #2

Presentation on theme: "The structure of the cell wall. Plastids, spare and mineral inclusions"

students

Ufa 2012
Lab #1

Topic of the lesson: “Optical microscopes. Features of botanical microtechnology. Osmotic properties of the plant cell

1. Relevance. The study of methods of botanical microtechnics is a prerequisite for mastering practical skills in the section "Cytology, histology and anatomy of plants." The study of the structure of a plant cell and its osmotic properties gives an idea of ​​the cellular organization of plant organisms, structural features and differences from animals.

2. Objectives of the lesson:

1. Acquire the skills of working with a microscope;

2. Acquire the skills of preparing temporary micropreparations

3. Acquire the skills of botanical microtechnology for microscopic analysis of whole, cut and powdered medicinal plant materials;

4. Study the structural features of a plant cell

5. Study the properties of a plant cell

know :

The device of the microscope and the rules for working with it;

· the history of the study of the cell, the postulates of cell theory;

The structure of a prokaryotic cell

The structure of the eukaryotic cell, its main organelles;

Features of the structure of the plant cell.

For the formation of professional competencies, the student must be able to :

prepare a micropreparation;

Examine the micropreparation at low and high magnification of the microscope;

find the organs of the cell;

· carry out the reactions of plasmolysis and deplasmolysis, give a theoretical justification;

For the formation of professional competence, the student must own :

Botanical conceptual apparatus;

· technique of microscopy and histochemical analysis of micropreparations of plant objects.

3. Necessary basic knowledge and skills:

modern ideas about the structure of prokaryotic and eukaryotic cells, their differences.

microscope device.

4. Duration of extracurricular work– 2 academic hours (90 min).

Questions for self-preparation:

1. Microscope. Mechanical and optical systems.

2. Rules for working with a microscope

3. Working distance. Resolution. General increase.

4. Cell. History of study. cell theory

5. The difference between a plant cell and a fungus and animal cell

6. The structure of the cell. Core, structure, functions.

7. Plant cell organelles. Structure, functions

8. Cytoplasm. Structure, functions

9. Vacuole, structure, functions

Explanation for tasks

Microscope.

Microscope - an optical-mechanical system that allows you to get a greatly enlarged image of objects whose dimensions lie far beyond the resolution of the naked eye. The resolution of the eye is 0.15 mm. The resolution of light microscopes is 300-400 times higher than the resolution of the naked eye and is equal to 0.1-0.3 microns.

In a microscope, optical and mechanical systems are distinguished. The optical system consists of an illuminator, a lens and an eyepiece. The mechanical system consists of a revolver, a tube, a tripod, an object table, macro and micro screws.

The lighting apparatus includes:

Condenser (designed for the best lighting, image sharpness control);

Iris diaphragm (designed to regulate the diameter of the light beam and the depth of the field of view);

Mirror (designed to direct rays from the light source to the condenser).

The lens is the most important part of the optical system. The lens gives an image of the object with the reverse arrangement of parts. At the same time, it reveals (“resolves”) structures that are inaccessible to the naked eye.

The eyepiece is used to observe the image built by the lens. The aperture of the eyepiece defines the boundaries of the field of view. In general, the objective and the eyepiece both provide the resolving power of the microscope and determine the total magnification of the microscope (the total magnification of a microscope is defined as the product of the magnification of the objective eyepiece).

The mechanical system of the microscope is designed to mount parts of the optical system.

Working with a microscope

1. Install the microscope opposite the left shoulder, make room in front of you for the album. Put the lens in working position. The correct installation of the lens should be judged by the click that is felt when the revolver is rotated. The distance between the objective and the slide should be about 1 cm. Always start working with a microscope at a low magnification.

2. Fully open the aperture. Raise the condenser to the level of the stage. Aim the light with a concave mirror so that the entire field is illuminated brightly and evenly.

3. Put the prepared micropreparation on the stage so that one of the sections is located exactly under the objective. To fix the micropreparation, press the slide with a clamp.

4. Using the macro screw, set the required focal length to obtain a clear image in the microscope. Correct the distance with a microscrew.

5. Before transferring the microscope to a higher magnification, select the desired cut point, place it in the center of the field of view, and only then change the objectives by carefully rotating the revolver.

6. After finishing work, you need to transfer the microscope to a low magnification and remove the micropreparation.

7. After use, the microscope should be closed with a cap to protect or dust.

Method for preparing temporary micropreparations

1. The object must be taken in the left hand and clamped with three fingers, in the right hand it is necessary to hold a safety razor or blade.

2. Align the surface of the object so that the cut plane is perpendicular to the axis of the organ. Slices are made by moving the razor towards you.

3. Apply 2-3 drops of water to the middle of the slide with a pipette and transfer the thinnest sections at the tip of the dissecting needle, cover the object with a cover slip. Liquid must not leak from under the coverslip.

4. Put the prepared preparation on the object table, examine it at low and high magnifications.

5. In addition to temporary preparations, permanent preparations are used to study objects. The inclusion liquid in them is glycerin with gelatin or Canadian balsam.

6. When staining the drug, it should be taken into account that under the action of concentrated acids, organic inclusions in the cell can be charred, mineral inclusions (crystals, druses, cystoliths) can completely disappear or change their shape.

7. You can not remove the drug from under the x40 lens, because. its working distance is 0.6 mm and it is easy to spoil the front lens.

Cell

The cell is the basic structural and functional unit of all living things. Cells were first described by Robert Hooke in the mid-seventeenth century (1665) while examining a piece of cork. Knowledge of the cell expanded with the improvement of the microscope. By the middle of the nineteenth century, enough knowledge about the cell had been accumulated - the discovery of the nucleus, plastids, cell division, etc. All knowledge about the cell was summarized at the turn of the 30-40s of the 19th century by the botanist M. Schleiden and the zoologist T. Schwann in the form of cell theory.

The main theses (postulates) of the cell theory:

1. cell - a structural and functional unit of all living things;

2. a multicellular organism is a complexly organized, integrated system consisting of functioning and interacting cells;

3. all cells are homologous in structure;

4. "cell from cell." The principle of cell continuity by division was founded in 1958 by the German scientist R. Virchow.

The shape, structure and size of cells are very diverse. The plant cell is made up of protoplast, membrane or cell wall and vacuole.

Protoplast includes: cytoplasm, nucleus, plastids, mitochondria.

Cytoplasm- part of the protoplast between the plasma membrane and the nucleus. The basis of the cytoplasm is its matrix, or hyaloplasm- a complex, colorless colloidal system. The most important role of hyaloplasm is to unite all cellular structures into a single system, ensuring interaction between them in the processes of cellular metabolism. Most of the processes of cellular metabolism are carried out in the cytoplasm, except for the synthesis of nucleic acids.

Core- an obligatory and main part of the living cell of all eukaryotes. Functions of the nucleus: storage and reproduction of hereditary information, control of metabolism and almost all processes occurring in the cell, nucleic acid synthesis, protein synthesis. The nucleus is surrounded by a membrane consisting of two membranes bearing very large pores. The internal contents of the nucleus are called nuclear sap, or nucleoplasm. One or more nucleoli are immersed in the nuclear juice.

Mitochondria cell organelles, the shape, size and number of which are constantly changing. The main function is to provide the energy needs of the cell by oxidizing energy-rich substances (sugars) and synthesizing ATP and ADP. Mitochondria are surrounded by two membranes, the inner one forms outgrowths - cristae. Mitochondria, like plastids, are semi-autonomous organelles, because contain DNA and ribosomes in the matrix.

plastids characteristic only of plants. There are three types of plastids: chloroplasts, chromoplasts and leukoplasts. The main function of chloroplasts is photosynthesis, leukoplasts are the storage of nutrients and chromoplasts are the color of flowers and fruits. Chloroplasts consist of a double membrane, matrix, thylakoids combined into grana, DNA, ribosomes, grains of primary starch.

Golgi complex- a system of discoid sacs and vesicles surrounded by membranes. Performs the functions of synthesis, accumulation and isolation of certain polysaccharides (pectins, mucus, etc.), secondary metabolites; the formation of vacuoles and lysosomes; distribution and intracellular transport of certain proteins; participates in the construction of the cytoplasmic membrane.

EPS (endoplasmic reticulum) - membrane-limited system of submicroscopic channels. EPS is divided into smooth and rough. Rough EPS functions: protein synthesis; directed transport of macromolecules and ions; membrane formation; organelle interaction. The function of smooth EPS is the synthesis of lipophilic compounds.

Vacuole- a cavity in a cell surrounded by a membrane (tonoplast) and filled with cell sap. Cell sap is an aqueous solution of various substances - protoplast waste products. Functions of vacuoles: accumulation of reserve substances and slags; maintenance of cell turgor; regulation of the water-salt balance of the cell.

cell wall separates the cell from the environment. It is based on cellulose molecules, which are grouped into microfibrils and fibrils. Cellulose molecules are immersed in a matrix, which consists of polysaccharides with a more branched structure - hemicelluloses and pectins, as well as water. The cell wall is very strong, and at the same time, elastic. Strength is given to it by cellulose molecules, elasticity - by the matrix. The cell wall performs shaping and mechanical functions, protects the protoplast, resists the high osmotic pressure of the vacuole, and substances are transported through the cell wall.

You have purchased your first optical microscope, carefully studied its design, as well as the rules for working with it. It's time to move directly to the study. What are we going to study? To study any object using a light microscope, you must first prepare a micropreparation.

Micropreparation can be temporary or permanent. For cooking temporary drug, it is necessary to first place a drop of water (glycerol, solution, dye, reagent) on a glass slide, and then place the microobject itself in this drop. After that, the drop is covered with a coverslip. The resulting micropreparation is ready for use. Such a temporary preparation can be reused over the next few days if stored properly. Permanent micropreparations, unlike temporary ones, can be stored for years; for this, microobjects are placed in a special balm (celloidin).

By the way, there is one more trick - if the microorganisms that are used as samples in the preparation are too mobile, 1.5% methylcellulose solution can be added to the water, which will slow down their movement.

Micropreparations can be divided into dry and wet. The technique for preparing a wet preparation, that is, a preparation in which the sample cannot do without water in order to remain alive, has been described above. Concerning dry micropreparations, then no water is used for their preparation. A very thin section of the sample is placed on a glass slide and covered with a coverslip. The coverslip can then be lightly pressed down (only do this with rubber gloves to avoid leaving marks).

Sometimes, when preparing micropreparations, a special stain is additionally used, since without staining, some samples are very difficult to study under a microscope. Usually, a solution of iodine and potassium iodide is used as a dye (a solution of "methylene blue" or "crystal violet" can also be used).

The studied samples are divided into those that can be viewed under a microscope as a whole (for example, spores, pollen, and others), and those for the study of which require preliminary cuts. Slides that use whole specimens are called total.

As for cuts, they can be transverse or longitudinal(radial, tangential, paradermal). A transverse cut is made perpendicular to the axis of the organ, and a longitudinal one is made along the radius of the axis of the organ. A tangential cut is made perpendicular to the radius of a cylindrical structure (eg, a stem), and a paradermal cut is made parallel to the surface of a flat structure (eg, a leaf).

The cuts are made with a very sharp blade, which is constantly wetted with water. It is necessary to make several sections at once, from which then choose the thinnest one and place it in the center of the slide in a drop of water using a dissecting needle.

1) Temporary preparations

To study plant objects using a light microscope, it is necessary to prepare a micropreparation. Micropreparations not intended for long-term storage are called temporary. The object under study is placed on a glass slide in a drop of water, glycerin, solution, reagent or dye and covered with a cover slip. Such preparations can be stored for several days by placing them in a humid atmosphere.

2) Permanent preparations

Permanent preparations are prepared according to special methods that ensure their storage for decades. Permanent preparations include smears, total preparations and sections. Smears are used in the study of blood cells, cultures of microorganisms, isolated tissue cells. Total preparations are separate transparent and thin objects. Training sections can be made manually using a razor. However, high-quality sections with a given thickness of 10 ... 22 micrometers are usually made using special devices - microtomes. Such sections are often referred to as microtome preparations. To obtain thinner sections (0.01 ... 0.05 microns, or 10 ... 50 nanometers), ultramicrotomes are used.

Let us briefly consider the main steps in the preparation of permanent preparations.

1. Material fixation. Immediately after the end of fixation, the material is washed with either water (after water fixatives), or 80% alcohol (after alcohol fixatives). The number of changes of flushing fluids - at least 3. Time - up to 24 hours.

2. Dehydration in alcohols of increasing concentration. In parallel, the material is compacted. The successive movement of material through a series of solutions is called wiring. After water fixatives, 8 alcohol changes are used: 20%, 40%, 80%, two changes of 96%, two changes of 100%. After alcohol fixatives - 4 alcohol changes: two changes of 96% and two changes of 100%. In each shift, the material is aged for 1 hour.

3. Enlightenment. This is the impregnation of the material with a paraffin solvent - xylene (benzene, chloroform). The sample is placed for 1 hour sequentially in each of the following solutions: 3 parts alcohol + 1 part xylene, then 2 parts alcohol + 2 parts xylene, then 1 part alcohol + 3 parts xylene, then two changes of xylene.

4. Embedded in paraffin. This is the replacement of xylene with paraffin. The sample is placed in a mixture of xylene and paraffin at a temperature of 55 ... 57 degrees and left in a thermostat at this temperature until the xylene has completely evaporated (from several hours to several days). Then, at a temperature of 55 ... 57 degrees, wiring is carried out through paraffin I (6 ... 12 hours), paraffin II (6 ... 12 hours) and pouring into paraffin III. Paraffins I, II, III differ only in purity: paraffin III is the final medium, which must have the highest purity. As a result, paraffin blocks are obtained, in which material samples are enclosed. These blocks can be cut in any direction.

5. Staining of cuts. Paraffin sections are glued to a clean glass slide. As an adhesive, you can use a mixture of chicken egg protein with glycerin (in a ratio of 1: 2) with the addition of an antiseptic (thymol or phenol). Sections are usually deparaffinized. To do this, glass with glued sections is passed through xylene, alcohols of decreasing concentration (100%, 96%, 80%, 70%) and distilled water. The residence time in each medium is 2...3 minutes. Then stained according to the methods.

6. Dehydration and clearing of stained sections. It is carried out by wiring through alcohols of increasing concentration, and then through xylene.

7. Conclusion in the environment (fill). For long-term storage of drugs, they must be enclosed in an environment that protects the drug from air oxidation and fungal attack. For filling, special resins are used (Canadian balsam, fir balsam), which are dissolved in xylene to the consistency of liquid honey. A drop of this solution is applied to the section and covered with a coverslip.

6. Chemical composition of the cellular substance. Micro and macro elements.

More than 80 chemical elements were found in the composition of the cell, while no special elements characteristic only of living organisms were found. However, only 27 elements know what functions they perform. the remaining 53 elements probably enter the body from the external environment.

1. Macronutrients

They make up the bulk of the substance of the cell. They account for about 99% of the mass of the entire cell. The concentration of four elements is especially high: oxygen (65-75%), carbon (15-18%), nitrogen (1.5-3%) and hydrogen (8-10%). Macroelements also include elements whose content in a cell is calculated in tenths and hundredths of a percent. These are, for example, potassium, magnesium, phosphorus, sulfur, iron, chlorine, sodium.

2. Trace elements These include mainly metal atoms that are part of enzymes, hormones and

other vital substances. In the body, these elements are contained in very small quantities: from 0.001 to 0.000001%; among such elements are boron, cobalt, copper, molybdenum, zinc, iodine, bromine, etc.

3. Ultramicroelements

Their concentration does not exceed 0.000001%. These include uranium, radium, gold, mercury, beryllium, cesium and other rare elements. The physiological role of most of these elements in the organisms of plants, animals, fungi and bacteria has not yet been established.