Smears

Smears in bacteriological and hematological (see Blood) technique represent material spread in a thin layer and dried on a glass slide. Subsequently, smears are usually subjected to fixation, staining, and microscopic examination. At present, smears are prepared exclusively on glass slides, since cover glasses are very fragile. 1) Smears from sputum - see Sputum. 2) Smears from liquid material (pus, exudates, liquid pus, etc.): a) if flakes or threads are floating in the liquid, they can be picked up with a pipette and spread on a glass slide or b) the material is poured into centrifuge tubes, centrifuged, the liquid layer is quickly decanted, a drop is taken from the sediment with a pipette, it is applied to the center of the slide and spread either between two slides or with the same pipette that was used to collect the sediment. 3) Smears from material delivered on a cotton swab or gauze tampon (plaque or mucus from the throat, nose, purulent content of a wound or ulcer, smears from vaginal mucus to determine menstrual periods in rodents) are prepared by rubbing the center of the slide with all sides of the swab or tampon (the tampon is grasped with sterile forceps); if the swab or tampon has already dried, a small drop of water is first applied to the slide. 4) Smears from the delicate film forming on the surface of cerebrospinal fluid: a) carefully with a sterile platinum loop, touching only the surface of the fluid, the film is removed and a small spot is spread on the center of the slide or b) in a Petri dish, the slide is placed in a slightly inclined position, the fluid with the film is poured onto the surface of the slide, the fluid drains off, while the film remains on the slide. 5) Smears from the base of an ulcer for examination for Treponema pallidum (Schaudinn); the ulcer is washed with a cotton swab moistened with physiological NaCl solution; with a heated and cooled loop, the edges of the ulcer are slightly irritated until a clear serum exudes from under the edges: the serum is collected on the loop and a smear is made. 6) Smears from pyogenic tissue; the tissue is cut into not too small pieces, soaked in a small amount of physiological solution, the resulting fluid is centrifuged, smears are made from the sediment. 7) Smears from organs: small pieces are cut out and rubbed between two slides or a slide is quickly passed over the fresh surface of the organ's incision; by quickly applying a slide to the surface of the incision, it is possible to obtain impression smears (Klatschpräparat of German authors), for example, of bone marrow. 8) Smears from blood - see Blood. 9) Smears from feces; if there are particles of mucus or pus, if not, then particles from the surface and from the center of the delivered feces are spread between two glass slides. 10) Smears from liquid culture; with a sterile platinum loop or a Pasteur pipette, a drop of culture is collected and applied to the slide; if the culture grows on the bottom of the nutrient medium (e.g., streptococci), the Pasteur pipette with a rubber bulb squeezed in the hand at its upper end is inserted, the pipette is brought to the bottom, the bulb is slightly released so that a drop of culture enters the pipette tip, and without releasing the bulb further, the pipette is withdrawn from the nutrient medium; further procedure is as described above. 11) Smears from solid nutrient medium; with a sterile platinum loop or the sealed end of a Pasteur pipette, a specific colony is removed or the entire surface of the nutrient medium is carefully passed over so as not to remove the nutrient medium; the removed material is introduced into a drop of water applied to the center of the slide and spread in the form of a small round spot. 12) Impression preparation (Klatschpräparat of German authors); a clean, sterilized cover glass is placed on the colony to be examined (the culture is grown in a Petri dish); the surface of the cover glass is slightly pressed with forceps; when it becomes noticeable that the glass has touched the colony, it is carefully removed from the dish with thin forceps. 13) Unfixed smears; particles of the material to be examined are placed on the center of a glass slide and, without spreading, are covered with a clean cover glass: by slightly pressing on the center of the cover glass with forceps, the material is distributed in a thin, even layer and in this form (before the preparation dries) it is examined microscopically.