Manual of basic techniques for a health laboratory - libdoc.who.int

176 Manual of basic techniques for a health laboratory●Timer● Giemsa stain (reagent no. 29)●●Methanol in a drop bottleBuffered water, pH 7.2 (reagent no. 15) or distilled water.Fig. 4.136 Placing the slides in a stainingtroughRoutine method for staining thick and thin blood filmsIdeally, for optimum staining, thick and thin films should be made on separateslides. This is often not possible and thick and thin films are generally made on thesame slide. When this is done, good-quality staining of the thick film is of primaryimportance. Best results are obtained if the blood films have dried overnight.This method is suitable for staining 20 or more slides.1. Fix the thin film by adding three drops of methanol, or by dipping it into acontainer of methanol for a few seconds. With prolonged fixation it may be difficultto detect Schüffner’s dots and Maurer’s clefts. To permit dehaemoglobinization,the thick film should not be fixed; therefore avoid exposure of the thick film tomethanol or methanol vapour.2. Using forceps, place the slides back to back in a staining trough (Fig.4.136).3. Prepare a 3% Giemsa solution in buffered or distilled water, pH 7.2,in sufficient quantity to fill the number of staining troughs being used.Mix the stain well.4. Pour the stain gently into the staining trough, until all the slides aretotally covered. Stain for 30–45 minutes out of sunlight.5. Pour clean water gently into the trough to remove the deposit on thesurface of the staining solution (Fig. 4.137).6. Gently pour off the remaining stain (Fig. 4.138), and rinse again inclean water for a few seconds. Pour the water off.Fig. 4.137 Pouring clean water into thestaining trough to remove thedepositFig. 4.138 Pouring off the remainingstainIn some laboratories with limited supplies the diluted Giemsa stain is reused; insuch cases it must be used on the same day.7. Using forceps, remove the slides one by one. Place them in a slide rack to drainand dry, film side downwards, making sure that the film does not touch the sliderack.Rapid method for staining thick and thin blood filmsThis method is suitable for rapid staining of thick films when urgent results arerequired. It uses much more stain than the regular method.