A wet mount is probably the simplest way to prepare a specimen for microscopic examination. Just place a drop of liquid containing micro-organisms on a microscope slide and place a cover-slip (a square thin glass) on top of it. But such simple wet mounts dry out quickly. For more extended viewing, a hanging drop mount is made by placing a drop of liquid containing micro-organisms on a cover-slip and suspending it over a depression slide. Petroleum jelly around the wall of the depression slide seals the mount to prevent drying.Wet mounts are used to observe living micro-organisms. For example, wet mounts are routinely used to examine vaginal secretions for Trichomonas vaginalis, a protozoan that causes inflammation of the vagina and urethra. If the specimen contains fish-shaped cells that move jerkily across the field, they are most probably T.vagina (Murray, 1997). But many micro-organisms lack sufficient contrast to be clearly visible in a wet mount viewed with an ordinary bright field light microscope. To visualize them, it’s necessary to increase the contrast either by staining the specimen or using a microscope that generates contrast by different means.In general, light microscopes are for everyday use. Specimen preparation and operation are relatively rapid and simple. Light microscopy provides valuable information about the size, shape and general appearance of cells. However, resolution is limited and therefore so. Light Microscopy.
Gephardt, P. 1994. Methods of General Microbiology, Washington, D.C: ASM Press.
James, J & Tanke, H. J. 1991. Biomedical Light Microscopy, Boston: Kluwer, pp.11-15.
Murray, P. R. 1997. Manual of Clinical Microbiology, 7th Ed, Washington D.C: ASM Press, pp.32-33.
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