A microscope slide is a thin flat piece of glass glass, typically 75 by 25 mm (3 by 1 inches) and about 1 mm thick, used to hold objects for examination under a microscope. Typically the object is placed or secured ("mounted") on the slide, and then both are inserted together in the microscope for viewing. This arrangement allows several slide-mounted objects to be quickly inserted and removed from the microscope, labeled, transported, and stored in appropriate slide cases or folders.
Microscope slides are often used together with a cover slip or cover glass, a smaller and thinner sheet of glass that is placed over the specimen. Slides are held in place on the microscope's stage by slide clips or slide clamps.
Contents |
The origin of the concept was a made of ivory or bone, containing specimens held between disks of transparent mica, that would slide into the gap betwen the stage and the objective. These "sliders" were popular in Victorian England until the Royal Microscopical Society introduced the standardized the glass microscope slide.
A standard microscope slide measures about 75 mm by 25 mm (3" by 1") and is about 1 mm thick. A range of other sizes is available for various special purposes, such as 75 x 50 mm and for geological use, 46 x 27 mm for petrographic studies, and 48 x 28 mm for thin sections. Slides are usually made of common glass and their edges are often finely ground or polished.
While plain slides are the most common, there are several specialized types. A graticule slide is marked with a grid of lines (for example, a 1 mm grid) that allow the size of objects seen under magnification to be easily estimated and provides reference areas for counting minute objects. Sometimes one square of the grid will itself be subdivided into a finer grid. Slides for cell counting may have various reservoirs, channels and barriers etched or ground on their upper surface.
|
|
|
The mounting of specimens on microscope slides is oten critical for successful viewing. The problem has been given much attention in the last two centuries, and is a well-developed area with many specialized and sometimes quite sophisticated techniques.
In a dry mount, the simplest kind of mounting, the object is merely placed on the slide. A cover slip may be placed on top to protect the specimen and the microscope's objective, as well as to keep the specimen still and pressed flat. This mounting can be successfully used for viewing specimens like pollen, feathers, hairs, etc.. It is also used to examine particles caught in transparent membrane filters, e.g. in analysis of airborne dust.
In a wet mount, the specimen is placed in a drop of water or other liquid held between the slide and the cover slip by surface tension. This method is commonly used,for example, to view microscopic organisms that grow in pond water or other liquid media, especially when studying their movement and behavior. It is also used to examine physiological liquids like blood, urine, saliva, semen, and vaginal discharge. Care must be taken to exclude air bubbles that would interfere with the viewing and hamper the organisms' movements.
For pathological and biological research, the specimen is often prepared by a compelx process that may involve cutting it into very thin sections with a microtome, denaturing it to prevent decay, removing any water contained in it, staining specific parts of it, and impregnating it with some transparent solid substance. As part of this process the specimen usually ends up firmly attached to the slide.
|
|
Wikis
Facts
Search
