Microscope slide
A microscope slide is a thin flat piece of glass, typically 75 by 26 mm (3 by 1 inches) and about 1 mm thick, used to hold objects for examination under a microscope. Typically the object is mounted (secured) 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 etc.
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, slide clamps or a cross-table which is used to achieve precise, remote movement of the slide upon the microscope's stage (such as in an automated/computer operated system, or where touching the slide with fingers is inappropriate either due to the risk of contamination or lack of precision).
History
The origin of the concept was pieces of ivory or bone, containing specimens held between disks of transparent mica, that would slide into the gap between the stage and the objective.[1] These "sliders" were popular in Victorian England until the Royal Microscopical Society introduced the standardized glass microscope slide.[2]
Dimensions and types
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 are available for various special purposes, such as 75 x 50 mm for
Microscope slides are usually made of optical quality
While plain slides are the most common, there are several specialized types. A concavity slide or cavity slide has one or more shallow depressions ("wells"), designed to hold slightly thicker objects, and certain samples such as liquids and tissue cultures.[5] Slides may have rounded corners for increased safety or robustness, or a cut-off corner for use with a slide clamp or cross-table, where the slide is secured by a spring-loaded curved arm contacting one corner, forcing the opposing corner of the slide against a right angled arm which does not move. If this system were used with a slide which did not incorporate these cut-off corners, the corners would chip and the slide could shatter.[5]
A graticule slide is marked with a
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A Neubauer slide for cell counting.
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Microscope image of a Neubauer slide's graticule being used to count cells.
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A Neubauer slide held in place on a microscope stand by a slide clamp on a cross-table.
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Standard (75 x 25 mm or 3x1″) and large (75 x 51 mm or 3x2″) microscope slide.
Some slides have a
Mounting
The mounting of specimens on microscope slides is often 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. Specimens are often held into place using the smaller glass cover slips.
The main function of the cover slip is to keep solid specimens pressed flat, and liquid samples shaped into a flat layer of even thickness. This is necessary because high-resolution microscopes have a very narrow region within which they focus.
The cover glass often has several other functions. It holds the specimen in place (either by the weight of the cover slip or, in the case of a wet mount, by
Cover slips are available in a range of sizes and thicknesses.[10] Using the wrong thickness can result in spherical aberration and a reduction in resolution and image intensity. Specialty objectives may be used to image specimens without coverslips, or may have correction collars that permit a user to accommodate for alternative coverslip thickness.[11][12]
Dry mount
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 and 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).
Wet mount or temporary mount
In a wet mount, the specimen is placed in a drop of iodine 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 lakes.
Prepared mount or permanent mount
For
Strewn mount
Strewn mounting describes the production of
Mounting media
The mounting medium is the solution in which the specimen is embedded, generally under a cover glass. Simple liquids like water or
Examples of mounting media
Aqueous
Popularly used in immunofluorescent cytochemistry where the fluorescence cannot be archived. The temporary storage must be done in a dark moist chamber. Common examples are:
- Glycerol-PBS (9:1) with antiquench, e.g. any of the following[17]
- p-phenylenediamine
- propyl gallate
- 1,4-Diazabicyclo (2,2,2)-octane (DABCO) (very popular)
- Ascorbic acid
- Mowiol or Gelvatol
- Gelatin
- Mount
- Vectashield
- Prolong Gold
- CyGEL / CyGEL Sustain (to immobilize living, unfixed cells and organisms)
Non-aqueous
Used when a permanent mount is required
- Permount (toluene and a polymer of a-pinene, b-pinene, dipentene, b-phellandrene)
- Canada balsam
- DPX (Distrene 80 – a commercial polystyrene, a plasticizer e.g. dibutyl phthalate and xylene)
- DPX new (with xylene but free of carcinogenic dibutyl phthalate)
- Entellan (with toluene)
- Entellan new
- Hempstead Halide Hoyer's Medium (a proprietary formulation of the traditional Hoyer's medium containing 60% Chloral, but free of known carcinogens)
- Neo-Mount (compatible with aliphatic neo-clear but not compatible with aromatic solvents like xylene)
Contrasting with other types/meanings of "mounting"
In contrast to mounting necessary for glass coverslips, somewhat similar mounting can be done for bulkier
See also
References
- ^ Adam, George. Essays on the microscope. 1798
- Bristol24-7. Retrieved 29 March 2018.
- ^ Quartz Microscospe Slides and Cover Slips from a commercial website (Ted Pella). Accessed on 2010-01-23.
- ^ Quartz Microscope Slides and Cover Slips Archived 2015-08-10 at the Wayback Machine catalog page from a commercial website (SPI Supplies). Accessed on 2010-01-23.
- ^ a b c d Histology and Light Microscopy catalog page from a commercial website (EMS). Accessed on 2010-01-23.
- ^ "Lentz Microscopy Collection" (PDF). Retrieved 29 March 2018.[permanent dead link]
- ^ a b Microscope Slides catalog page from a commercial website (TEKDON). Accessed on 2010-01-23.
- ^ Gold Coated Microscope Slides and DNA Imaging Kit catalog page from a commercial website (Asylum Research). Accessed on 2011-08-31.
- ^ a b Microscopy – Protocols Archived 2013-04-03 at archive.today teaching webpage by the Moores Cancer Center, University of California at San Diego. Accessed on 2013-02-07.
- ^ GE technical specs from a commercial website (Ted Pella). Accessed on 2010-01-23.
- ^ "Coverslip Correction Collars". Microscopy Resource Center. Olympus. Retrieved 4 June 2017.
- ^ Michael W. Davidson (2010), Optical Aberrations, chapter in Molecular Expressions website at Florida State University. Last edit 2006-06-15 at 02:39 PM, accessed in 2010-01-12.
- JSTOR 1485913.
- ^ "Material Safety Data Sheet, Permount Mounting Media" (PDF). Retrieved 29 March 2018.
- ^ "Glycerine Jelly as a Substitute for Hoyer's Solution Mountant". www.mobot.org. Retrieved 29 March 2018.
- ^ Medical Laboratory Science : Theory And Practice By Ochei & Kolkatker, p. 446.
- ^ Fluorescence specimen mounting, mounting medium, and antiquench agents – UCLA Brain Research Institute
- ^ Cold and Hot Mounting Media, Molds, and Pressure Chamber – Electron Microscopy Sciences
- ^ Allied High Tech – Allied High Tech Products | Metallographic Mounting Equipment