Editing Microscope slide

{{short description|Thin, flat piece of glass onto which a sample is placed to be examined under a microscope}}
{{redirect|Glass slide|text=The term may also refer to [[photographic slide]]s}}
[[File:MicroscopeSlides.jpg|thumb|A set of standard 75 by 25 mm microscope slides. The white area can be written on to label the slide.]]
[[Image:Fedolemez.jpg|240px|right|thumb|A microscope slide (top) and a cover slip (bottom)]]

A '''microscope slide''' is a thin flat piece of [[glass]], typically 75 by 26&nbsp;mm (3 by 1 inches) and about 1&nbsp;mm thick, used to hold objects for examination under a [[microscope]].  Typically the object is [[#Mounting|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==
[[File:Filippo pacini cholera discovery.gif|upright=1.2|thumb|A microscope slide prepared in 1855 containing reference specimens from the inner [[mucosa]] of the [[small intestine]] of a [[cholera]] victim.]]
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.<ref>[https://archive.org/details/esmicrosco00adam Adam, George. Essays on the microscope. 1798]</ref> These "sliders" were popular in [[Victorian-era]] England until the [[Royal Microscopical Society]] introduced the standardized glass microscope slide.<ref name="Bristol">{{cite web|last1=Connett|first1=Jess|title=The art of the invisible|url=https://www.bristol247.com/lifestyle/shops/the-art-of-the-invisible/|website=[[Bristol24-7]]|access-date=29 March 2018|date=4 October 2017}}</ref>

==Dimensions and types==
[[File:Microscope slides.svg|right|thumb|Common dimensions of microscope slides (in mm).]]
A standard microscope slide measures about 75&nbsp;mm by 25&nbsp;mm (3″ by 1″) and is about 1&nbsp;mm thick. A range of other sizes are available for various special purposes, such as 75 x 50&nbsp;mm for [[geological]] use, 46 x 27&nbsp;mm for [[petrographic]] studies, and 48 x 28&nbsp;mm for [[thin section]]s. Slides are usually made of common glass and their edges are often [[ground glass|finely ground]] or polished.

Microscope slides are usually made of optical quality [[glass]], such as [[soda lime glass]] or [[borosilicate glass]], but specialty plastics are also used. [[Fused quartz]] slides are often used when [[ultraviolet]] transparency is important, e.g. in [[fluorescence microscopy]].<ref name=tedpella>
  [http://www.tedpella.com/histo_html/quartz-micro-slides.htm Quartz Microscospe Slides and Cover Slips] from a commercial website (Ted Pella). Accessed on 2010-01-23.
</ref><ref name=spi>[http://www.2spi.com/catalog/ltmic/quartz.shtml Quartz Microscope Slides and Cover Slips] {{Webarchive|url=https://web.archive.org/web/20150810194644/http://2spi.com/catalog/ltmic/quartz.shtml |date=2015-08-10 }} catalog page from a commercial website (SPI Supplies).  Accessed on 2010-01-23.</ref>

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 culture]]s.<ref name=emsdia/>  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.<ref name=emsdia/>

A '''graticule slide''' is marked with a [[wikt:grid|grid]] of lines (for example, a 1&nbsp;mm grid) that allows 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 specialized applications, such as [[hemocytometer]]s for cell counting, may have various reservoirs, channels and barriers [[etching|etched]] or [[ground glass|ground]] on their upper surface.<ref name="lentz">
{{cite web|url=https://www.huidainstrument.com/info/lentz-microscopy-collection-a-marvel-of-histo-96083781.html|title=Lentz Microscopy Collection|access-date=30 May 2024}}
</ref>  Various permanent markings or masks may be [[printing|printed]], [[sand blasting|sand-blasted]], or deposited on the surface by the manufacturer, usually with inert materials such as [[polytetrafluoroethylene|PTFE]].<ref name=tekdon>
  [http://www.tekdon.com/microscope-slides.html  Microscope Slides] catalog page from a commercial website (TEKDON).  Accessed on 2010-01-23.
</ref>
<gallery mode=packed>
File:Neubauer improved counting chamber.jpg|A [[Hemocytometer|Neubauer slide]] for cell counting.
File:Neubauer improved with cells.jpg|Microscope image of a Neubauer slide's graticule being used to count [[Cell (biology)|cells]].
File:Urinary phase-contrast microscopy.jpg|A Neubauer slide held in place on a microscope stand by a slide clamp on a cross-table.
File:Standard and large microscope slide.jpg|Standard (75 x 25&nbsp;mm or 3x1″) and large (75 x 51&nbsp;mm or 3x2″) microscope slide.
</gallery>
Some slides have a [[frosted glass|frosted]] or [[vitreous enamel|enamel-coated]] area at one end, for labeling with a pencil or pen.<ref name=emsdia>
  [http://www.emsdiasum.com/microscopy/products/histology/slides.aspx Histology and Light Microscopy] catalog page from a commercial website (EMS).  Accessed on 2010-01-23.
</ref> Slides may have special coatings applied by the manufacturer, e.g. for chemical inertness or enhanced [[cell adhesion]].  The coating may have a permanent [[electric charge]] to hold thin or powdery samples. Common coatings include [[poly-L-lysine]], [[silane]]s, [[epoxy resin]]s,<ref name=emsdia/><ref name=tekdon/> or even [[gold]].<ref name=asyl>
  [http://www.asylumresearch.com/Products/GoldSlides/GoldSlidesDSHR.pdf Gold Coated Microscope Slides and DNA Imaging Kit]  catalog page from a commercial website (Asylum Research).  Accessed on 2011-08-31.
</ref>

==Mounting==
[[File:5901 lores.jpg|thumb|120px|right|Blood smears for pathological examination, an example of wet mount]]
[[File:Tissue processing - Stained and mounted slides in the ubiquitous 20-slide folder.jpg|thumb|120px|right|Microscope slides with prepared, stained, and labeled tissue specimens in a standard 20-slide folder]]

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 [[image resolution|high-resolution]] microscopes have a very narrow [[depth of field|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 [[surface tension]]) and protects the specimen from dust and accidental contact. It protects the microscope's [[objective lens]] from contacting the specimen and vice versa; in [[Oil immersion|oil immersion microscopy]] or [[Water immersion objective|water immersion microscopy]] the cover slip prevents contact between the immersion liquid and the specimen. The cover slip can be glued to the slide so as to seal off the specimen, retarding [[dehydration]] and [[oxidation]] of the specimen and also preventing contamination.  A number of sealants are in use, including commercial sealants, laboratory preparations, or even regular clear [[nail polish]], depending on the sample.  A solvent-free sealant that can be used for live cell samples is "valap", a mixture of [[vaseline]], [[lanolin]] and [[Paraffin wax|paraffin]] in equal parts.<ref name=ucsd/>
[[Microbial culture|Microbial]] and [[cell culture]]s can be grown directly on the cover slip before it is placed on the slide, and specimens may be permanently mounted on the slip instead of on the slide.<ref name=ucsd>
  [http://cancer.ucsd.edu/research-training/shared-resources/microscopy/Pages/protocols.aspx Microscopy – Protocols] {{webarchive|url=https://archive.today/20130403101628/http://cancer.ucsd.edu/research-training/shared-resources/microscopy/Pages/protocols.aspx |date=2013-04-03 }} teaching webpage by the Moores Cancer Center, University of California at San Diego. Accessed on 2013-02-07.</ref>

Cover slips are available in a range of sizes and thicknesses.<ref name=corning0211>[http://www.tedpella.com/histo_html/coverslip-info.htm GE technical specs] from a commercial website (Ted Pella). Accessed on 2010-01-23.</ref> 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.<ref>{{cite web|title=Coverslip Correction Collars|url=http://olympus.magnet.fsu.edu/primer/java/aberrations/slipcorrection2/index.html|website=Microscopy Resource Center|publisher=Olympus|access-date=4 June 2017}}</ref><ref>Michael W. Davidson (2010), [http://micro.magnet.fsu.edu/primer/java/aberrations/spherical/index.html Optical Aberrations], chapter in [http://micro.magnet.fsu.edu/index.html Molecular Expressions] website at Florida State University. Last edit 2006-06-15 at 02:39 PM, accessed in 2010-01-12.</ref>

===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 technology|membrane filter]]s (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 [[pathological]] and [[biological]] research, the specimen usually undergoes a complex [[histology|histological]] preparation that involves [[fixation (histology)|fixing]] it to prevent decay, [[dehydration|removing any water]] contained in it, replacing the water with [[paraffin wax|paraffin]], cutting it into very thin sections using a [[microtome]], placing the sections on a microscope slide, [[staining (biology)|staining]] the tissue using various stains to reveal specific tissue components, clearing the tissue to render it transparent and covering it with a coverslip and mounting medium.

===Strewn mount===
'''Strewn mounting''' describes the production of [[palynology|palynological]] microscope slides by suspending a concentrated sample in [[distilled water]], placing the samples on a slide, and allowing the water to [[evaporate]].<ref name="ref_1485913">{{cite journal |last=Zippi |first=Pierre A. |year=1991 |title=SEM and Light Microscope Mounting and Specimen Location Technique for Same-Specimen Study of Palynological Strew Mounts |journal=Micropaleontology |volume=37 |issue=4 |pages=407–13 |doi=10.2307/1485913 |jstor=1485913|bibcode=1991MiPal..37..407Z }}</ref>

===Mounting media===
The '''mounting medium''' is the solution in which the specimen is embedded, generally under a cover glass. Simple liquids like water or [[glycerol]] can be considered mounting media, though the term generally refers to compounds that harden into a permanent mount. Popular mounting media include ''Permount'',<ref name="permount">{{cite web|url=https://research.amnh.org/molecular/histology_lab_msds/histology_msds/permount_mounitng_media.pdf|title=Material Safety Data Sheet, Permount Mounting Media|access-date=29 March 2018}}</ref> and [[Chloral hydrate#Hoyer.27s mounting medium|Hoyer's mounting medium]] and an alternative ''glycerine jelly'' <ref name="Mobot">{{cite web|title=Glycerine Jelly as a Substitute for Hoyer's Solution Mountant|url=https://www.mobot.org/plantscience/resbot/Meth/GlycerinJellyB.htm|website=www.mobot.org|access-date=29 March 2018}}</ref>   Properties of a good mounting medium include having a [[refractive index]] close to that of glass (1.518), non-reactivity with the specimen, stability over time without crystallizing, darkening, or changing refractive index, solubility in the medium the specimen was prepared in (either [[aqueous]] or [[non-polar]], such as [[xylene]] or [[toluene]]), and not causing the specimen stain to fade or leach.<ref>[https://books.google.com/books?id=lciNs3VQPLoC&pg=PA446 Medical Laboratory Science : Theory And Practice] By Ochei & Kolkatker, p. 446.</ref>

====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<ref>[http://www.gonda.ucla.edu/bri_core/mounting.htm Fluorescence specimen mounting, mounting medium, and antiquench agents – UCLA Brain Research Institute]</ref>
##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=====
[[File:Journal.pone.0079155.g001 Slide of holotype of Lethacotyle fijiensis Manter & Prince, 1953.png|thumb|Slide of 60-year-old [[holotype]] specimen of a flatworm (''[[Lethacotyle fijiensis]])'' permanently mounted in [[Canada balsam]]]]
Used when a permanent mount is required
# Permount (toluene and a polymer of a-pinene, b-pinene, dipentene, b-phellandrene)
# [[Canada balsam]]
# DPX (''D''istrene 80 – a commercial [[polystyrene]], a [[Plasticizer|''p''lasticizer]] 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 [[specimen preservation]] in glass containers in museums. However an entirely different type of mounting is done for [[Electron microscope#Sample preparation|sample preparation]], which can be for biological or nonbiological materials and is further subdivided into "hot"(compressive) and "cold" (castable) type mounting processes.<ref>[http://www.emsdiasum.com/microscopy/products/materials/embedding.aspx Cold and Hot Mounting Media, Molds, and Pressure Chamber – Electron Microscopy Sciences]</ref><ref>[http://www.alliedhightech.com/mounting/ Allied High Tech – Allied High Tech Products | Metallographic Mounting Equipment<!-- Bot generated title -->]</ref> Though named "mounting", it is more akin to embedding in histology and should not be confused with the mounting described above. The term mounting in other fields has numerous other meanings.

==See also==
*[[Petri dish]]

==References==
{{Reflist|2}}

{{Wikibooks|School Science|Microscope slide}}

{{DEFAULTSORT:Microscope Slide}}
[[Category:Microscopy]]
[[Category:Laboratory glassware]]