Editing Microscope slide (section)

==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)