Plain slides are the most basic but there are several other types. Frosted end slides
make them easy to write on and with manufacturing volumes efficiencies this process is
inexpensive so that they are more popular than plain slides. A concavity slide or cavity
slide has one or more shallow depressions, or wells, and are designed to hold slightly
thicker objects. These are also used for certain samples such as liquids and tissue
cultures. Slides can have clipped corners for increased safety or for use with a slide
clamp on a microscope. They also tend to avoid slides getting chipped in automated
processes which causes debris in machines.
A graticule slide, or counting chamber, is marked with a grid of lines that allows the
size of objects seen under magnification. This allows you to reference areas for
counting minute objects.
Slides are now available with coloured ends for identification and allow print from slide
inkjet or thermal printers.
For small specimens that don’t easily adhere special coatings can be applied by the
manufacturer for chemical inertness or enhanced cell adhesion. The coating may have a
permanent electric charge to hold thin or powdery samples or poly-L-lysine, silane to
The properties of a slide is important although mostly the way slides are packed and
stored is the cause of problems. Change in temperature causes moisture which creates a
‘sticking effect’. This can be identified with a rainbow pattern seen within a block of
slides. Often placing the slides in a warm place will resolve this issue. It is normal
for manufacturers to allow a certain amount of microscopic glass particles on the slide
in the cleaning process to stop them sticking to each other. This can give the
appearance of ‘dusty’ slides although this shouldn’t cause any background staining and
therefore no effect on the result.
Some slides appear ‘green’ to the eye but generally has no effect on results. Over
hydrophobic and hydrophilic glass causes issues with adhesion with histological samples
Once the slide is prepared mounting of specimens is often critical for successful
viewing. This can be done manually or in an automated process depending on the type.
Dry mounting is the simplest kind of mounting where the object is merely placed on the
slide. A cover slip may be placed on top to protect the specimen while the object is
viewed microscopically while pressed flat. This method can be used for viewing specimens
such as pollen, feathers, hairs or airborne dust.
Wet mounting the specimen is when a drop of water or other liquid held between the slide
and the cover slip by surface tension. This method may be used to view microscopic
organisms that grow in pond water especially when studying their movement.
Prepared mount is used for pathological and biological research. The specimen undergoes
a complex histological preparation that involves fixing it to prevent decay by removing
any water contained in it before infiltrating it with paraffin. Very thin sections are
cut using a microtome to reduce to a depth of three microns which is often the
equivalent of a single cell. Staining the tissue using various stains reveals specific
tissue components and abnormalities such as disease including cancer.
There are various types of mounting media depending on the specimen, process or
preference. These include non-aqueous mountants including xylene or toluene based or