Re: grids for cell counting
|From:||RUSS ALLISON <Allison@Cardiff.ac.uk>|
There are two possibilities open to you (sorry, three but I assume
superimposing a grid thru you software is one you have thought of).
Microscopically, it depends upon whether you are counting a "wet
preparation" or a dry slide.
For the former, there are "counting chambers" which are accurately
made and carefully calibrated and inscribed. Thr result is they are
of a known depth (between the slide surface and the underside of a
coverslip (coverglass) and have, in the business part of the slide, a
(usually) one mm square area inscribed with 10x10 divisions.
The counting chamber is "loaded" by capillary attraction -
manually. There are two common types:- Fuchs-Rosenthal
(0.2mm depth) and improved Neubauer (0.1 mm deep).
Thus you know the area and the depth and hence the volume -
simple mathematics - if there is such a thing! and you have
gridlines to help count. You will receive instructions on the cunning
way to know which (mini) squares you have counted.
The alternative for counting a "dry" preparation is an eyepiece
graticule and slide micrometer. The later allows you to calibrate
the graticule - which, as the name implies, resides within the
eyepiece (or camera tube mount) (you will find a "ledge" therein on
which it should sit and foregive me if I am teaching grandmother
how to suck eggs - did she really do that?)
Then its simple maths - or PC program again, remembering to
repeat the callibration exercise for each objective you use.
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