Section Cutting and Staining: A practical introduction to histological methods for students and practitionersColman, Walter S.
Science
Section Cutting and Staining: A practical introduction to histological methods for students and practitioners
Colman, Walter S.
Microscopy
In this method the section whether stained or unstained is placed in a
bowl of water, or normal salt solution (p. 53). A clean slide is then
introduced into the water at an angle of about 60°, a little more than
half of its length being submerged. The section is then brought up by
the needle and floated as far as possible into position on the slide.
One corner is then fixed by the needle, and on gently withdrawing the
slide the section should lie flat. If any folds are left no attempt
should be made to smoothen them out with a needle, but the slide should
be re-immersed until the folded part of the section is under water. It
should then be gently withdrawn, when the fold will disappear. This
manœuvre must be repeated in different directions until the section
lies quite smoothly on the slide. Stained and unstained sections are
floated out in this way before being mounted in Farrant’s medium, and
unstained sections previous to staining in picrocarmine.
2. By *transference* with a *section lifter*.
This method is employed in mounting in Canada balsam in order to
transfer the section from the clarifying agent (p. 63) to the slide.
The lifter is polished, and insinuated under the section. The section
being held in position by the needle is now raised from the fluid,
excess of which is removed by holding the section in position with a
mounted needle, and tilting the lifter so as to allow it to drain off.
*Removal of air bubbles from sections.*--When sections contain many
air bubbles, the best plan is to leave them in methylated spirit for a
time. The bubbles then coalesce and escape from the section.
For delicate structures and for fresh sections the transference to
spirit, and the subsequent flying out of the section when returned to
water are risky, and the best method of treating these is to put the
vessel containing them under the receiver of an air pump, if one is
available, and slightly exhausting the air.
The most frequent cause of air bubbles in mounted specimens, however,
is the employment of cover-glasses which have not been thoroughly
cleansed. Proper cleansing is best effected by placing the covers when
bought in a shallow wide mouthed stoppered bottle containing strong
nitric acid, and leaving them in this fluid for twenty-four hours. The
acid should then be drained off and water run through the vessel from
a tap, until the washings no longer give an acid reaction with litmus
paper. The water should then be drained off, and the glasses covered
with absolute alcohol. They can be removed one by one and rapidly dried
as required. With cover-glasses properly cleansed in this manner, not
only will air bubbles be avoided, but the covers will be dried much
more easily with the cloth, and fewer will be broken in the process.
Public-domain text, read in full here on John Shaqi.
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