Staining Paraffin Sections 65 



for many years. Stained sections mounted in balsam may remain in 

 perfect condition for 25 years. However, it is nuich more likely that 

 the stain will fade, the balsam will become dark yellow, and may even 

 become cracked and opacjue like dried varnish. In recent years, 

 numerous synthetic resins have been tried as mounting media. (Lillie, 

 AVinkle and Zirkle. 1950). Further experimentation can lie expected 

 in the future and the many possible polymers will be tested. The 

 reader is advised to consult the catalogues of biological supply dealers 

 for the currently recommended resins. 



The affixing of cover glasses should be accomplished quickly and 

 neatly. Remove a slide from the last xylene, and place with tissue 

 upward on a sheet of dry blotting paper. Working rapidly to avoid 

 drying of the tissues, wipe excess xylene from around the sections, put 

 a drop of resin on the tissues and lower a cover glass obliquely onto 

 the resin. A black background aids in seeing and expelling bubbles. 

 If the size of the drop of resin is correctly gauged, there should 

 be no excess resin squeezed out around the edges or over the 

 cover glass. Newly covered preparations must be used with care 

 because the cover glass is easy to dislodge and the tissues may be dam- 

 aged. Drying new slides in the 53°C. oven for one or more days hardens 

 the resin somewhat and permits safer handling of the slides. 



This is a convenient point at which to discuss the repair of 

 damaged slides. It is possible to salvage a slide that has some sound 

 sections as well as some sections that have been damaged by misuse. 

 Place the slide upside down under a low-power objective and locate 

 the damaged sections. Place a mark over each broken section with 

 India ink. Allow the ink to dry thoroughly, and drop the slide into 

 a jar of xylene. After the cover glass has slid off, rub off the damaged 

 section with a matchstick, rinse in xylene, and mount a new cover 

 glass. 



Destaining and Restaining 



Slides may be examined for color at several stages in the staining 

 process, in fact from any reagent that is not so highly volatile that 

 the preparation becomes dry during a brief examination. See page 63 

 for the procedures used to increase or decrease the intensity of the 

 color imparted by hemalum. If the slide is examined out of xylene or 

 carbol-xylene and the stain intensity needs to be increased or 

 decreased, transfer the slide backwards through the dehydrating series 

 to water, and proceed with corrective measures. 



It may be necessary to modify the stain intensity of a finished slide 



