SECTION ADHESIVES

It is advisable to use an adhesive to promote tissue attachment to the glass slides used in histological preparation. This is routinely achieved by the application of a smear of glycerin/albumen mixture to the slide before the section is mounted and dried. However, this does not always provide a strong enough bond and the section may become detached from the slide during the staining procedure. Sections mounted on slides coated by one of the following methods are much more likely to remain attached during the more "aggressive" histological techniques. It should be noted that gelatine gives a positive reaction with some methods and that poly-l-lysine is expensive hence the routine use of glycerin/albumen.  For very fragile sections and some methods it may be necessary to coat the slide with a protective film of celloidin.  

PREPARATION OF POLY - l - LYSINE COATED SLIDES Put the slides in racks and wash thoroughly in soapy water, rinse in tap water and finally rinse in distilled water. Dilute poly - l - lysine 1:10 in distilled water or allow previously prepared solution to reach room temperature. (See 5.) Place racks of slides in the solution leave for 5 mins. Drain slide racks on blotting paper and either dry at 60o C for 1 hour (use photographic drying cabinet), or leave to dry for 18 hours at room temperature covered with foil to keep off dust. Filter the used poly - l - lysine solution and store at 4o C for future use. (It is stable for several months. Discard the solution upon any sign of mould growth). Bring to room temperature before use. PREPARATION OF GELATINISED SLIDES Put the slides in racks and wash thoroughly in soapy water, rinse in tap water and finally rinse in distilled water. Immerse the slide racks in hot gelatine solution...0.5% gelatine in distilled water at 60-80o C. Leave for a few seconds for slides to warm up. Drain the slide racks on blotting paper and remove excess gelatine solution by tipping the racks and allowing it to run off the slides. Dry overnight at 37o C. Store at room temperature. PREPARATION OF ORGANOSILANE (AES) TREATED SLIDES Put the slides in racks and wash thoroughly in soapy water, rinse in tap water and finally rinse in distilled water. Allow the slides to dry completely . Prepare a 2% solution of 3-aminopropyltriethoxy-silane (AES) in acetone in a dry staining dish. Immerse the slides in the AES solution for 2 minutes. Rinse the slides in two changes of distilled water. Dry the slides at 37o C for two hours. Slides may be stored at room temperature. Note: AES slides can often be used in place of poly-l-lysine treated slides and are less expensive to prepare. CELLOIDINIZATION OF SECTIONS Prepare a 1% solution of celloidin in a mixture of equal parts of ethanol and ether. Dewax the sections and rinse in alcohol. Place the slides in a coplin jar of the celloidin solution and leave for 5 minutes. Remove the slides, wipe the backs to remove excess celloidin and place immediately in 80% alcohol for 5 minutes. Rinse briefly in water and continue with the chosen technique. The celloidin film will slowly dissolve in the dehydrating alcohol step at the end of the method. If the film proves difficult to remove use a mixture of equal parts of ethanol and ether