Monday, December 21, 2009

Preparation of permanent slides-pharm-dlabmanual

Preparation of permanent slides-

To prepare a permant slide

A plate or slip of glass on which is a picture or delineation to be exhibited by means of a magic lantern, stereopticon, or the like; a plate on which is an object to be examined with a microscope. Slide mounting of small or rare specimens provides the most permanent and most secure means of long-term storage while allowing easy access for study. Slides mounts allow the quick comparison of many specimens and they insure the label data stays associated with the specimens. Slides can be viewed under either a dissecting microscope or under with a compound microscope. They may be viewed lighted from above or with transmitted light. The biggest disadvantage is that the specimens cannot be moved once the slide is made.
There are two different types of microscope slides in general use. The common flat glass slide, and the depression or well slide. Both are rectangular and measure approximately 1 x 3 inches (25 x 75 mm). Depression slides have an indentation in the center to hold a drop of liquid, cost considerably more than the flat variety, and are usually used without a cover slip.

The best permanent slides use Canada balsam or synthetic resin substitutes in xylene


When preparing microscope slides for observation, it is important first to have all necessary materials on hand. This includes
cover slips,
droppers or
pipets and
any chemicals
or stains
1)The most common slide preparation is called the "wet mount" slide and utilizes a flat slide and a cover slip.
2)prepare a sample of bacterial culture consiting ecoli
3))To make one, place a drop of the sample prepared in the middle of a clean slide and lower a cover slip gently over the drop at an angle, with one edge touching the slide first .
4)) Allow the liquid to spread out between the two pieces of glass without applying pressure. It takes some practice to determine just how much liquid to use.
NOTE:If too much is placed on the slide, the cover slip will "float", creating a water layer that is too thick (allowing protozoans to swim up and down, in and out of focus). If too little liquid is used, the organisms may be crushed by the cover glass and evaporation will dry up the specimens quickly.
A well prepared slide will last for 15 -30 minutes before it dries up.
5)To extend the life of a wet mount slide, scrape petroleum jelly onto each of the four edges of the cover slip.
6) use a cover slip with larger specimens, add a few broken bits of cover glass to the water drop
Note:Many protozoans move too quickly for accurate observations. Larger ones (i.e., Paramecium) can be "corralled" by adding a few strands of cotton fiber from a cotton ball or swab to the drop of the sample before lowering the cover slip.
Staining techniques can be employed to aid in the observation of cell parts. "Non-vital staining" is the staining of dead cells or tissues. "Vital staining" is the staining of live cells.
7)Final Steps
The slides should be marked with the label code and kept flat and undisturbed in a dust free area. They may take weeks to completely dry, but this is greatly accelerated in a small oven at very low heat (barely too hot for prolonged hand contact). A permanent label should be glued to the slide as soon as the slide is cured.
A permant slide with bacterial culture is preperaed and observed under microscope claerly

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