Preparation methods for optical and electron microscopy samples
Microscopic preparation methods generally include four categories: sectioning method, whole mount method, smear method and tableting method.
①Slicing method. The slice thickness of an optical microscope is between 2 and 25 microns. Generally, a slice thickness of about 10 microns for animal and plant materials is appropriate. Sectioning methods vary depending on the embedding medium. Commonly used are paraffin sectioning method, cotton colloid sectioning method, frozen sectioning method, and ethylene glycol methacrylate method (referred to as GMA method). The paraffin sectioning method includes steps such as fixation, embedding, sectioning, staining, dehydration and mounting. The key is to embed the biological material in paraffin, use paraffin as a support, and cut the biological material immersed in the wax block into ideal thin slices. The operation process is: fixation → water washing → alcohol dehydration step by step from low concentration to high concentration → xylene transparency → wax dipping → embedding → sectioning → patch → xylene dewaxing → step by step alcohol treatment from high concentration to low concentration. Finally, it transitions to water → dyeing → stepwise dehydration from low concentration to high concentration alcohol → xylene transparency → resin glue sealing. The basic steps are the same across all production techniques.
②Integral sealing method. Whole-mount preparation method for single cells, tiny organisms, or dispersed organs. This method also requires various steps of fixation, staining, dehydration, transparency and mounting. This method is used to prepare paramecia and insect mouthparts.
③Smear method. A preparation method in which easily dispersed biological specimens are spread on a glass slide. A blood smear is one example.
④Tablet pressing method. Place natural and easily dispersed tissues or tissues that are easily dispersed after processing, such as animal spermatocytes and root tip cells, on a glass slide, add a cover slip, and crush the tissue with force to make the cells or cells inside The structure is spread into one layer of production method. The pressing method is often used to observe chromosomes, usually stained with magenta acetate, lichen red and carbolic fuchsin.
