Do not touch the specimen's surface!!! A well polished, unetched specimen will exhibit just a few structural characteristics such as inclusions, fissures, or other physical flaws under a microscope. Etching is a technique used to emphasize and, in certain cases, detect microstructural characteristics or phases. If you attempt to view the specimen before etching it, you may be misled by its appearance.
Polishing removes material from the surface of the specimen, revealing the underlying structure. You can observe this process by looking at a sample of the same mineral under both natural and polarized light. If the mineral appears the same under both types of light then it has been polished properly. However, if it looks different under each type of light then it must be re-polished.
You should avoid polishing specimens too thin because air bubbles will form between the specimen and the glass slide causing the piece to break when pressed down with a tool. Thicker specimens can be polished without breaking.
Some minerals are fluorescent under ultraviolet light.
The specimen, also known as a slide, is the thing under examination. The majority of the specimens are put on slides, which are flat rectangles of thin glass. A specimen is placed on the glass, and then a cover slip is placed over it. This makes it simple to insert and remove the slide from the microscope.
A few years ago, people used to use cotton swabs instead of coverslips. This is not recommended because bacteria can grow inside the swab and cause infection.
There are two types of microscopes: brightfield and darkfield. In brightfield microscopy, the light that reaches the specimen passes through it and is refracted (bent) by the tissue structure. This creates a picture of the anatomy underneath the surface layer. In darkfield microscopy, only part of the light that reaches the specimen is refracted. The rest goes into another channel of the camera and provides information about the morphology of particles in the sample. Darkfield microscopy is more useful for viewing cells under the surface layer of tissues because normal light would hide them.
Specimens on slides can be stained with dyes that make certain structures stand out in different colors. For example, a red dye will highlight blood cells, while a green dye will show bacteria under magnification. Staining is usually done as part of the preparation process before putting the sample on the microscope; however, stains may be applied to living cells under the microscope using fluorescence-based techniques.
A specimen must be thin enough to allow light from the light source to travel through it. Specimens are occasionally dyed to make them simpler to recognize and discover. A study of blood cells is an example of how this method can help identify diseases.
Thin specimens allow you to see clear details of their structure under the microscope. This is particularly important for looking at very small organisms or cellular detail. Thin specimens are also useful when trying to replicate results in your own laboratory because you can usually get better pictures that way!
Thin specimens are usually prepared by cutting them into very thin slices with a knife on a glass slide or using a microtome to slice them into very thin sections. The knife should be new and clean without any oils on it because these will leave a film on the sample which will interfere with the microscopy image.
Thin specimens can also be frozen and then thawed out. This makes certain structures within the cell wall expand or break down, revealing color changes or other features we can use to diagnose problems or find markers for diseases.
Finally, thin specimens can be examined with special stains that make certain components of the cell visible under the microscope. These include Giemsa stain for blood cells and methylene blue stain for bacteria.
The wet mount is the most basic method of preparation, in which the specimen is put on the slide in a drop of liquid. After adding the liquid to the slide, a coverslip is put on top, and the specimen is ready for observation under the microscope. The cover slip should be clean and dry before use.
A semisolid or solid form of material that can be molded into various shapes for microscopic examination. These include cell cultures, tissue sections, and mineral specimens. The three main types are paraffin wax, resin, and frozen section media.
Material prepared for light microscopy studies that retains its shape when placed on a glass slide or other support material. Includes preparations for fluorescence, reflection, and electron microscopy.
Preparation of samples for transmission electron microscopy (TEM). A thin slice of sample material is fixed to a mesh screen using a chemical fixative. The sample slice is then washed in water to remove any residual chemical reagent and stained with a solution containing heavy metals at appropriate concentrations for viewing under the TEM.
Under the microscope, samples look like tiny maps showing us the location and distribution of elements within the tissue. Scientists use this information to understand how tissues work and what roles each element plays in creating these structures.