Cells and Microscopy

∞ generated and posted on 2020.12.19 ∞

Compound microscopes are the traditional means of viewing the microscopic world, especially the world of cells.

The goals in viewing the presented videos is to gain an appreciation of cells and their parts (cell biology) as well as to be introduced to the use along with avoidance of misuse of compound microscopes.

As this lab is on both cell biology and microscopy, the above is a great video on the origin and to some degree the microscopic diversity of cellular life, with great visuals. Though a bit old, © 1981, it is surprisingly accurate and takes a refreshingly phenotypic rather than genotypic perspective on life's diversity.

The above video provides great computer animations of what goes on inside of eukaryotic cells.

The above video is a fun summary of what a eukaryotic cell is all about. Though it starts off a bit dry, it improves!

The above video provides a description of how to do the various wet mounts that we will be doing and as derived from this video. Note the consistent emphasis on making sure that what is being viewed is very thin!

The above video provides a nice introduction to how to use a compound microscope in the laboratory. For instance, your highest magnification objective lens may be 100× rather than 40×. Note that a few details will differ between different types of microscopes but mostly the presented ideas are consistent from microscopes to microscopes.

The following will start us off towards introducing the compound microscope:

The following are some tips on how to get the most out of your microscopy:

Make sure the microscope is plugged in and turned on.
Start with the mechanical stage (and thereby focus) set to the highest position.
Make sure that the condenser is in the all the way up position.
Make sure the iris diaphragm is almost completely closed (but not completely).
Make sure that your slide is actually in the clip. Not on top of the clip, not beneath the clip, not some crazy angle relative to the clip, but in the clip.
Make sure that you move the slide around using the knobs associated with the mechanical stage (don't manually move slides around unless of course you don't have a mechanical stage).
Make sure that you use the focus knobs to try to focus in on the specimen, starting with the coarse focus knob and then using the fine focus knob to finish the job.
Start focusing using the lowest magnification objective lens. Typically you will have to move the objective lens closer to rather than farther away from the specimen when you start to focus (since people often move the objective lenses away from a specimen when they are done with it). This won't always be the case, however.
If you switch to a higher magnification objective lens, you may need to adjust the focus a bit. This is because you reduce the depth of field when going from lower to higher magnification plus your optics may not be perfect. What was cleanly in focus thus will not necessarily remain in focus but nonetheless should be close to being in focus.
Most modern microscopes are binocular, possessing two eye pieces (known as ocular lenses) and it should be possible to adjust the interpupillary distance between these eyepieces so that you can observe the specimen using two eyes (the proper way to use a binocular microscope) rather than using just one eye.
If the light is too intense for your eyes, try closing the iris diaphragm further before instead directly reducing the light intensity via the illuminator (though feel free to do that too if you find that they light is too bright for your eyes—generally it is a good idea to start with light at its highest intensity and then step down that intensity if need be).
Lastly, dirty optics are not pleasant to look through.

Focusing in on a Human Pancreas slide.

Focusing in on a Euglena slide.

Focusing in on a Thyroid and Parathyroid slide. Note that at a little after 2:30 I say "atomic nuclei" when I should have said "cell nuclei". Oops…