MAJ Kris Paolino, MDInfectious Disease Staff

Chief, Clinical Trials CenterWalter Reed Army Institute of Research

Disclaimer

The views expressed in this presentation are those of the speaker and do not reflect

the official policy of the Department of Army, Department of Defense, or U.S.

Government

MicroscopyTechnical field of using

microscopes to view samples and objects that cannot be seen with the unaided eye

We will be using light microscopy

Calculating the magnificationIdentify the magnification of the ocular lensIdentify the magnification of the objective

lens in useMultiply the two together

Example:Ocular lens = 10xObjective lens = 40xMagnification is 400x

Oil Immersion lensesOil immersion is a technique to increase

resolution of a microscope

Use of transparent immersion oils with an oil immersion objective lens

You will need oil to have adequate visualization of the malaria parasites on the high power objectivesThe lens will typically state “oil” on the side

Correct use of a light microscopeMake sure the scope is plugged in and turned on

Ensure you are starting at the LOWEST power objective

Mount your glass slide using the cover slips or slide holder

Adjust the light source using the diaphragmRule of thumb:

Low light intensity for lower magnification High light intensity for higher magnification

Correct use of a light microscopeAdjust the ocular lenses to your eyes as

appropriateTake off your glasses if you wear them

Again, starting at the lowest objective focus using the COARSE adjustment knobsThis is the last time you will use this knobSome would say to move the lens as close to the

slide as possible, and then adjust away

DISCLAIMER: Anyone who breaks a slide will automatically be

enrolled in our next malaria challenge trial

Correct use of a light microscopeFocus in on your target (i.e.

red blood cells) at the LOWEST power

Make sure what you want to look at is CENTERED

In the thin smear of the malaria slide you want to try to start at the “feathered edged” of the slideCells are more spread out

Correct use of a light microscopeFocus in on your slide by switching to the

next highest objective lens (it will “CLICK” into position)

Adjust illumination as necessary

Each time you switch up to the next highest objective, re-focus, and re-center in on the slide using the FINE adjustment knob ONLYi.e. DON’T BREAK THE SLIDE

Correct use of a light microscopeWhen you get to the high power objectives, you

will need to use a drop of immersion oil

For malaria diagnostics, you will use the 100x objective

To place the oil, rotate the objective lenses so they are out of the way, and place a single drop of oil directly on the slide

Slowly rotate the oil lens back over the slide so that the drop of oil touches the lens

Correct use of a light microscopeUsing the oil lens, focus on the slide using

the FINE adjustment knob only until the cells are in focus

When you are done, wipe the oil immersion lens and the slide with lens paper only

If you have a camera (smartphones included) try to take a photo of what you are seeingInclude magnification in the teleconsultation

Keep your scope cleanUSE LENS PAPER TO WIPE THE OCULAR

AND OBJECTIVE LENSES AS NECESSARY

DON’T USE OIL ON LOWER POWER OBJECTIVE LENSES

DON’T TOUCH THE LENSES WITH YOUR FINGERS

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eutrophil

osinophil

Basophile