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3.3: Using the Dissecting Microscope - Biology

3.3: Using the Dissecting Microscope - Biology


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A dissecting microscope is a useful tool for viewing small features or fine details. This type of microscope uses what is called incident lighting, where the light is shone onto the specimen (rather than through it, as you will see later).

View a specimen from today’s lab under the dissecting microscope. Position your lighting so that it creates as few shadows as possible, then look through the ocular lenses. You will have two knobs on the side of the microscope. One of these is a coarse focus that determines your overall magnification. Use this knob to decide on how closely you’d like to view features of your specimen. You’ll notice that it gets quite blurry very quickly. Once you have the magnification you want, use the fine focus to resolve the image (de-blur it).

Draw an interesting feature from your specimen below.


How to Select a Microscope

Click on any of the following links to find out more!

      magnify the tiny detail and structure of plant cells, bone marrow and blood cells, single-celled creatures like amoebas, and much more. Almost every homeschool family or hobbyist will need a 400x compound microscope to study cells and tiny organisms in biology and life science. are low-power microscopes designed for observing whole objects like flower pollen and rock crystals with a 3D view.

    We offer compound and stereo homeschool microscopes that work especially well for homeschool families’ budgets and needs!

        will enhance both group and individual microscope studies by enabling magnified images to be saved and shared on the computer.
        allow students and hobbyists to take their microscopic adventures anywhere!

      Difference Between Compound Microscope and Dissecting Microscope

      The main difference between Compound Microscope and Dissecting Microscope is that Compound Microscope is the microscope that is used to observe small objects with high magnification power, whereas Dissecting Microscope is used to dissect the specimen.

      Compound Microscope Vs. Dissecting Microscope

      We use a different type of tools in biology such as microscopes. They are very helpful to observe microorganisms and pathogens etc. that cannot be seen by the naked eye. There are different types of this device according to their structure and function and are used for a specific purpose. Two such types are the compound microscope and the dissecting microscope. A compound microscope is a microscope that is used to observe the magnified images of small specimens is known as a compound microscope, on the other side, the dissecting microscope is the microscope that is used to examine and dissect the specimen. So, compound microscopes are made to look through a specimen whereas dissecting microscopes are designed for viewing the surface features of a specimen and for dissecting the small insects, etc. Both these types of the microscope are used to magnify an object by focusing light through lenses and prisms towards a specimen. The light may act directly, or it may be reflected in nature, so that it may illuminate the object. The light is transmitted through the object in case of a compound microscope on the flip side in a dissecting microscope, the object is viewed by the help of reflected light. The light source is present below the specimen in case of compound microscope whereas the light source is above the specimen in case of dissecting microscope. A compound microscope has multiple objective lenses and one eyepiece while a dissecting microscope has a single objective lens and two eyepiece lenses. A compound microscope has high magnification power up to 1000X on the other hand, the dissecting microscope has a low magnification power of up to 70x.

      Comparison Chart

      Compound MicroscopeDissecting Microscope
      A microscope that is used to observe the magnified images of small specimens is known as a compound microscopeA microscope that is used to examine and dissect the specimen is known as dissecting microscope.
      Other Names
      It is also known as a light microscope.It is also known as a stereomicroscope.
      Light Source
      A light source is present below the specimen in case of a compound microscope.The light source is present above the specimen in case of a dissecting microscope.
      Illumination of Object
      An object is observed through transmitted light in a compound microscope.In a dissecting microscope, the object is viewed by the help of reflected light.
      Magnification Power
      A compound microscope has high magnification power up to 1000X.A dissecting microscope has a low magnification power of up to 70x.
      Resolution Power
      A compound microscope has high-resolution power.A dissecting microscope has low-resolution power.
      Working Distance
      It has a shorter working distance of 4mm.It has a longer working distance of 150mm.
      Preparation of specimen
      The specimen is specially prepared through staining etc. to observe under a compound microscope.There is no preparation required to observe an object under a dissecting microscope.
      Number of Lenses
      A compound microscope has multiple objective lenses and one eyepiece.A dissecting microscope has a single objective lens and two eyepiece lenses.
      Function
      The compound microscope is used to observe minute and smaller things, like protozoa, bacteria, and cells, etc.It is used to study the surface of the specimen, in microsurgeries, for studying dissections, in watch and small circuit boards making, etc.

      What is a Compound Microscope?

      A Compound Microscope is the one that uses several objective lenses with different magnification powers to view specimens. It uses light to observe the specimen. Thus specimen should be thin enough for light to pass through it. Staining is also required to observe different sections of a specimen under a compound microscope. It has a magnification power of 400X to about 1,000X and shows detailed features of specimens. It has a shorter working distance of 4mm.

      What is Dissecting Microscope?

      A Dissecting Microscope is also known as a stereomicroscope. It has a lower magnification power of 70x. A beam of light is projected above the specimen. This type of microscope is used to view larger specimens and to dissect small objects such as insects etc. It has a longer working distance of 150mm.

      Key Differences

      1. A microscope that is used to observe the magnified images of small specimens is known as a compound microscope whereas a type of microscope that is used to examine and dissect the specimen is known as dissecting microscope.
      2. A compound microscope is also called as a light microscope while dissecting microscope is also known as a stereomicroscope.
      3. An object is observed through transmitted light in a compound microscope on the other hand, in a dissecting microscope, the object is viewed by the help of reflected light.
      4. The light source is present below the specimen in case of a compound microscope. Conversely, the light source is present above the specimen in case of a dissecting microscope.
      5. A compound microscope has multiple objective lenses and one eyepiece on the flip side, a dissecting microscope has a single objective lens and two eyepiece lenses.
      6. The specimen is specially prepared through staining etc. to observe under a compound microscope while there is no preparation required to observe an object under a dissecting microscope.
      7. A compound microscope has a high magnification power of up to 1000X on the other side, a dissecting microscope has a low magnification power of up to 70x.
      8. A compound microscope has a shorter working distance of 4mm whereas dissecting microscope has a longer working distance of 150mm.
      9. A compound microscope has high-resolution power while a dissecting microscope has low-resolution power.
      10. The compound microscope is used to observe minute and smaller things, like protozoa, bacteria, and cells, etc. on the flip side, a dissecting microscope is used to study the surface of a specimen, in microsurgeries, for studying dissections, in watch and small circuit boards making, etc.

      Comparison Video

      Conclusion

      Above discussion summarizes that the compound microscope is used to observe the small objects with high magnification power and resolution while dissecting microscope is a microscope with low magnification power and resolution and used to dissect small objects.

      Janet White

      Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White


      Parts of Dissecting Microscope | Botany

      It is the basal, horse-shoe shaped or circular part of dissecting microscope. It is made of heavy material. It provides support to other parts of microscope.

      It is short but strong, hollow cylindrical rod. Its one end is fixed at the foot or base. It provides support to the mirror, adjustment screw and other parts.

      It is short and movable rod that fits into the hollow tube of the stand. With the help of the adjustment screw, this limb can be moved up and down.

      It is a horizontal arm. Its one end is attached with the vertical limb and on it’s another end is attached lens. Folded arm is movable. It can be moved up and down as well as left and right.

      It is a simple convex lens of either 2X, 3X, 5X, 10X or 20X magnification.

      It is rectangular glass plate attached to the upper end of the stand or limb. Slide or the object, to be observed, is kept on the stage.

      Two clips are fitted on the stage. They are used to hold the slide in the desired position.

      This is a screw used to adjust or move the vertical limb up and down.

      It is concave reflecting mirror attached to the lower inner side of the stand. Light rays are reflected or focussed on the stage by the mirror.

      Place the slide or the object, to be observed, on the stage. Bring the lens over the slide with the help of folded arm. Put the clips on two ends of the slide to keep it in position. Move the vertical limb up and down by adjustment screw to bring the slide into desired focus. Adjust the light over the slide with the help of the mirror and observe.

      In case some material is to be dissected, place the material over the slide, repeat the entire process mentioned above, dissect the material with the help of needles or other instruments, and observe.


      Compound Microscope vs Dissecting Microscope

      Structure

      A dissecting microscope has two lens arrays which are aligned in such a manner that they bring about a three dimensional magnification of the object. It usually has two eyepieces for this same reason. The compound type uses multiple lenses to collect light, and its lenses help to focus the light to the eye of the viewer. Due to the presence of these multiple lenses, these are not only large and heavier but they are also more expensive when compared the dissecting variant.

      Light for Viewing

      In all microscopes, the object that is magnified is viewed with the help of light. In some cases, this light may act directly to illuminate the object, or it may be reflected in nature, so that the object gets illuminated via the reflections. The light on the basis of which the object present on the glass slide is viewed is one of the differentiating points. In a dissecting or stereo microscope, the object is viewed with the help of reflected light rather than transmitted light, whereas in the compound type, the light is transmitted through the object itself. The main reason why reflected light is preferred in a dissecting microscope is that this kind of light allows a person to view an object that would either be too thick in its sectioning and/or too opaque, due to which it will not allow light to pass through.

      Function

      The resolution of the dissecting microscope is much lower than that of the compound variant, and hence, the former is used to study the surface of solid substances, studying dissections, in microsurgeries, for watch making, and in the making of small circuit boards. The compound variant is used to view far more minute and smaller things, like bacteria, protozoa, cells, etc.

      These magical devices have come a long way since their invention centuries ago, and now we have complex versions of these devices, like the electron microscope, which provides an even greater level of magnification. You can read more about the different types of this device here.

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      Dissecting Microscope Definition

        • Dissecting microscope also known as stereo or stereoscopic microscope. It is an optical microscope that is designed for low magnification observation of a specimen.
        • It uses the reflected light rays from the specimen surface instead of transmitted light rays.
        • It provides low power magnification as compared to compound microscopes.
        • The magnification power of a Dissecting microscope ranges from 5x-80x.
        • It produces a three-dimensional image of the specimen rather than a flat image.
        • Dissecting microscope contains two separate objective lens and eyepiece, which creates two separate optical paths for each eye. As a result, it creates a 3D image of the specimen.

        Interference microscopes

        Although all optical microscopes in the strict sense create images by diffraction, interference microscopy creates images using the difference between an interfering beam unmodified by the specimen and an otherwise identical beam that illuminates it. A beam splitter divides light into two paths, one of which passes through the specimen while the other bypasses it. When the two beams are combined, the resulting interference between them reveals the structure of the specimen. The first successful system, invented by British microscopist Francis Smith and French physicist Maurice Françon in 1947, used quartz lenses to produce reference and image-forming beams that were perpendicularly polarized. Although this worked well for continuous specimens, in the case of particulates it was better to have the reference beam pass through a bare area of the specimen preparation, and by 1950 the use of half-silvered surfaces and slightly tapering slides allowed polarized light to be dispensed with.

        Meanwhile, differential interference contrast (DIC) was developed by Polish-born French physicist Georges Nomarski in 1952. A beam-splitting Wollaston prism emits two beams of polarized light that are plane-polarized at right angles to each other and that slightly diverge. The rays are focused in the back plane of the objective, where they pass through a composite prism that is isotropic at the midpoint, with an increasing optical path difference away from the midpoint. The background colour of the image depends on the setting of the prism, which can be slid longitudinally to produce a spectrum of colours that vary through the spectrum to black. The sensitivity is greatest in the middle position, but the colour contrast is greatest when a strong background tint is selected. More-recent developments include asymmetrical illumination contrast and modulation contrast, which exploit offset or oblique illumination.


        1. NO FOOD, BEVERAGES, GUM, in the labs. Cell phone usage is also prohibited in the lab.
        2. Conduct yourself in a responsible manner at all times in the lab. Horseplay, pranks and practical jokes are prohibited and will not be tolerated. If you participate in inappropriate behavior the INSTRUCTOR HAS THE RIGHT TO ASK YOU TO LEAVE THE lab.
        3. Students cannot be in the lab without an instructor present.
        4. Read all lab procedures, precautions, and equipment instructions thoroughly before each lab. Follow all written and verbal instructions carefully. Perform only those experiments authorized by the instructor. If during the lab you don’t understand, stop and ask the instructor before proceeding. Never do anything in the lab that is outside of your instructors directions or that is not in your lab procedure.
        5. Do not begin lab activities touch any chemicals or equipment until you are instructed to do so.
        6. Work areas should be kept organized and clean at all times. Only necessary items (lab notebook, worksheets, etc.) should be on your workbench. Backpacks and purses must be stored under the benches or against the walls. CLEAN ALL OF YOUR WORK SURFACES AND EQUIPMENT AT THE END OF THE EXPERIMENT. Safely dispose of waste in its proper container and place glassware in the grey bins by the sink. DO NOT STACK GLASSWARE. If the bin is full ask the instructor for another bin.
        7. Keep aisles clear. Push lab stools under the lab benches when not in use.
        8. Know where the safety equipment is and how to use it. This includes the first aid kit, eyewash station, safety shower, fire extinguisher, and fire blanket. Know the location of the fire alarm, and emergency phone. In the event of a fire drill during lab time containers must be closed, gas valves off, fume hood, and all electrical equipment must be turned off.
        9. NEVER DISPOSE OF ANYTHING IN THE SINK. All materials are to be disposed of in the proper hazardous waste containers with the assistance of the instructor. All waste containers must be closed and placed inside a secondary containment bin.
        10. As classes in these labs use toxic chemicals, keep your hands away from your face, eyes and mouth while working in the lab. Always wash your hands thoroughly with warm water and soap before leaving the lab to prevent injury or illness. This is part of proper lab procedure.
        11. Students are not permitted in the prep room areas (between the lab rooms).
        12. Handle all living organisms used for lab experiments in a respectful, humane manner.
        13. Microscopes must be properly cleaned, the electrical cords properly wrapped, and returned to their places with their protective covers.

        Disposal of all hazardous waste is ONLY to be handled by the instructor and in a manner consistent with federal, state and local hazardous waste disposal regulations. Organic solvents are never to be disposed of down the sink receptacles will be provided as needed for their collection. All hazardous chemical substances must be placed in the appropriate type of container and labeled with chemical, name and date, sealed and placed upright in a gray plastic bin.


        3.3: Using the Dissecting Microscope - Biology

        These brand new resources support the use of practicals across various A-level biology specifications (OCR, AQA and Edexcel).

        • Tested materials to support Common Practical Assessment Criteria key practicals
        • Support materials for teachers, technicians and students
        • Student revision materials to help revise for indirect examination of practicals

        This new resource supports the use of practicals across various A-level biology 2015 specifications for England (OCR, AQA, Edexcel and Eduqas).

        This experiment allows students to go from the plant on the desk, to observing a stained specimen under the microscope in less than 4 minutes (as shown in the images above). The viewed specimen clearly shows the location of vascular bundles and the xylem, phloem and sclerenchyma or collenchyma.

        The use of the stain toluidine blue provides a colour difference between lignified and non-lignified cell walls, clearly highlighting specialised cells and one adaptation they have.

        This experiment provides a quick and eye-catching way to teach about the vascular tissue in plants and the structure of plant stems. It provides students with the opportunity to develop (and demonstrate) their scientific drawing skills as well as their use of a light microscope and eye-piece graticule.

        • Tested materials to support the A-level practical endorsement (CPAC)
        • Support materials for teachers and technicians
        • Student worksheet to help provide evidence for meeting the practical skills requirements
        • Student revision materials to help prepare for exams

        Support materials for other key practicals in A-level specifications can be found on the A-level set practicals main page.


        Parts of a Compound Microscope

        Before exploring the parts of a compound microscope, you should probably understand that the compound light microscope is more complicated than just a microscope with more than one lens.

        First, the purpose of a microscope is to magnify a small object or to magnify the fine details of a larger object in order to examine minute specimens that cannot be seen by the naked eye.

        Here are the important compound microscope parts.

        Eyepiece: The lens the viewer looks through to see the specimen. The eyepiece usually contains a 10X or 15X power lens.

        Diopter Adjustment: Useful as a means to change focus on one eyepiece so as to correct for any difference in vision between your two eyes.

        Body tube (Head): The body tube connects the eyepiece to the objective lenses.

        Arm: The arm connects the body tube to the base of the microscope.

        Coarse adjustment: Brings the specimen into general focus.

        Fine adjustment: Fine tunes the focus and increases the detail of the specimen.

        Nosepiece: A rotating turret that houses the objective lenses. The viewer spins the nosepiece to select different objective lenses.

        Objective lenses: One of the most important parts of a compound microscope, as they are the lenses closest to the specimen.

        A standard microscope has three, four, or five objective lenses that range in power from 4X to 100X. When focusing the microscope, be careful that the objective lens doesn’t touch the slide, as it could break the slide and destroy the specimen.

        Specimen or slide: The specimen is the object being examined. Most specimens are mounted on slides, flat rectangles of thin glass.

        The specimen is placed on the glass and a cover slip is placed over the specimen. This allows the slide to be easily inserted or removed from the microscope. It also allows the specimen to be labeled, transported, and stored without damage.

        Stage: The flat platform where the slide is placed.

        Stage clips: Metal clips that hold the slide in place.

        Stage height adjustment (Stage Control): These knobs move the stage left and right or up and down.

        Aperture: The hole in the middle of the stage that allows light from the illuminator to reach the specimen.

        On/off switch: This switch on the base of the microscope turns the illuminator off and on.

        Illumination: The light source for a microscope. Older microscopes used mirrors to reflect light from an external source up through the bottom of the stage however, most microscopes now use a low-voltage bulb.

        Iris diaphragm: Adjusts the amount of light that reaches the specimen.

        Condenser: Gathers and focuses light from the illuminator onto the specimen being viewed.

        Base: The base supports the microscope and it’s where illuminator is located.

        How Does a Compound Microscope Work?

        All of the parts of a microscope work together - The light from the illuminator passes through the aperture, through the slide, and through the objective lens, where the image of the specimen is magnified.

        The then magnified image continues up through the body tube of the microscope to the eyepiece, which further magnifies the image the viewer then sees.

        Learning to use and adjust your compound microscope is the next important step.

        It's also imperative to know and understand the best practices of cleaning your microscope .

        The parts of a compound microscope work together in hospitals and in forensic labs, for scientists and students, bacteriologists and biologists so that they may view bacteria, plant and animal cells and tissues, and various microorganisms the world over.

        Compound microscopes have furthered medical research, helped to solve crimes, and they have repeatedly proven invaluable in unlocking the secrets of the microscopic world.


        The Classroom Flow: Comparing and Contrasting Microscope Types

        1. Start out by announcing that today will be the intoduction to a multi-day cell lab where students will have the chance to work with microscopes and view and create their own slides.

        2. Review the cell theory (see powerpoint slide# 2) to get students oriented to today's work.

        • Note: I always like to remind students that before every big shift in science thinking typically comes a technology breakthrough and that cell biology is no different--as microscopes improved, so did out ability to see, compare, and understand the organelles and processes happening inside cells.

        3. Take out the two types of microscopes from the microscope cabinet: a compound light microscope and a dissecting microscope. Ask students to share out some differences they see between the two using a casual popcorn protocol.

        4. Once you have gotten to the most basic differences (number of oculars, size and number of objectives, the location of the stage), you can begin to talk about the purpose for using each one. I typically describe dissecting microscopes as similar to binoculars and give examples as to when we would use them: to look at fruit fly eye color or wing shape, to see our skin/fingerprints, all macro/surface type examples and then contrast that to the compound light microscope we will be using: inside cells, inside hair protein, etc.

        5. Once you have discussed the two types of light microscopes, introduce the concept of electron microscopes. Use the powerpoint slide show to demonstrate examples of what they look like (slide #5) and compare/contrast them to light microscopes specifically in these areas (slide #3-4):

        Preparation needed in order to view specimen

        Reasons for choosing one type (light vs. electron) over another

        Transmission vs. scanning electron microscopes

        6. After you have discussed the differences and pros/cons, show students various pictures of organisms and ask them if they have been produced by a transmission or an electron microscope (slide #6, 10, 12, 16, 19).