Inverted Microscope- Definition, Principle, Parts, Labeled Diagram, Uses, Worksheet
Microscopes are instruments that allow us to see objects that are too small to be seen by the naked eye. They use different types of light sources and lenses to magnify the image of the specimen and make it visible on a screen or an eyepiece. There are many types of microscopes, such as compound microscopes, stereo microscopes, electron microscopes, and inverted microscopes. Each type has its own advantages and disadvantages, depending on the purpose and the nature of the specimen.
In this article, we will focus on inverted microscopes, which are a special type of light microscopes that have their components arranged in a reverse order compared to conventional microscopes. Inverted microscopes have the light source and the condenser lens above the specimen stage, while the objective lenses and the nosepiece are below the stage. This allows them to view specimens that are in large containers or culture vessels, such as Petri dishes, flasks, or tubes. Inverted microscopes are widely used in cell biology, microbiology, biotechnology, and other fields that require observing living cells or tissues in their natural environment.
In the following sections, we will explain the definition and history of inverted microscopes, their working principle, their main parts, their uses, their advantages and limitations, and some of the companies that manufacture them. We will also provide a free worksheet and answer key for you to test your knowledge and understanding of inverted microscopes. By the end of this article, you will have a comprehensive overview of what inverted microscopes are and how they work. Let`s get started!
An inverted microscope is a type of light microscope that has its optical components arranged in a reverse order compared to a conventional upright microscope. In an inverted microscope, the light source and the condenser are located above the specimen stage, while the objective lenses and the nosepiece are below the stage. This allows the user to view specimens from below, rather than from above.
The inverted microscope was invented in 1850 by J. Lawrence Smith, a professor of chemistry and natural history at the Medical College of Louisiana (now Tulane University). Smith was interested in studying the crystallization of minerals and metals under high temperatures and pressures. He devised a way to place a small furnace on the stage of a microscope and observe the changes in the specimens from below. He published his invention in the American Journal of Science and Arts in 1852.
Smith`s inverted microscope was mainly used for mineralogy and metallurgy research until the early 20th century, when it was adapted for biological applications. In 1913, Robert Chambers, a zoologist at Columbia University, modified an inverted microscope to study living cells in culture. He used a heated stage to maintain the temperature of the cells and a mirror to reflect light from below. He also added a camera lucida to draw the images of the cells.
In 1924, Paul Weiss, a pioneer of tissue culture and neurobiology at the University of Chicago, improved Chambers` inverted microscope by adding a water immersion condenser and a binocular eyepiece. He also devised a method to grow cells on thin glass coverslips that could be placed on the stage of the microscope. He used his inverted microscope to study the growth and differentiation of nerve cells.
In 1943, Earl Sutherland Jr., a Nobel laureate in physiology or medicine, developed an inverted phase contrast microscope to study hormone action on isolated tissues. He used a special condenser that produced annular rings of light around the specimens, enhancing their contrast and visibility. He also used a rotating stage to change the orientation of the specimens.
Since then, inverted microscopes have become widely used in various fields of biology, especially cell biology, microbiology, immunology, and developmental biology. They are also used for industrial applications such as quality control, inspection, and failure analysis. Modern inverted microscopes are equipped with various features such as fluorescence illumination, digital cameras, image analysis software, and automated stages.
The inverted microscope works on the same principle as the upright microscope, which is to use light rays to form an image of a specimen that can be magnified by the objective lenses. However, the inverted microscope has a different arrangement of its components, which allows it to view specimens in large containers such as Petri dishes and flasks.
The main difference between the inverted and upright microscope is the position of the light source, the condenser lens, and the objective lenses. In the inverted microscope, the light source and the condenser lens are located above the specimen stage, pointing downwards, while the objective lenses are located below the stage, pointing upwards. This is the opposite of the upright microscope, where the light source and the condenser lens are below the stage and the objective lenses are above the stage.
The light source in the inverted microscope can be either a halogen lamp or a LED lamp, which provides illumination for the specimen. The condenser lens above the stage concentrates the light on the specimen and controls the amount of light that reaches the objective lenses. The specimen is placed on a large stage that can hold various types of containers such as Petri dishes, flasks, slides, or well plates. The objective lenses below the stage collect the light that passes through or reflects from the specimen and magnify it to form an image. The image is then sent to the eyepieces or a camera for observation or recording.
The inverted microscope can also use different types of illumination techniques such as brightfield, darkfield, phase contrast, differential interference contrast (DIC), fluorescence, or confocal microscopy. These techniques enhance the contrast and resolution of the image by using filters, polarizers, prisms, or lasers to manipulate the light that interacts with the specimen. Depending on the technique used, different types of specimens can be observed with different levels of detail and clarity.
The inverted microscope is especially useful for viewing living cells and tissues in their natural environment without disturbing them. It can also be used to observe specimens that are too large or thick for conventional slides or coverslips. The inverted microscope has many applications in biology, medicine, biotechnology, microbiology, and materials science.
An inverted microscope has similar components to those of a conventional upright microscope, but they are arranged in an inverted order. The main parts of an inverted microscope are:
- Light source: This is the device that provides illumination for the specimen. It can be a halogen lamp, a LED lamp, or a laser. The light source is located above the stage and points downwards.
- Condenser: This is a lens system that concentrates the light from the light source onto the specimen. The condenser can be adjusted to control the amount and angle of light that reaches the specimen. The condenser is also located above the stage and points downwards.
- Stage: This is the platform that holds the specimen. It can be a fixed stage or a movable stage. A fixed stage is large and flat and can accommodate large vessels such as Petri dishes or flasks. A movable stage can be moved in horizontal and vertical directions to scan different areas of the specimen. The stage is located below the light source and the condenser.
- Objective lenses: These are lenses that collect and magnify the light that passes through the specimen. They are mounted on a rotating nosepiece that allows changing the magnification power. The objective lenses are located below the stage and point upwards.
- Eyepieces: These are lenses that further magnify and focus the image formed by the objective lenses. They are attached to a binocular or a monocular tube that connects to the nosepiece. The eyepieces are located above the objective lenses and point upwards.
- Camera: This is an optional device that can be attached to the eyepiece tube or the nosepiece to capture digital images or videos of the specimen. The camera can be connected to a computer or a monitor for display and analysis.
- Fluorescence attachment: This is an optional device that can be added to the inverted microscope to enable fluorescence microscopy. It consists of a filter cube that contains an excitation filter, a dichroic mirror, and an emission filter. The filter cube selects specific wavelengths of light for exciting and detecting fluorescent molecules in the specimen.
The following diagram shows the parts of an inverted microscope:
|Objective lenses||Movable stage|
The inverted microscope is widely used in various fields of science and industry, especially for observing living cells and tissues in culture. Some of the common uses of the inverted microscope are:
- Cell biology and microbiology: The inverted microscope allows researchers to monitor the growth, morphology, behavior, and interactions of cells and microorganisms in their natural environment, such as in flasks, dishes, or wells. The inverted microscope can also be used to perform live-cell imaging, fluorescence microscopy, time-lapse microscopy, and other techniques that require high-resolution and contrast.
- Tissue engineering and regenerative medicine: The inverted microscope is an essential tool for creating and studying artificial tissues and organs, such as skin, cartilage, bone, blood vessels, and nerve cells. The inverted microscope enables scientists to observe the structure, function, and biocompatibility of these engineered tissues and organs in vitro and in vivo.
- Cancer research and drug discovery: The inverted microscope is used to investigate the mechanisms of cancer development, progression, and metastasis, as well as to screen for potential anti-cancer drugs and therapies. The inverted microscope can also be used to study the effects of drugs on normal and cancerous cells in culture, such as their viability, proliferation, apoptosis, migration, invasion, and angiogenesis.
- Embryology and developmental biology: The inverted microscope is used to study the early stages of animal and plant development, such as fertilization, cleavage, gastrulation, organogenesis, and differentiation. The inverted microscope can also be used to manipulate embryos and stem cells using techniques such as microinjection, electroporation, gene editing, and cloning.
- Material science and nanotechnology: The inverted microscope is used to characterize the properties and applications of various materials and nanomaterials, such as polymers, metals, ceramics, composites, quantum dots, carbon nanotubes, graphene, and nanoparticles. The inverted microscope can also be used to fabricate and manipulate nanostructures using methods such as lithography, self-assembly, scanning probe microscopy, and optical tweezers.
These are some of the main uses of the inverted microscope in different domains of science and industry. However, there are many more applications that can benefit from the advantages of the inverted microscope over the conventional upright microscope.
The inverted microscope has several advantages over the conventional upright microscope, especially for observing living cells and tissues. Some of the advantages are:
- The inverted microscope has a large and fixed stage that can accommodate large vessels such as Petri dishes, flasks, and multi-well plates. This allows the observation of cells and tissues in their natural environment, without the need to transfer them to glass slides or coverslips. This reduces the risk of damaging or altering the specimens during preparation and handling.
- The inverted microscope can also observe cells and tissues in large volumes of culture medium, which provides better nourishment and oxygenation for the specimens. This enables the study of long-term processes such as cell growth, differentiation, migration, and interaction. The upright microscope, on the other hand, can only observe specimens in thin layers of medium on glass slides, which may limit their viability and functionality.
- The inverted microscope can access the cells and tissues from both the top and bottom sections of the culture vessel, as most cells tend to settle at the bottom due to gravity. This allows the examination of different aspects of the specimens, such as morphology, motility, and fluorescence. The upright microscope can only access the specimens from the top section, which may obscure some features or details.
- The inverted microscope prevents the contamination of the specimens by avoiding contact with the objective lens, which may carry dust or microbes from previous observations. This maintains the sterility and integrity of the specimens, which is crucial for biological research and applications. The upright microscope may cause contamination by touching the specimens with the objective lens, especially when using high magnification or oil immersion.
- The inverted microscope can be easily equipped with additional accessories and attachments, such as cameras, fluorescent illuminators, scanners, and micro-manipulators. These enhance the versatility and functionality of the inverted microscope for various purposes and techniques, such as imaging, analysis, measurement, and manipulation. The upright microscope may have limited space and compatibility for adding extra devices or components.
These are some of the advantages of the inverted microscope that make it a valuable tool for studying living cells and tissues in their natural environment. The inverted microscope offers unique capabilities and flexibility that are not easily achievable with the conventional upright microscope.
Despite its many advantages, the inverted microscope also has some limitations that may affect its performance and usability. Some of these limitations are:
- Cost: The inverted microscope is generally more expensive than the upright microscope, as it requires more complex and precise optical components and mechanisms. The cost of acquiring and maintaining an inverted microscope may be prohibitive for some laboratories or institutions.
- Availability: The inverted microscope is not widely available in the market, as it is manufactured by very few companies. This may limit the access and choice of potential users, as well as the availability of spare parts and technical support.
- Optical quality: The inverted microscope may have lower optical quality than the upright microscope, as it has to view the specimens through thick glass vessels such as Petri dishes or flasks. This may introduce distortions, aberrations, or reflections that may affect the clarity and resolution of the images. The inverted microscope also requires very high-quality objectives and condensers to achieve optimal magnification and illumination.
- Working distance: The inverted microscope has a shorter working distance than the upright microscope, as the objectives are located below the stage and closer to the specimens. This may limit the types and sizes of specimens that can be observed, as well as the possibility of manipulating or adding reagents to them during observation. The shorter working distance may also increase the risk of damaging the objectives or the specimens by accidental contact.
These are some of the limitations of the inverted microscope that users should be aware of before deciding to use it for their applications. However, these limitations may be overcome or minimized by using appropriate techniques, accessories, or modifications that can enhance the performance and functionality of the inverted microscope. For example, using thinner glass vessels, using phase contrast or differential interference contrast (DIC) microscopy, using long working distance objectives, or using motorized stages or focus controls. Therefore, users should weigh the pros and cons of using an inverted microscope according to their specific needs and preferences.
Because of the difficulty and the cost of manufacturing the inverted microscope, very few companies are known to produce and sell them. Some of the companies that offer high-quality inverted microscopes for various applications are:
- Zeiss: Zeiss is a German company that specializes in optics and optoelectronics. It has a range of inverted microscopes for research, clinical, and industrial purposes.
- Olympus: Olympus is a Japanese company that produces optical and digital products for various fields. It has a series of inverted microscopes for life science research.
- Nikon: Nikon is another Japanese company that is well-known for its cameras and lenses. It also has a line of inverted microscopes for biological and industrial applications.
- Kruss Germany: Kruss Germany is a German company that focuses on surface science and interfacial chemistry. It offers inverted microscopes for measuring contact angles and surface tension of liquids and solids.
- echoLAB: echoLAB is an Italian company that provides laboratory equipment and solutions. It has a range of inverted microscopes for fluorescence microscopy and cell culture analysis.
- Metkon Technology: Metkon Technology is a Turkish company that specializes in metallography and material testing equipment. It has a series of inverted microscopes for metallographic examination and analysis.
- Horiba Scientific: Horiba Scientific is a French company that offers analytical instruments and solutions for various fields. It has a line of inverted microscopes for Raman spectroscopy and imaging.
These are some of the companies that manufacture inverted microscopes for different purposes and needs. You can visit their websites to learn more about their products and features.
To test your understanding of the inverted microscope, you can download this free worksheet and answer key. The worksheet contains 10 multiple-choice questions that cover the definition, principle, parts, uses, advantages and limitations of the inverted microscope. You can use the worksheet as a self-assessment tool or as a study guide for your exams. The answer key provides the correct answers and explanations for each question. You can check your answers and learn from your mistakes.
To download the worksheet and answer key, click on the links below:
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