{"id":108,"date":"2025-06-17T20:46:42","date_gmt":"2025-06-17T20:46:42","guid":{"rendered":"https:\/\/press.wpunj.edu\/humanbiologylabmanual\/chapter\/__unknown__\/"},"modified":"2025-07-17T11:42:57","modified_gmt":"2025-07-17T11:42:57","slug":"microscopy","status":"publish","type":"chapter","link":"https:\/\/press.wpunj.edu\/humanbiologylabmanual\/chapter\/microscopy\/","title":{"raw":"Microscopy, Cellular Structure & Function, and Body Tissues","rendered":"Microscopy, Cellular Structure & Function, and Body Tissues"},"content":{"raw":"
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Learning Objectives<\/p>\r\n\r\n<\/header>\r\n

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  1. Describe how to handle and care for a compound light microscope.<\/li>\r\n \t
  2. Recognize and give the function of the parts of a compound light microscope.<\/li>\r\n \t
  3. Correctly use a compound light microscope.<\/li>\r\n \t
  4. Identify components of an animal cell on both a diagram and a model.<\/li>\r\n \t
  5. State functions of each cellular component\/structure of an animal cell.<\/li>\r\n \t
  6. Make a wet mount of several sample types.<\/li>\r\n \t
  7. Identify slides of various types of body tissue: epithelium (squamous and ciliated columnar), connective tissue (bone, cartilage, blood), neuron, and skeletal muscle.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n \r\n

    MICROSCOPY<\/h1>\r\n

    As we study the human body, we will learn that the basic unit of life is the cell. Our body consists of over 200 different types of cells, but we cannot see these cells with the naked eye. The smallest object we can view with our eyes is about 0.1 millimeter (mm). Let\u2019s put that into perspective: a single grain of sand is 0.5 mm, and we can see smaller than that! But in order to view anything smaller than 0.1 mm, such as a cell, we need to use the essential tool of the biology lab, a microscope.<\/p>\r\n

    Microscopy has three basic concepts: magnification, resolving power, and contrast. Magnification<\/strong> is the factor by which the image of a specimen is enlarged. Resolving power<\/strong> is the degree to which two adjacent points in a specimen are seen as separate. Contrast<\/strong> is how well details stand out against the background on an image.<\/p>\r\n

    There are various types of microscopes available for use in a laboratory setting. Microscopes can be categorized into light microscopes and electron microscopes based on what is used to produce an image.<\/p>\r\n

    Light microscopes can use visible light to magnify an object through glass lenses, producing two-dimensional images. The most commonly used light microscope is the compound light microscope<\/strong> and is called this because light passes through two lenses. The lens closest to the eye is called the ocular lens, while the lens closest to the object (specimen) is the objective lens. Most compound microscopes have one ocular lens, which magnifies 10x, and 3 or 4 objective lenses of different magnifications, that can interchanged. Depending on the specimen, it is routine to stain the specimen with colored chemicals in order to increase the contrast.<\/p>\r\n

    Electron microscopes focus a beam of electrons within a vacuum column by using electromagnetic lenses, creating a two or three-dimensional image of the surface of an object. (Figure 1.1a and 1.1b for a comparison of micrographs.) The wavelength of electrons is much smaller than the wavelength of visible light, resulting in higher resolution. Electron microscopes also have the capability of higher magnification than light microscopes. (Table 1 for a comparison of light and electron microscopes.) To enhance the image quality, biological specimens, cells or structures, have to be fixed and coated with a conductive metal, such as gold-palladium alloy, to prevent damage by electrical charging of the specimen surface as the electrons bombard it.<\/p>\r\n

    \"image\"<\/p>\r\n

    Figure 1.1a<\/strong> A light micrograph of a blood smear, showing hundreds of red blood cells and two white blood cells.<\/p>\r\n\"\"\r\n

    Figure 1.1b<\/strong> Scanning electron micrograph of red blood cells.<\/p>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
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    Table 1 Comparison between a Compound Light Microscope and Electron Microscope<\/p>\r\n<\/td>\r\n<\/tr>\r\n

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    Compound Light Microscope<\/strong><\/p>\r\n<\/td>\r\n

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    Electron Microscope<\/strong><\/p>\r\n<\/td>\r\n<\/tr>\r\n

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    Glass lenses<\/p>\r\n<\/td>\r\n

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    Electromagnetic lenses<\/p>\r\n<\/td>\r\n<\/tr>\r\n

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    Illumination by visible light<\/p>\r\n<\/td>\r\n

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    Illumination due to a beam of electrons<\/p>\r\n<\/td>\r\n<\/tr>\r\n

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    Lower resolution (\u2248 200 nm)<\/p>\r\n<\/td>\r\n

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    Higher resolution (\u2248 0.1 nm)<\/p>\r\n<\/td>\r\n<\/tr>\r\n

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    Lower magnification (up to 2,000 x)<\/p>\r\n<\/td>\r\n

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    Higher magnification (up to 1,000,000 x)<\/p>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n

    \"image\"<\/p>\r\nFigure 1.2<\/strong> A scale to show relative sizes of cells and their components in relation to the type of microscope needed.\r\n

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    Rules for Microscope Use<\/p>\r\n\r\n<\/header>\r\n

    \r\n\r\nObserve the following rules using a microscope:<\/strong>\r\n
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    1. To carry a microscope to and from your lab bench, grasp the arm with your dominant hand and support the base with the other hand, always keeping the microscope upright.<\/li>\r\n \t
    2. The lowest power objective (4x) should be in position both at the beginning and at the end of microscope use.<\/li>\r\n \t
    3. Use only lens paper for cleaning lenses.<\/li>\r\n \t
    4. Keep the stage clean and dry to prevent rust and corrosion.<\/li>\r\n \t
    5. Do not remove parts of the microscope.<\/li>\r\n \t
    6. Do not use coarse focus when viewing a specimen with the high-power objective. You can break the slide you are viewing.<\/li>\r\n \t
    7. Report any malfunctions.<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n

      STEREOMICROSCOPE (Dissecting Microscope)<\/h3>\r\n

      This instrument has a platform for specimens that can be easily manipulated. It gives a three-dimensional view of a variety of specimens that do not have to be treated (fixed or stained) in advance of their viewing. It is very useful for viewing materials that have to be handled. For instance, if specimens have to be cut open and dissected, the stereomicroscope permits easy access to the stage, and a variety of magnifications. It can be used on living organisms (like fruit flies, parts of plants, animal organs, and other specimens).<\/p>\r\n\r\n

      COMPOUND LIGHT MICROSCOPE<\/h3>\r\n

      The compound light microscope uses two sets of lenses and light to view an object. This microscope is used to examine small or thinly sliced sections of objects under higher magnification than would be possible with the stereomicroscope. With this type of microscope the specimens typically have to be mounted on a microscope slide. If the material is very small or thin, it is possible to make a wet mount and look directly at the sample. Otherwise, it is necessary to prepare the specimen by slicing it very thin, fixing it with chemical preservatives, and staining the specimen with colored dyes that bind to different parts of the cell structure. One example is methylene blue, which chemically binds to DNA and colors that material inside the cell (usually changing the colors of the nucleus and chromosomes.)<\/p>\r\n

      Note to student<\/em>s<\/em>:<\/em><\/span> Write all data and answers to questions on the Lab Report provided.<\/p>\r\n\r\n

      Activity 1: Identifying Microscope Parts<\/em><\/h6>\r\n

      Obtain a compound light microscope from the microscope cabinet, carrying it properly, and place it securely on the lab bench. Label the light microscope, using the text that follows.<\/p>\r\n

      \"\"\r\nFigure 1.3<\/strong> Compound light microscope with binocular head and mechanical stage. Label the light microscope using the terms from the following list by recording on the Lab Report.<\/p>\r\n\r\n

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      1. Eyepieces (ocular lenses)<\/strong>: Ocular lenses generally have 10x magnification. A microscope may have one (monocular) or two (binocular) ocular lenses.<\/li>\r\n \t
      2. Body tube<\/strong>: Holds nosepiece at one end and eyepiece at the other end; conducts light rays to your eyes.<\/li>\r\n \t
      3. Arm<\/strong>: Supports upper parts and provides carrying handle.<\/li>\r\n \t
      4. Nosepiece<\/strong>: Revolving device that holds objective lenses.<\/li>\r\n \t
      5. Objectives (objective lenses):<\/strong><\/strong>\r\n