Biolab 1

• The eyepiece or ocular is the lens through which theobject or the specimen is viewed. This lens usually magnifies theimage passing through it by 10 times. It also has a pointer whichmay be used to pinpoint the object or part of an object beingviewed.
• The revolving nosepiece holds four objective lenses.Grasp the nosepiece and note that it may be rotated, bringingeach objective lens into place. Feel the distinctive "click" as eachobjective is in proper position for viewing.
• The objective lens gives the initial magnification. The microscope may have four of these, located on the revolving nosepiece, enumerated below. In general, the lower the magnification, the shorter is the objective lens and the farther it is positioned from the specimen when focused.
• The scanning objective is the shortest objective which magnifies the size of an object 4 times. It has the broadest field of view of all the lenses and is used for initial focusing of objects
• The low-power objective (LPO) magnifies by 10 times
• The high-power objective (HPO) magnifies by 40 times. It is much longer than the first two.
• The longest objective is the one with 100x magnification. This is the oil immersion objective (OIO)
• The stage is the flat surface with a round opening or aperture in the center. The slide or the specimen to be viewed is positioned on the stage over the aperture. The stage may be equipped with a mechanical device into which the slide is clipped. This so-called mechanical stage allows the movement of the slide to be manipulated by means of two knobs located underneath the stage. Other microscopes do not have a mechanical stage and instead, stage clips are used to fasten the slides on the stage
• The substage condenser is a lens located under the stage aperture, and its distance from the stage is controlled by a knob. Its function is to concentrate the light from the source and focus it on the specimen
• The iris diaphragm is beneath the condenser and functions to control the amount of light passing through the specimen. This can be manipulated to affect a change in light intensity
• The substage illuminator is the source of light which illuminates the object being viewed. This may be replaced by a mirror
• The illuminator control knob is usually located on the side of the base i.e., the part that supports the entire microscope. Also found just below the mechanical stage adjustment knobs, it controls the light output of the illuminator.
• The adjustment knobs are located on both sides of the microscope, just above the base. There are two of these, usually with one smaller and located just outside the other
• The coarse adjustment knob is the bigger of the two. Its function is to focus when using the scanning and low-power objectives
• The fine adjustment knob is used in focusing at the high-power and oil-immersion objectives.
• Magnification. The compound light microscope combines the magnifying power of the eyepiece with that of the objective lens. The magnifying power is etched on the housing of each lens. Simply multiply the magnification values of the objective in place and the eyepiece to see how many times the specimen is enlarged.
• Resolving Power. This is a measure of lens quality. Quality lenses have high resolving power, the ability to deliver a clear image in fine detail. If the magnification of the lens is high, but the resolution is low, it is of little value. Although such an image would be enlarged, it would not be clear enough to show details. Resolution is also affected by the cleanliness of the lens. It is a good practice to clean the lenses with lens paper before and after every use
• Field of View. This is the size of the area that the lens views. The higher the magnifying power of an objective lens, the smaller the area viewed. When one switches to a lens with higher magnification, the central portion of what was visible under low power is seen further enlarged. It is important to center the specimen before increasing magnification, to prevent one from losing sight of the specimen
• A feature of a good microscope is its parfocal capability. This means that when a specimen is in focus under low-power magnification, one can switch to high-power magnification and have the specimen remain in fairly good focus. Usually, a slightadjustment with the fine adjustment knob is all that is required for a sharp image
• The study of cells constitutes the science of cytology
• Two basic types of cell: prokaryotic and eukaryotic
• Three parts seen in a slide under a compound light microscope: cell membrane, nucleus, and cytoplasm
• Muscle Tissue: Spindle-shaped or Fusiform
• Frog's Ovary: Spherical-shaped
• Frog's Blood Smear: Oval shape
• Frog's Blood Smear (White Blood Cells): Amorphous shape
• Frog's Testis: Whip-like flagellum