Anatomy and Physiology I (BIO130) Spring 2010 Prof. AnnMarie Armenti, MS

Exercise 3: The Microscope Care of the Compound Microscope –Hold in an upright position with one hand on the arm and the other supporting the base –Use grit-free lens paper to clean the lenses. Clean all lenses before and after use –Begin focusing on the lowest power objective –Use the coarse adjustment knob only with the lowest power lens –Always use a coverslip with wet mount preparation –Before returning the microscope: Remove the slide from the stage Rotate the lowest-power objective lens into position Replace the dust cover or return it to the storage area

Exercise 3: The Microscope Activity 1: Identifying the Parts of the Microscope Activity 2: Viewing Objects through the Microscope Activity 3: Estimating the Diameter of the Microscope Field Activity 4: Perceiving Depth Activity 5: Preparing and Observing a Wet Mount

Head Rotating Nosepiece (support) (specimen) (precise focusing) (support) (10x) (regulates the light passing through the condenser – contrast) Iris Diaphragm Lever Condenser (Small lens that concentrates The light on the specimen)

Exercise 3: The Microscope Magnification –Interplay of 2 lenses Ocular Lens (10x) – Virtual image that we see Objective Lens (4x, 10x, and 40x) – Real image –Total Magnification: Power of Ocular Lens x the power of Objective Lens –10 x 4 = 40x –Field: the area seen through the microscope

Exercise 3: The Microscope Microscope Field –Size of the microscope field decreases with increasing magnification –Determining the diameter of the field Field diameter = 4mm Object extends across half the field 4 ÷ ½ = 2 mm Remember: Start lowest-power objective to bring the grid lines into focus

Exercise 3: The Microscope Perceiving Depth –Depth of the Field (depth of the specimen clearly in focus) is greater at lower magnification 1. Use Iris diaphragm lever to reduce the light Increase contrast 2. Focus with the coarse adjustment until threads are out of focus 3. Slowly focus them again, note which thread comes first

Exercise 3: The Microscope Preparing a Wet Mount 1. Place a drop of saline in the center of slide 2. Rub the inside lining of your cheek 3. Transfer cheek scrapings into saline on slide 4. Add a tiny drop of iodine or methylene blue 5. Stir 6. Coverslip: prevents soiling of the lens if you misfocus Bottom edge should touch one side of the fluid drop Then carefully lower the coverslip. *** Probably want to dim the light with the iris diaphragm Increase Contrast

How do you Prepare for Next Week? Lecture: –Read Chapter 1 and 2 in the Text –Read over handouts Laboratory: –Finish Lab. Exercise 1 and 3 –Read Lab. Exercises 4 and 5A