Post on 07-Aug-2015
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- 1. Microscope Dr. Imran Yunus
- 2. Who is this? Any guesses?
- 3. TOPIC MICROSCOPE
- 4. By now you know that my voice is tragically out of order. So I cant shout as I used to. So just read this, When I lost my voice, I gained my words; In chasing our dream, we get resurrected.
- 5. OBJECT: To study the different parts of a compound microscope.
- 6. Lets discuss the formation of a compound microscope; what are the different parts of a compound microscope?
- 7. OCULAR LENS OR EYEPIECE: It is usually a set of convex lens and field lens present in a short cylinder, which fits the top and at the body tubes.
- 8. BODY TUBE: It is a long metallic cylinder with an eye piece at the upper end and screw at the lower end. It can be moved vertically by coarse adjustment screws.
- 9. NOSE PIECE: It is a circular flat screwed attached to the body tube which holds two or more objective lenses of different magnitudes. It can be rotated to bring the required objective lens against the eyepiece.
- 10. OBJECTIVE LENS: There is usually a single lens present in a metallic cylindrical case with engraved magnitudes.
- 11. Low powered & high powered objective The low powered objective lens magnifies the image 10 times as compared to the normal eye, it provides the maximum field for viewing. The high powered objective lens magnifies the image 40 times.
- 12. COARSE ADJUSTMENT SCREWS There are two wheels one on either side mounted on a spiral tooth axle. They move the body tube against stage in vertical direction to achieve focus.
- 13. FINE ADJUSTMENT SCREW: These are two smaller knobs below the coarse adjustments screws. They provide sharp focus.
- 14. STAGE It is a horizontal plate with a central hole below the body tube either fixed or movable against the objective lens. It is used to place glass slides having a specimen to observe.
- 15. STAGE CLIPS: They are two flat metallic clips placed in the clip holes. They hold the specimen during observation.
- 16. CONDENSER It is a moveable or fixed lens mounted below the stage. It converges the light source on the object
- 17. IRIS DIAPHRAGM: it is assembly of semi lunar metallic plate which regulates; i.e. increase or decrease the intensity of reflected light by diameter of its aperture.
- 18. MIRROR OR LIGHT SOURCE. It is a Plano-concave mirror fixed in a movable holder. It reflect right upwards towards the stage.
- 19. ARM OF THE MAIN BODY. It is a solid structure on which different parts of the microscope are mounted and is used to grip the microscope.
- 20. INCLINED JOINTS: It is a joint where the main body is attached to the pillar of foot or base. It keeps the microscope at various inclination angles to facilitate the viewing.
- 21. FOOT OR BASE: It is the lower solid part of the instrument on which it rests and it is horse-shoe shaped.
- 22. so lets try something new ! No one must feel awkward if a question is thrown at them and they fail to answer !
- 23. Identify different parts of microscope!
- 24. What is this back ground picture? Any guesses?
- 25. Experiment no 7B HEMOCYTOMETER
- 26. OBJECT: To study the Hemocytometer.
- 27. HEMOCYTOMETER GRID: RED SQUARE = area: 1X1= 1 mm2, volume: 100 nl. GREEN SQUARE = area: 0.25X0.25= 0.0625 mm2, volume: 6.25 nl. YELLOW SQUARE = area: 0.20X0.20= 0.04 mm2, volume: 4 nl. BLUE SQUARE = area: 0.05X0.05= 0.0025 mm2, volume: 0.25 nl. DEPTH: 0.1 mm.
- 28. REQUIREMENT: Hemocytometer (improved neubauers chamber) and microscope.
- 29. PROCEDURE: Improved neubauers chamber is a heavy colorless glass slide which has two vertical grooves in the central area. The central platform in between the two vertical grooves is divided into two equal halves by a transverses grove
- 30. Top view Lateral view NEUBAURS SLIDE Modified from image taken from wikipedia.com
- 31. PROCEDURE: A square is marked on each half so that two preparation may be set up simultaneously for observation. Each of these squares has got the counting chamber and a size of 3mm X 3mm i.e. an area of 9mm2 Each square is divided into nine smaller squares with a dimension of 1mmx 1mm having an area of 1mm2 .
- 32. How are the counting platforms divided?
- 33. PROCEDURE: Examining the counting chamber under the microscope we find that the four smaller squares at the corners of counting are divided into sixteen smaller squares each. Each of these sixteen smaller squares has an area of 1/4X1/4 mm. i.e. an area of 1/16mm2 The corner squares are used for white blood cell count.
- 34. How are the four smaller squares at the corners of counting chamber divided? For what purpose do we use the corner counting chambers?
- 35. PROCEDURE: Examine the central square under high power of microscope. This square is divided into 25 medium squares each of the size 1/5mmX1/5mm thus having a surface area of 1/25mm2. These medium squares are bounded by thick lines and each is further sub-divided into sixteen smaller squares.
- 36. While examining the central platform of the counting chamber what do we find?
- 37. PROCEDURE: These smaller squares therefore are 1/20mmX1/20mm in size having an area of 1/400mm2. These squares are used for red blood cell count. Generally the four squares at the corners and the fifth at the center are used
- 38. What is the area of the smaller squares of the RBC counting area?
- 39. PROCEDURE: Height of the central platform having the counting chamber is 0.1mm less than the ridges on either side. When a cover slip is placed over the central platform and fluid containing cells is examined under it, thickness of the film is 0.1mm or 1/10mm
- 40. Height of the central platform having the counting chamber is _______mm less than the ridges on either side?
- 41. Calculation For RBC Count 1 small square = 1/10 x 1/25 x 1/16 = 1/4000 mm3
- 42. Calculation for WBC Count: 1 squares = L X B X D = 1mm X 1mm X 1/10 = 1/10 mm3
- 43. PRECAUTION While in use the counting chamber should be absolutely clean. To observe the smaller squares under high power, use low power first and then shift to high power.
- 44. PRECAUTION Lenses of the microscope should be kept spotlessly clean using a soft cloth. Never use the coarse adjustment of the microscope while viewing under high power as the chamber might be crushed.
- 45. Precautions? Who wants to give it a shot?
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