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?
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.