MANUAL PHYSIOLOGY PRACTICAL - Repository:The Medical ...

FM/UOJ
Keep the cells under focus (by constant adjustment of the knob because the
slightest alteration in the depth can affect the image) and move the slide about and study
the structure of various types of cells and their size in relation to red cells. The red cells
can be easily identified because they are pink non- nucleated discs found all over the
field. You have to search for the white cells which will be seen as distinct cells with
nucleus stained purple with clear or granulated cytoplasm. Remember that the cells are
spheres and at any time the microscope will be focused only in one plane of the cell.
Therefore, it will be necessary to adjust the focus up and down to see the cell in full.
Identification of leucocytes
Note the following points with regard to any leucocyte.
a. The size and shape of the nucleus.
b. Presence or absence of cytoplasmic granules.
c. When present the size, number and staining reaction of the granules.
If the nucleus occupies only a small portion of the cell and if it is lobulated, the
cell is a polymorpho-nuclear leucocyte. If there are three more clear lobes then the cell
may be Neutrophil; if the lobes are clearly defined and arranged like spectacles then it is
probably an eosinophil; but if the two lobes lie on top of each other because of the
position of the cell, then only one small lobe can be seen. The nucleus of the basophil is
enlongated and poorly divided into three lobes.
If the nucleus is not lobulated but spherical and fills almost all the cell then the
cell is a lymphocyte. I the cell has a large kidney shaped nucleus, it is a monocyte; the
nucleus of the monocyte can appear circular or even oval shaped depending on the
orientation of the cell on the slide.
If cytoplasm is clear and light purplish in color, the cell is an agranulocyte. If
there is only scanty cytoplasm then the cell is a lymphocyte can be found is sizes equal to
red cells (small lymphocytes) or much larger than the red cells (large lymphocyte). If
the cells more than double the size of the red cell and lots of clear cytoplasm then the cell
is a monocyte. If the cytoplasm is not clear but no definite granules can be seen and the
nucleus is lobulated, the cell is a neutrophil. If the granules are bluish, large and
discrete, then it is a basophil. If the granules are reddish and just distinguishable as
discrete granules then it is eosinophil. The number of granules in an eosinophil is more
than in a basophil.
The first and important part of the practical is to observe the different leucocyte
under the microscope and gain experience in identifying them. If you see any cell then
make sure that you identify it correctly by showing it to a teacher. When you come
across a rare cell like monocyte, eosinophil or basophil, show it to others also. If you
could not see one in your slide go around and see these cells in some others microscope.
It is important that you become familiar with the appearance of all leukocytes before
proceeding to the next part of the practical.
Blood
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