Introduction to hemocytometry
It is a technique used to enumerate the total cell count in the blood or other biological body fluids. This can be done either by using a haemocytometer or by an electronic cell counter.
In certain pathological conditions, the value of the different types of cells may vary.
Thus, by counting the cells in the blood or body fluids, it can be found out if an individual is normal or not
Broadly, the cell count is done mainly:
To find out normal and abnormal count of the cells
To support and confirm clinical diagnosis of the patient
To find out the response of the patient to the treatment
PRINCIPLE OF CELL COUNTING
The blood is diluted with appropriate known volume of diluting fluid and then counting is
done by using haemocytometer.
This is an instrument used for counting the cells in blood or fluid.
It consists of a special instrument called counting chamber, cover glass, pipette for diluting the blood rubber tube with plastic mouth piece for drawing blood or fluid in pipette.
1. Counting Chamber:
It is a thick glass slide with two identical ruled areas separated by empty space and two elevated ridges on both sides. Either of the ruled areas is used for counting the cells. There are different types of counting chambers viz. old Neubauer counting chamber, improved Neubauer counting chamber, burker
counting chamber and fuch’s rosenthal counting chamber.
Old Neubauer counting chamber:
In this, the central platform is set 0.1 mm below the level of the two sides, which gives the chamber a depth of 0.1mm. The ruling covers an area of 9sq.mm divided into 9 squares of 1 sq. mm. each. The four corner squares are subdivided into 16 squares, each with an area of 1/16 of an sq. mm. the central ruled area of 1 sq. mm. is divided into 16 large squares by a set of triple lines. These large squares are further subdivided into 16 small squares by single lines.
Improved Neubauer counting chamber:
Here, the counting square is of 9 sq. mm area (3mm × 3mm). The four corner squares of the area of 1 sq. mm. each (1mm × 1mm) are used for white blood cell count. In this, the triple lines which divide the central large square are very much closer to each other. The central ruled area is divided into 25 large squares. These squares are subdivided to form 16 smaller squares each with an area of 1/400 of 1 sq. mm. The four corners and one middle subsquare are used for red blood cell count. The depth of the improved Neubauer chamber is the same that is 0.1mm.
Old V/S Improved Neubauer Chamber
The space occupied by the triple lines in the old Neubauer chamber being used to produce extra large squares.
In old neubauer chamber the gap b/w triple lines was very wide and the rectangular space between them look as similar as the squares in which cells are to be counted. This makes the count very difficult and chances of error was very high.
In old neubauer chamber the lines were very dull and sometimes it was very difficult to recognize them
But in improved neubauer chamber these all faults are removed.
By dividing central square in 25 squares the RBC and platelat count has become easy to do.
2. Cover Glass
A special cover glass is used which has a very smooth, flattened surface and even thickness.
Different thickness are: 0.3mm, 0.4mm (most common), 0.5mm.
two sizes are common: 16 × 22 sq.mm and 22 × 23 sq.mm.
3. Diluting pipette
It is a glass tube pipette with a rubber sucking arrangement. The tubular part of the pipette is graduated from 0 to 1 with the division of 0.1 units. The bulb portion can accommodate 100 units of volume graduated from 1 to 101 on both sides of the bulb. The bulb serves as diluting and mixing chamber for blood. The red bead in it aids in mixing and for identification of red cell pipette from white cell pipette.
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शैक्षणिक वर्ष 2022-23 मधील तांत्रिक व्यावसायिक अभ्यासक्रमांना प्रवेशासाठी लागणारी आवश्यक प्रमाणपत्रे
Dr Yellapgrada Subba Rao
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