Practical hematology Assist.Prof. Dr.Sajeda Al-Chalabi
*RBC COUNTHEMOCYTOMETER
Hemo: blood Cyto: cell Meter: measurement/counter Thus, it is an instrument used to count the blood cells.*
It includes:Neubauer’s slideCover slipRBC pipetteWBC pipette *
NEUBAUER’S SLIDE It is the name given to a thick glass slide. In the centre of the slide, there is an H- shaped groove. On the two sides of the central horizontal bar, there are scales for counting the blood cells. The depth of the scales is 1/10mm or 0.1mm. *Neubauer Hemocytometer
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Hemocytometer Chamber
*The central square is subdivided into twenty five smaller squares and each of these smaller squares is further subdivided into sixteen smallest squares. These are meant for platelet and RBC counting.
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the RBCs are counted in five small squares, four of corners and one of center. (total of 80 smallest squares)
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Cell Counts by Hemocytometer
*COUNTING RULE
Do not count cells touching Bottom line Right line Count cells touching the upper& left lines This is to avoid double counting.*
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DILUTION FACTORS For RBC counting Blood is filled till mark 0.5 and Hayem’s fluid is then filled till mark 101.Both are thoroughly mixed and then few drops are discarded which contain just the diluting fluid in the stem. Thus, 1 portion out of 101 is discarded. So, 0.5 part of blood is in 100 parts of fluid or,1 part of blood is mixed in 200 parts of fluidThus, dilution factor for RBC counting is 200. *
CALCULATION
*HAYEM'S SOLUTION
Hayem's solution contains: sodium chloride 0.5%, sodium sulphate 2.5% and mercuric chloride 0.25%. The sodium chloride to prevent hemolyses, the sodium sulphate discourages clumping of the erythrocytes and the mercuric chloride is a preservation*
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FOCUSING
4X to see the general formation of slide. 10X for WBC counting 40X for RBC counting*
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