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Practical work #14. Calculation of thrombocytes quantity in blood
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Practical work #14. Calculation of thrombocytes quantity in blood

There are direct and indirect methods of counting thrombocytes. To conduct the last one, they use definition of quantity of blood platelets in the tinted smear. This index correlates with the quantity of erythrocytes and in blood analysis is written as 1:1000. After this, absolute quantity of thrombocytes is calculated in 1 l of blood. Direct method is more accurate. Examination is performed in Goryaev’s camera immediately after taking the blood. To stabilize the blood, the following solutions can be used: 5-7% trilone B, 1% ammonium oxalate with methylene-blue and others. Calculation methods are also different: using phase-contrast and luminescent microscopy.

Objectives: to calculate and estimate the quantity of thrombocytes in the examined blood.

Requirements for work: microscope, lighter, mixer for the red blood, Goryaev’s camera, covering glass, holder with test-tube, Petri dish with wet filtrating paper (wet camera). 1% solution of ammonium oxalate, needle, 96% ethanol, 2% alcohol solution of iodine, cotton wool.

Principle for calculation of thrombocytes is similar to the one which is used for the definition of erythrocytes amount. But thrombocytes are degrading fast if we were to retire them from the bloodstream, that’s why the blood should be taken as fast as possible and the mixer should be wet. So, mixer should be partially filled with stabilizing liquid from the test-tube. Prick the finger with the needle and put the ending of the mixer into the blood, fill it till the mark 0,5. Check for abcence of air in the end of the mixer, so stabilizing liquid will not drop on the blood on finger. So, mixer should be held horizontally. Fill the mixer with blood, put the ending of the mixer into the test-tube with liquid and fill it till the mark 101. Mix the content of the melanger and leave it in the horizontal position for 10 minutes for haemolysis of erythrocytes to occur. Prepare the calculating camera. Fill it with solution from melanger and put in Petri dish for 5 minutes. It is necessary for the thrombocytes to settle on the bottom. Than take it out of the wet camera, pur under the microscope and calculate thrombocytes in 25 large quadrates of the net (25 • 16 = 400 small quadrates).

Recommendation for writing down the results:

Number of thrombocytes in 1 mkl is calculated by the following formula:

X = (a • 400 • 200) / 400

Where x – the quantity of thrombocytes in 1 mkl;

a – the quantity of thrombocytes in 400 small quadrates;

200 – degree of blood dilution;

400 – multiplier, which turns the result to the volume of 1 mkl (from the volume of small quadrate).

Practically the amount of thrombocytes in 400 small quadrates is multiplied by 2000 and then again by 106 and we have the amount of thrombocytes in 1 l.

Answer following questions in conclusion:

Is the quantity of thrombocytes normal in the examined blood?



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