RBC count: For this we need hemocytometer which contains neubauer chamber. RBCs can be seen at 40 X while WBCs can be seen at 10X, while chamber can be seen at 4 X. Drop of RBCs is placed at the chamber at 45º angle. While counting follow the LLL(leave left lower) and RRU(read right upper). Apparatus: Hemocytometer, pipette, diluting fluid and cover slip, RBC pipette.  Procedure: Erythrocyte count is the number of RBCs in one micron liter of a given blood sample. It is done by the following procedure;? Take hemocytometer which contain newbar chamber, RBC pipette, WBC pipette. RBC pipette is marked by 0.5?1 on its stem and above bulb it is marked by 101. RBC pipette is also known as  R.Thoma erythrocyte counting pipette.? Suck the blood up to mark 0.5; take care that blood column in the capillary is free from air bubbles.? Remove pipette and dip in the diluting fluid and suck diluting fluid steadily up to mark 101. ? After this pipette is removed from the diluting solution and is rotated gently so that diluting solution is mix with blood horizontally. Grip pipette between thumb and finger by its bulb ends and rotate well it for about one minute; here dilution is of 200 times.? Now hold the pipette at an angle of 45 degree to the surface of counting chamber and its point is applied narrow slip between chamber and cover slip. Care should be taken so that there are no air bubbles under the cover slip. If there is over flowing of fluid in the grooves of counting chamber then the cover slip and chamber is removed, cleaned and the whole process is repeated.? For RBC counting there are 25 large squares in the chamber and each large square has 16 small squares. For counting leave left upper and read right lower. For counting in 25 large squares Right, left uppers and lowers and central square is counted.                                                          RBCs can be calculated as under; Length of one larger square; 1mm                                Area = 1/5 × 1/5 = 1/25mm2                                      Area of small square = 1/25 × 1/16= 1/400 mm2Area of one small square = 1/400 mm2 Volume of small square = 1/400 × 1/10 = 1/4000 mm3 No of RBCs in 80 small squares = X No of RBCs in 1 small sq. = X/80 No of RBCs in 1/4000 small sq. = X/80 × 4000 × 200             Here 200 is the dilution factor…         After simplification; No of RBCs in 80 small sq. = X × 10000 ………millions RBCs Diluting solutions may be 0.9 % NaCl solutions, normal saline, Tisson fluid and Ganti fluid etc.  Properties of diluting fluid:? It should not hemolyse the corpuscles? It should promote the even distribution? It should not cause precipitation of protein and other substances in blood which will interfere the counting of cells? It should not act as a fixative so that cells retain their original shapeIt should be able to inhibit the growth of bacteria and other moulds growthWhite Blood cell Count (WBC count):                   4- 1-11-12 WBC parameters are TLC (total leukocyte count) with Neubauer chamber, DLC (differential leukocyte count) in this blood smear is made.Procedure: Follow the technique described for erythrocyte count except diluting pipette; in this use the pipette with white bead (WBC counting pipette). Draw the blood up to point 0.5 mark. Draw dilution fluid up to mark 11 and dilution will be 1 ratio 20. Discard 2-3 drops from pipette before filling the chamber; wait for 1-2 minutes for the lysis of RBCs and settling of cells. Count cells under 10 X in large four corners of the square and apply formulae for calculation. Cells in 64 squares = X Cells in one square = X/64 Cells in 1/160 squares = X/64 × 160 × 20 No of WB cells = X × 50 …………….. Thousand/ mm3