Human Blood smear to observe different cells

Human Blood Smear to observe different cells

We take a Microscope, glass slides, spirit lamp, sterilized lancet, a drop of blood, Giemsa stain, and Distilled water.

Preparation of Blood Smear

1. Obtain 2 clean microscope slides, alcohol wipes & lancet.
2. Clean a finger with an alcohol & puncture lancet.
3. Place a small drop of blood at the end of the one side.
4. Use another slide to make a thin blood film as per the instructions below.

1. Place the second slide at a 45° angle & touch the slide with a blood drop.
2. Move the spreader slide to touch the drop of blood allowing the drop to spread by capillary action along the edge of the slide.
3. Immediately pull/push the slide away from the blood droplet, making a thin smear that dries quickly as you move away from the droplet.
4. A perfect smear will have a ‘feathered’ edge & separated RBCs when you view it with the microscope.

● Staining the blood smear(Horizontal Staining procedure).

1. Place a thoroughly dried smear on the horizontal staining rock.
2. Flood smear with fixative for 10 seconds drain.
3. Flood smear with fixatives for 10 seconds drain.
4. Rinse the smear with DW for 1 minute.
5. Air dry & examine under the microscope, using low power 1st then high power.
6. Observe as many different types of blood cells as possible, and pay close attention to size, frequency & nuclear features.

Observation:- Different types of blood cells are visible. (Neutrophils, Basophils, eosinophils & monocytes).

● Erythrocytes[RBCs]:- They are the most numerous blood cells i.e. about 4-6 millions/mm3 They are also called RBCs. In man & in all mammals. Erythrocytes are devoid of nucleus & biconcave in shape. In the other vertebrates, they have a nucleus. The red cells are rich in haemoglobin a protein able to bind oxygen. Hence, these cells are responsible for providing oxygen to tissue & partly for recovering CO2 produced as waste. In the mammalian RBC, the lack of a nucleus allows more shape for the HB & biconcave shape of these cells to raise the surface & cytoplasmic volume ratios.

● Leucocytes[WBCs]:- They are responsible for the defense of the blood 5000-7000/mm3

They are of 2 types =

        (1)Granulocytes     & 

        (2)Agranulocyte/Lymphoid cells.

    The term granulocytes is due to the presence of granules in the cytoplasm of the cells. These granules have a different affinity towards neutral, acidic, or basic stains & give the cytoplasm different colors. So granulocytes are neutrophils, eosinophils, to basophils. Agranulocytes are distinguished into the lymphocytes and monocytes.

Neutrophils:- 50 to 70% They are very active in phagocytic bacteria & are present in large amounts in the pus of wounds. The nucleus is multilobed. 

Eosinophils:- 2 to 4% usually bilobed nucleus coarse & strongly oxyphils granules. These cells attack parasites & phagocytes antigen-antibody complex.

Basophils:- (5 to 10%) Nucleus usually bilobed coarse basophils granules in the cytoplasm. They secrete anti-coagulant & vasodilatory substances such as histamine & serotonin.

Lymphocytes:- (20 to 40%) They are large with round nucleus & basophilic cytoplasm. They are the main constituents of the immune system which is a defense against the attack of pathogenic micro-organisms. such as viruses, bacteria, fungi & Protista.

Monocytes:- (3 to 8%) are large with a kidney-shaped nucleus, and slightly basophils.Thrombocytes/Platelets:- The main function of platelets/Thrombocytes is to stop the loss of blood from wounds(clotting). For this, they aggregated & released factor which promotes the blood coagulation. Among them, there is the serotonin which reduces the diameter of cup vessels & slows down the blood flow, and the fibrin which raps the cells from the clotting.