Q.(a) Describe the method of blood smear preparation. OR

A blood smear is made by spreading a small drop of blood thinly and evenly across a glass slide, then fixing and staining it, so individual blood cells can be examined clearly under a microscope.

Answering part (a): Method of blood smear preparation.

1. Preparation: Use a clean, grease-free glass slide. A small drop of fresh blood (from a finger prick or venous sample) is placed near one end of the slide.

2. Spreading: A second slide (the 'spreader slide') is placed at an angle of about 30-45 degrees in front of the blood drop, drawn backward to touch and spread along the edge of the drop (letting the blood spread evenly along the spreader's edge by capillary action), and then pushed forward smoothly and quickly in one continuous, even motion. This produces a thin, uniform smear that thins out gradually toward the far end (the 'feathered edge'), where cells lie in a single layer, ideal for examination.

3. Drying: The smear is allowed to air-dry completely, protected from dust and flies.

4. Fixing: The dried smear is fixed by flooding it briefly with methanol (or absolute alcohol), which preserves the cell structure and prevents the cells from washing away during staining.

5. Staining: The fixed smear is stained, commonly with Leishman's stain or Giemsa stain (Romanowsky-type stains), which differentially colour the nucleus and cytoplasm of different blood cell types, making them distinguishable.

6. Washing and drying: After the appropriate staining time, the slide is gently washed with buffered water to remove excess stain and allowed to air-dry.

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