This technique provides best quality of specimen for examination.
The fresh specimen is immersed in a liquid called a fixative for several hours (the necessary time depends on the size of the specimen).
The fixative, formalin causes the proteins in the cells to denature and become hard and "fixed." Adequate fixation is probably the most important technical aspect of biopsy processing. The fixed specimen is fixed with paraffin wax.
The next morning histologist removes the paraffin- impregnated specimen and "embeds" it in a larger block of molten paraffin. This is allowed to solidify by chilling and is set in a cutting machine, called a microtome. The histotech uses the microtome to cut thin sections of the paraffin block containing the biopsy specimen.
These delicate sections are floated out on a water bath and picked up on a glass slide.
Paraffin wax is dissolved from the tissue block by using solvents. Then the tissues are stained with dyes - Hematoxylin and eosin.
The stain combination, casually referred to by pathologists as "H and E" yields pink, orange, and blue sections that make it easier for us to distinguish different parts of cells. Typically, the nucleus of cells stains dark blue, while the cytoplasm stains pink or orange.