How Are Histology Slides Prepared? Step by Step Guide

How Are Histology Slides Prepared? Step

by Step Guide You may have prepared a slide in your biology classes at some point in your high school life. If you are involved in biological research, you must have been pro in submitting tissue specimens to a histology lab. A histology lab is prepared excellent histopathology slides – each containing thin sections of specimens for microscopic evaluation.

However, have you ever wondered how histology technicians do this? Here we tell you.

Tissue fixation Slide preparation starts with fixation of the tissue specimen. It is the first step, and its purpose is to prevent tissue autolysis. For best results, biological tissues samples are transferred to a

fixative just after collection. There are many types of fixative available. However, most specimens are fixed in 10% neutral buffered formalin.

Specimen transfer After fixation, specimens are trimmed using a micro cutter or scalpel so that they fit into the appropriate tissue cassette. Specimens should not be too large and fit perfectly on the cassette.

So, they are trimmed not to touch the edges. Additionally, they should not be too thick, or they can waffle.

Tissue processing Tissue processing is done using a paraffin block in three steps: Dehydration – It involves immersing specimen in high alcohol concentration to remove water and formalin from the tissue.

Clearing – An organic solvent like xylene is used to remove alcohol allowing infiltration with paraffin wax.

Embedding – It is the final step where specimens are infiltrated using paraffin wax. The tissue surrounded by a large block of molten paraffin wax creates a block which when solidifies provides support matrix allowing thin sectioning.

Sectioning Specimens are now ready to be cut into sections that can be placed on a slide. Wax is removed from the surface to expose the tissue. A microtome is used to cut extremely thin tissue section.

Once cut, the tissue is carefully transferred to a warm bath where they are made to float on the surface. Charged slices are best for this process as they improve tissue adhesion to glass and reduce the chance of sections washing off.

Staining Most cells are transparent and can’t be seen unless stained. Histochemical stains are particularly used to provide contrast to tissue sections making the structure more visible.

Staining makes the evaluation of tissue possible. Following staining, a coverslip is mounted on tissue specimen on the slide for the protection.

Your slide is ready for speculation.