Vävnadsberedning

Vävnadsberedning, often translated as tissue processing, is a crucial step in the preparation of biological tissue samples for microscopic examination. This process involves a series of chemical and physical treatments designed to preserve the tissue's structure, render it suitable for sectioning, and enhance its visibility under a microscope. The primary goal is to fix the tissue, removing water and replacing it with a medium that solidifies and provides support, allowing for thin slices to be cut.

The initial step in vävnadsberedning is fixation, where the tissue is immersed in a fixative solution. Formalin is a commonly used fixative, which cross-links proteins, preventing autolysis (self-digestion) and putrefaction (bacterial decomposition). Following fixation, the tissue undergoes dehydration, typically by passing it through a series of increasing concentrations of alcohol. This removes all water from the tissue.

After dehydration, the tissue is cleared, usually with a solvent like xylene, which is miscible with both alcohol and the embedding medium. This step removes the alcohol and prepares the tissue for infiltration. The cleared tissue is then infiltrated with an embedding medium, most commonly paraffin wax. The molten wax permeates the tissue, filling all the spaces previously occupied by water.

Once infiltrated, the tissue is embedded in a block of paraffin wax, which is allowed to solidify. This solid block provides the necessary support for cutting thin sections using a microtome. The resulting thin sections can then be mounted on microscope slides, stained to highlight specific cellular components, and examined under a microscope for diagnostic or research purposes. Other embedding media, such as resin, may be used for specialized applications requiring thinner sections or better preservation of certain cellular structures.