fixeeroplossing

Fixeeroplossing is a chemical solution used in biology, medicine, and histology to preserve biological tissue or cells by fixation. Fixation aims to stabilize the sample’s structure, halt enzymatic activity, and prevent autolysis and decomposition, thereby maintaining morphology for microscopic analysis.

The most common fixeeroplossing is aqueous formaldehyde, often used as buffered formalin (about 4% formaldehyde in phosphate buffer). Other widely used fixatives include paraformaldehyde, glutaraldehyde, Bouin’s solution, Carnoy’s solution, and alcohol-based fixatives. The choice depends on the downstream technique; for example, aldehyde fixatives create cross-links between proteins, which preserves architecture well but can mask antigenic sites, affecting immunohistochemistry. Alcohol-based fixatives preserve nucleic acids better and are sometimes preferred for molecular analyses, though they may cause tissue shrinkage or hardening.

Procedural considerations include promptly submerging the specimen, using adequate fixative volume (typically at least 10:1 fixative to tissue), and fixing for a duration appropriate to the tissue size and fixative. After fixation, samples are washed, dehydrated, and prepared for embedding, sectioning, and staining. In electron microscopy, stronger fixatives like glutaraldehyde are common, often followed by osmium tetroxide.

Safety and handling are important: many fixers, especially formaldehyde and picric acid-containing solutions, are toxic and potentially carcinogenic. Use in a fume hood with appropriate personal protective equipment, and follow local regulations for storage and disposal. Storage conditions and shelf life vary by fixative and concentration.