Used primarily in the field of histology and pathology for tissue fixation. The combination of paraformaldehyde and glutaraldehyde in a bicarbonate buffer creates a potent fixative that preserves cellular structures with minimal distortion. This mixture is particularly effective for electron microscopy, ensuring fine ultrastructural details are retained. It is also employed in immunocytochemistry to maintain antigenicity, allowing for accurate detection of proteins and other cellular components. Additionally, it is utilized in the preparation of samples for in situ hybridization, where it helps preserve nucleic acids while maintaining tissue integrity.