Formalin solution in phosphate buffer is widely used in histopathology and cytology for tissue fixation. It helps preserve cellular structures by cross-linking proteins, ensuring minimal distortion during microscopic examination. This solution is essential in preparing tissue samples for diagnostic purposes, such as identifying diseases or abnormalities. It is also employed in research laboratories to study cellular morphology and tissue architecture. Additionally, it serves as a stabilizing agent in vaccine production, ensuring the integrity of antigens. Its buffered nature maintains a stable pH, enhancing its effectiveness in preserving biological specimens.