Which component is typically involved in the fixation process?

Formaldehyde is a commonly used fixative in histopathology due to its ability to effectively preserve tissue structures and cellular details. It works by cross-linking proteins, which helps maintain the morphological integrity of the tissues during processing and staining. The cross-linking action is crucial because it stabilizes cellular components, preventing autolysis and decay, thus allowing for accurate diagnosis under the microscope.

While other substances, such as ethyl alcohol and xylene, play important roles in different stages of tissue processing—ethyl alcohol in dehydration and xylene in clearing—formaldehyde is specifically recognized for its effectiveness in fixation. Water is not suitable as a primary fixative due to its tendency to cause tissue swelling and distortion, making formaldehyde the definitive choice for fixation in histopathology. Its widespread use is also supported by its ability to preserve nucleic acids and antigens, which is essential for subsequent analyses like immunohistochemistry.