FORMALDEHYDE (FORMALIN) 4.0 %, 1000 mL

PRINCIPLE

Tissue fi xation is mainly done by the immersion of the tissues into chemical agents (fi xatives) in order to interrupt the degradation processes that occur after the cell death, and thus, it preserves the structures and composition of the tissue. Fixing agents have the ability to stop the enzyme activity, the process of tissue autolysis and protein denaturation. Some fi xatives can be used, likewise, as a preservative, but not in all cases can be ensured a long term preservation. Fixation is not synonymous with tissue preservation. Fixation types: The fi xation processes can be classifi ed in two kinds depending on the results obtained in regards the tissue structure and its biochemical composition.

1. Histological fi xation: it basically preserves the tissue structures, regardless if it produces or not biochemical changes.

2. Histochemical fi xation: it’s intended to preserve the maximum possible the molecular composition.