Diethyl ether fixative solution serves as an effective fixative in in vitro diagnostics. It is characterized by its use in histological, cytological and microscopic examinations. Its function is to preserve cell structures and thus enable detailed examination of tissue samples. Substances contained in the solution, such as ethanol, diethyl ether, acetic acid and formaldehyde, work together to cross-link and stabilize proteins and lipids in the cells. The result is a hardening of cell structures that prepares tissue samples for further examination. Thus, the diethyl ether fixative solution enables precise observation of cell morphology, aids in the identification of disease states, and contributes significantly to the accuracy of diagnostic tests.