Testicular tissue fixative， also known as FSA fixative， is a fixative made by mixing sucrose， acetic acid， and formalin (an aqueous solution of formaldehyde) in a certain proportion. Formaldehyde， as a representative aldehyde fixative， has extremely strong permeability and good fixation effect; Sucrose and acetic acid help regulate osmotic pressure， thereby optimizing the fixation effect.

FSA Fixative is a testicular specific fixative， which has a better fixation effect than conventional 10% neutral formalin fixative.