Nonalcoholic Bouin’s fixative

75 mL saturated picric acid solution (Sigma)

25 mL formalin (37% formalin in water with no methanol; Fisher Scientific)

5 mL glacial acetic acid

Prepare fresh (<1 wk old). Store at 4ºC.

Methanol in formalin will produce bouton shrinkage and give poor results with certain antibodies.