PRESERVATION OF TOTAL, LYO-, AND DESMOENZYME ACTIVITY IN MAMMALIAN SALIVARY GLANDS FOLLOWING CHLORAL HYDRATE FORMALIN FIXATION

Acid phosphatase, alkaline phosphatase, nonspecific esterase, pseudocholinesterase, leucine aminopeptidase, and β-d-galactosidase activities of parotid and submandibular salivary glands were evaluated in six animal species. Assays for total enzyme, lyoenzyme, and demoenzyme were performed on unfixed and chloral hydrate formalin (CHF) fixed frozen cryostat sections. Following fixation lyoenzyme (soluble fraction) activity exhibited extreme reduction for all enzymes except pseudocholinesterase, while the demoenzyme (insoluble fraction) activity of acid phosphatase, nonspecific esterase, pseudocholinesterase, and β-d-galactosidase was maintained at a high level or increased. Since removal of lyoenzyme activity and retention of desmoenzyme activity are requisites in histochemical localization, this fixative may be the preferred method for handling tissues prior to the localization of the above cited enzymes. Several hypotheses are proposed to explain the increased desmoenzyme (nonspecific esterase and β-d-galactosidase) noted subsequent to fixation.