Absence of Free Aldehydes in Fresh Tissues, as Shown with a Neutralized Schiff Reagent

Abstract

A neutralized Schiff's reagent (pH 6.7) was prepared and used to investigate the role of the acidic nature of the routine Schiff's reagent (pH 2.6) in the plasmal reaction. The neutralized reagent was satisfactory as an aldehyde reagent in the nucleal reaction on gut and, although giving a less intense reaction than the routine reagent in the PAS reaction on the gut and plasmal reaction on the aorta, was satisfactory here in respect to localization and thus to aldehyde specificity. Control sections for the plasmal reaction of unfixed nerve and aorta gave positive results when placed in the routine Schiff's, this increasing with time left in the reagent. Similar control sections in the neutralized Schiff's reagent remained consistently negative even though left in this reagent for 0.5 hr. The positive reaction of such control sections is apparently due to acid hydrolysis of labile plasmalogens by the routine Schiff's reagent in myelin and elastin and not to the presence of “free” aldehydes in these tissue elements