Some investigations of the mechanism of the so-called "methylation" reactions used in mucosubstance histochemistry. I. "Methylation" with methyl iodide, diazomethane, and various organic solvents containing either hydrogen chloride or thionyl chloride.

Abstract

The results reported in this paper substantiate Vilter's (1968) hypothesis that the absence of basophilia of acid mucosubstances after a so-called histochemical methylation with acidified methanol may be due to, among other factors, the lactonisation of carboxyl groups rather than, as is generally held, their esterification. Sections from several fixed tissues of Syrian hamster and mouse were treated at 60 ° or at room temperature with dry methanol, ethanol, butan-l-ol, benzene or cyclohexane containing 0.35% hydrogen chloride or 1% thionyl chloride. Others were treated with methanolic methyl iodide or etheral diazomethane. With most of these solutions, the azurophilia attributable to mucosubstance carboxyl and sulphate half-ester groups was eventually abolished; subsequent saponification restored only the azurophilia due to carboxyl groups. However, some variation was found for each “methylating” agent, and also between different mucosubstances.