A histochemical method able to detect vitamins D and to discriminate it from cholesterol and its esters

A suitable histochemical method able to discriminate vitamins D and 7-dehydrocholesterol from cholesterol and its esters is proposed taking into account the alkaline permanganate-toluidine blue reaction, the alkaline permanganate-Schiff reaction and the inhibitory effect of the HgCl2-formalin fixative. This method appears specific according to the results provided by spot test. On tissue sections the alkaline permanganate-toluidine blue reaction is more sensitive and more specific than the alkaline permanganate-Schiff reaction. A previous ribonuclease treatment or the methylation effect improves the specificity of the alkaline permanganate-toluidine blue reaction. The 2.4-dinitrophenylhydrazine blockade must be used previously to the alkaline permanganate-Schiff reaction as an attempt to improve its specificity. The previous hydrolysis carried on by some suitable treatments seems very useful to detect masked vitamins D and 7-dehydrocholesterol. The oxidized products accountable for the reactivity of vitamins D and 7-dehydrocholesterol to the alkaline permanganate-toluidine blue and alkaline permanganate-Schiff reactions were discussed.