This is a difficult one! Ferric ammonium sulphate (iron alum) isn't the only metal salt used as a "sensitizer" between the permanganate oxidation and the ammoniacal silver. Other methods use a uranyl salt or silver nitrate (cf Bielschowsky and its variants), and probably there are others. In some methods this step is omitted. The trouble is that calling the iron alum or other solution a "sensitizer" isn't really saying anything. One could speculate on possible chemical reactions, especially for a ferric salt, but speculations need experimental testing.
The two best papers that I know on mechanisms involved in these methods are: Velican C & Velican D 1970. Acta Anat. 77: 540-559 and Puchtler H & Waldrop FS 1978 Histochemistry 57: 177-187. The second of these includes experimental work and extensive literature review and concludes that ". . . silver impregnation technics for reticulum fibers have no chemical significance and cannot be considered as histochemical technics for "reticulin" or type III collagen". Note the different usage of "reticulum fibers" (histology) and "reticulin" (from late 19th century biochemistry). The Velicans provided evidence supporting the detection of aldehydes produced by oxidation of carbohydrate components associated with reticulum fibres and basement membranes. If anyone knows of histochemical investigations in this field more recent than 1978, please let us all know. John Kiernan Anatomy, UWO London, Canada = = = ----- Original Message ----- From: Gudrun Lang <gu.l...@gmx.at> Date: Thursday, February 18, 2010 9:07 Subject: [Histonet] reticulin stain Gomori To: histonet@lists.utsouthwestern.edu > Hi all! > > Today I was asked if I knew the chemistry behind the ammonia- > iron-sulfat > NH4Fe(SO4)2 . 12H2O reaction in the reticulin stain of Gomori. > > I couldn't help so I forward the question to the histonet comunity. > > I hope, someone has a suggestion for me. > > > > Gudrun Lang > > _______________________________________________ > Histonet mailing list > Histonet@lists.utsouthwestern.edu > http://lists.utsouthwestern.edu/mailman/listinfo/histonet _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet
