Dehydrate with ethanol, clear with xylene and mount with a resinous medium.
Oxidisable carbohydrates – blue
Reducing substances – blue
Nuclei – red
It is well known that metallic azides can be explosive. However, thiosemicarbazide is not a
simple metallic azide and is not explosive.
The MSDS from J. T. Baker (via the SIRI database) says:
Flash Point: N/A
Lower Explosive Limit: N/A
Upper Explosive Limit: N/A
Unusal Fire and Expl.rds: NONE IDENTIFIED
Reducing substances which may be present are also coloured blue.
This includes melanin and enterochromaffin. Others may also be seen.
If acid hydrolysis is used instead of periodic acid oxidation
(as in Feulgen's nucleal reaction), nuclei are coloured blue.
No attempt has been made to identify the substance coloured.
The Schmorl's solution is from Lillie's modification of Schmorl's ferricyanide
reduction method for tissue reducing substances.
There is a modification of this technique for
Thiosemicarbazide has a hydrazine group at one end of it's molecule and a thiocarbamyl group at the other.
The hydrazine group combines with any aldehydes generated by periodic acid oxidation, and in so doing attaches the
thiocarbamyl group to the carbohydrate. The thiocarbamyl group is a more powerful reducing group than are aldehydes and
rapidly reduces ferricyanide to ferrocyanide, which is immediately trapped by the ferric salt to form prussian blue
at the site.
Reference Hayashi, I., Tome, Y. and Shimosato, Y., 1989 Thiosemicarbazide used after periodic acid makes methenamine silver staining of renal glomerular basement membranes faster and cleaner.
Stain Technology, v 64, p 185.
Lillie, R.D., (1954) Histopathologic technique and practical histochemistry Ed.2
Blakiston, New York, USA.