The demonstration of B cells in pancreatic islets with orcein.
Orcein stains granules in pancreatic islet cells selectively. The localization of Orcein-positive cells within islets differs from that of Grimelius-stained cells, but corresponds to the B cell type differentiated by Aldehyde Fuchsin. Usually there appear to be fewer Orcein-positive cells than Aldehyde Fuchsin-positive ones. This indicates either that Aldehyde Fuchsin is a more sensitive stain for B cells or that Orcein is a more selective stain for a B cell type subpopulation. The rationale of the Orcein reaction in B cells seems to depend on the oxidation of disulphide bonds present in insulin and its precursors rich in cystine.
D006801:Humans; D007515:Islets of Langerhans / Q000166:cytology*; D010078:Oxazines / Q000138:chemical synthesis; D012394:Rosaniline Dyes; D012835:Silver Nitrate; D013194:Staining and Labeling
D010078:Oxazines; D012394:Rosaniline Dyes; C002313:PAcein; D012835:Silver Nitrate