Orcein as a mucin stain for gastrointestinal tissue sections.

Although orcein has been in use for a long time as a stain for elastic fibres, it is only recently that it has been rediscovered for the demonstration of a variety of other substances. These include hepatitis B surface antigen (HBsAg),' 2 copper-associated protein,34 and more recently, intestinal sulphated mucins.35 Sipponen5 studied the normal distribution of orceinpositive mucin in the gastrointestinal tract and compared the results with those obtained by other mucin stains. We here report our findings using a slightly modified orcein staining method after oxidation, on a variety of gastrointestinal lesions as well as normal gastrointestinal tissues.