Silver‐stained structures (AgNORs), their dependence on tissue fixation and absence of prognostic relevance in rectal adenocarcinoma

Abstract

The value of a one‐stage silver staining technique for nucleolar organizer region (NOR)‐associated protein was investigated as a predictor of clinical outcome in 100 rectal adenocarcinomas. In formalin‐fixed tissues, a variety of silver‐stained structures ranging from 0·5 to 7 μm are seen, the abundance of which bears no relation to prognosis, cell proliferation, or ploidy. Evidence is presented that the silver‐stained structures are the result of coalescence of smaller particles caused by formalin fixation, and that assessment of NOR activity is not reliable in routinely formalin‐fixed archival tissues.