Use of roselle extracted from for histological staining: a critical review and rational stain formulation.

Roselle is the common name for a mixture of anthocyanin dyes derived from the plant, . During the past two decades, a sizable, but conflicting, body of literature has supported the use of roselle as a biological stain, and more specifically as a substitute for hematoxylin for staining nuclei selectively. We review the literature and suggest a rational explanation for divergent findings. When used without oxidation and mordanting, roselle is an indiscriminate oversight stain. With appropriate oxidation and mordanting, roselle can be an effective nuclear stain. We propose here use of a stain that is formulated rationally and followed by treatment in a differentiating solution that also acts as a counterstain. We also offer suggestions for improving roselle for the general scientific community.