Selective staining of pancreatic beta-cell granules. Evolution and present status

Presented herein are the rationale, evolution, and present status of the alcian blue (AB)-aldehyde pararosaniline (AP) method for the selective staining of pancreatic beta-cell granules in paraffin sections of fixed tissues. Acidic mucins of pancreatic ductal and ductular cells and granules of mast cells and basophils normally stain strongly with AP; prestaining them with AB prevents their staining with AP. After AB staining, only certain islet cells, assumed to be beta, and cells of insulinomas bind AP strongly. Detailed working procedures are provided for the primary method (A) and two variants (B and C). The stainability of beta-cell granules in paraffin sections depends on the adequacy of primary fixation.