Two techniques for electron opaque staining of elastic fibres using tannic acid in fresh and formalin fixed tissue.

Two electron microscopic staining techniques, one using tannic acid-glutaraldehyde as a fixative, and the other using tannic acid-uranyl acetate solution as a stain on ultra-thin sections of glutaraldehyde fixed material, were directly compared for elastic fibre staining on several human and animal tissues. Various concentrations of tannic acid were compared using both techniques. The two techniques were also compared on formalin fixed tissues. The use of tannic acid-uranyl acetate solution as a stain on processed tissue is by far the more consistent technique and achieves equally good results on glutaraldehyde or formalin fixed tissue. It is suggested that the use of the term tannic acid technique/method should be reserved for this particular method to achieve a meaningful interpretation of results in scientific papers.