Comparison of five elastin histochemical stains to identify pulmonary small vasculature

Optimization of an elastic tissue histochemical stain to enable clear, crisp visualization and quantification of pulmonary small vasculature is central to the histomorphologic quantitation of pulmonary vasculature wall thickness. To accomplish elastic tissue histochemical stain optimization, five histochemical elastin stains were compared to identify the internal and external elastic laminae of small arteries (50–100 μm in external diameter) to very small intra-acinar vessels (10–50 μm in external diameter) in rat lung tissue sections. The five elastin stains included: a modified Verhoeff’s elastin stain, Miller’s elastic van Gieson, and three modifications of the Miller’s stain. The Miller elastin stain is a progressive procedure that does not require a differentiation step, thus enabling consistency and reliability of staining from slide to slide. A modified Miller’s histochemical staining methodology successfully highlighted the pulmonary small caliber vasculature wall thickness. The modified method was technically easier and less time consuming to perform than regressive methods. To improve elastin-to-background contrast, modifications to the Miller’s stain included bypassing the nuclear staining and using a neutral red counterstain in place of the van Gieson counterstain, both of which greatly facilitated observer-assisted pulmonary vascular structure identification for histomorphometric quantitation.