Alizarin (madder) has been used in textile dyeing since early antiquity. In histology calcium-alizarin or calcium-alizarin red S compounds are often referred to as "lake" or "complex." Chemical and infrared spectroscopic data showed that these compounds are salts, not chelates. In dye chemistry the term lake denotes a poorly soluble or insoluble salt of a water-soluble dye. Salt formation between calcium deposits in tissues and alizarin or alizarin red S is indicated by the sensitivity of these compounds toward dilute acetic acid. Acid dyes for lakes, which do not contain chelating groups, also stained calcium deposits selectively. Alizarin stained calcium deposits intensely only around pH 12. Alizarin red S colored calcium deposits selectively around pH 9; neutral and acid dye solutions produced severe diffusion artifacts. Chemical data indicate that alizarin red S can react with calcium via its sulfonic acid and/or its OH groups.

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Lubricant contamination of ThinPrep cervical cytology samples may result in reduced cellularity of the subsequent slide. This study provides evidence-based data to support British Society for Clinical Cytology recommendations for no lubricant use when taking cervical samples.

Electron microscopists have described in vascular endothelial cells filaments which resemble myofibrils. These fibrils cannot be demonstrated with conventional staining techniques. On the basis of previous investigations of relations between dye structure and affinity for muscle fibres, a staining method for demonstration of myoendothelial cells by direct, polarization and fluorescence microscopy has been developed. Carnoy-fixed paraffin sections were treated consecutively with Kernechtrot, tannic and phosphomolybdic acid and counterstained with Levanol fast cyanine 5RN. This procedure stained myoendothelial cells and muscle fibres deep blue, connective tissues yellow and nuclei pink. For polarization and fluorescence-microscopic studies thiazine red R was substituted for Levanol fast cyanine 5RN and Kernechtrot was replaced by Mayer's acid haemalum. The light-microscopic characteristics of fibrils in endothelial cells and in smooth muscle cells were identical.Correlation of light-microscopic observations with electron-microscopic data supported the conclusion that the staining procedure indeed demonstrates myofilaments in endothelial cells. Formation of multiple layers of myoendothelial cells was observed in areas of thickening of the intima, while the cells in the deeper layers became indistinguishable from smooth muscle cells. These findings support earlier concepts of the transformation of endothelial cells into intimal muscle cells.