Staining Methods to Distinguish between Fungi and Erythrocytes in Ancient Tissue Histology

摘要

Skeletal remains from ancient populations are usually the only material left for archaeologists to examine. Multidisciplinary research has revealed structures consistent with the same shape and size as modern erythrocytes in ancient bone marrow and skeletal tissue. These findings have been questioned because postmortem fungi contamination has a similar morphology to erythrocytes. Due to the risk of fungi contamination, identification of erythrocytes by specific proteins using immunohistochemical staining has been considered a requirement for accuracy. However, immunohistochemical staining only demonstrates that the target protein is present on the cell surface and if the protein is degraded, the researcher may misclassify an erythrocyte as a contaminant and loose information.We provide an alternative approach using dyes that can verify erythrocytes, hemosiderin, and fungi but does not require specific cell-surface proteins. This method requires less time and is not as costly as immunohistochemical studies. Staining with dyes can provide important information of the quality of the sample before advanced procedures are employed. Paraffin-embedded demineralized bone sections from archaeological excavations of two Bronze Age burials and commercially available control Aspergillus, slides were stained using haematoxylin and eosin (H&E), PAS staining with a Schiff reagent to detect fungi (carbohydrates), and an iron-specific stain that detects hemosiderin in degraded erythrocytes. Our research demonstrates that it is possible to distinguish between erythrocytes and fungi using a combination of staining techniques.