Preserving Preserved Tissue


 Euonymous Scale feeding on a leaf;  Histological section

Histologists who study insects at the cellular level may embed an insect in paraffin or plastic then slice the specimen into thin sections to be mounted on a microscope slide and examined.  Paraffin was used to embed insects historically,  but most modern microscopists embed in a plastic resin. To preserve the insect tissue, the specimen is “fixed”, a process that destroys all enzyme activity that might damage or alter the tissue. Once fixed and in paraffin, tissues are assumed to be stable. However, they may not be pest free.

Viennese dermatologists examining some paraffin blocks from the early 1980s found unusual hollows and cavities in the tissue.* The preserved tissues were damaged by dermestid beetles of the Genus, “Anthrenus”. Dermestid will colonize any dead tissue if they have access.  Dermestids are also known to colonize and damage collections of pinned insects.  What to do?  The histologists followed the lead of the insect taxonomists and added naphthalene to the storage container to kill the dermestids prevent further damage.

*Jurecka, W ; Gebhart, W ; Mainitz, M. Anthrenus sp. The paraffin block eater bug. The American Journal of Dermatopathology 1987, Vol.9(3), pp.204-7

About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
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