Journal Article

Because historic fluid-preserved museum specimens are often irreplaceable, destructive sampling such as that required by microscopy is rarely possible. As a result, the changes that take place in pigment cells have not yet been well documented. The purpose of this project was to explore the possibilities of light microscopy for the visualisation of chromatophores in fluid-preserved zebrafish. Being able to see the effects of a range of preservation methods in detail expands our understanding of the changes that are taking place when we preserve specimens for our collections. Given the fixation and preservation methods used, it was expected that some level of disruption would occur to the size, shape, and positioning of the different types of pigment cells which make up the zebrafish striping and colouration. In addition to the changes within and between the chromatophores, we also expected to see changes that are caused directly by the biochemical interactions between the zebrafish and the preservation fluids. Microscopy, supported by evidence from fluid-preserved collections in general, confirmed that each of the preservation methods used had a detrimental effect on both structural and chemical pigments. The current project was confined to zebrafish, and the issues inherent in their preservation such as iridescence, layering, and changes to the shape and size of chromatophores, may be entirely different from the considerations required for other organisms. However, understanding the differences between these effects on a microscopic level can pave the way for new practices to be developed in the field of fluid preservation in museums.