Histochemistry on vibratome sections of fish tissue: a comparison of fixation and embedding methods

Abstract

Despite improvements in imaging techniques during recent years, for many non-model systems the fixation of tissues followed by embedding and sectioning for histochemical or immunohistochemical staining remains an important technique in vertebrate histology. The present study sets out to explore the preservation of histological sections of fish tissues using different preparation techniques. The quality of transverse vibratome sections from trunk segments of the lesser-spotted dogfish Scyliorhinus canicula, Atlantic sturgeon Acipenser oxyrinchus and zebrafish Danio rerio were compared using different fixatives (formaldehyde, paraformaldehyde and zinc-formaldehyde) and embedding methods (gelatine, agarose and low-temperature melting agarose). Our data show that the quality of the vibratome sections for histochemical staining is strongly dependent upon fixation and embedding media. Although paraformaldehyde fixation results in a more pronounced shrinkage of the trunk segment than the other fixatives used , the quality of the sections and the histochemical staining was best with this fixative in zebrafish and dogfish. Additionally, the embedding methods have a strong influence on the quality of the sections. In the dogfish and sturgeon samples, the preferred embedding media were agarose and low-temperature melting agarose, since gelatine often caused shrinkage of the tissues. In conclusion, for histochemical examinations, the processing protocols for vibratome sectioning need to be adapted individually to each study organism.