An Easy-to-Use Histological Technique for Small Biological Samples of Senegalese Sole Larvae

Abstract

Histological techniques are a traditional and essential tool for adequately comprehending cellular morphology and physiology in several scientific fields, including ecotoxicological studies. Although bioassays generally recommend using small test organisms, based on advantages such as low maintenance costs and the possibility of a higher number of replicates, the histological process of such organisms is still challenging due to the difficulty of handling them. The present study proposes an accessible protocol for performing the histology of a biological sample of 8 mm maximum length and using histopathological biomarkers in Senegal sole larvae for ecotoxicological tests. Eight-day old larvae of Solea senegalensis obtained from breeders’ natural spawns in cultivation conditions were submitted to histological processing by an adjusted protocol comprising fixation, agarose array pre-embedding, dehydration, paraffin embedding, slides’ preparation, and image analysis by light optical microscope coupled to a digital camera. Low-cost and easy-to-use alternatives were applied in the technique execution. The histological steps were detailed, and S. senegalensis morphological features were presented. This can be considered valuable background information for ecotoxicological studies where changes in cell morphology and physiology are expected.

A web-based histology atlas for the freshwater sentinel speciesDaphnia magna

“…Therefore, the ability to generate consistent sections in each of these planes is essential. Agarose pre-embedding using mold or array facilitates consistent positioning and orientation of millimeter-size samples for sectioning (37,38). We have applied this criterion to D. magna sections, using custom-designed plastic mold to create agarose blocks with wells that hold individual fixed D. magna samples prior to tissue processing and paraffin embedding.…”

“…Agarose embedding using a mold or an array facilitates consistent positioning and orientation of millimeter-size samples for sectioning (37,38). Adapted from Sabaliauskas et al (2006) (39), a mold was designed and 3D -printed for casting an agarose block with wells that could hold up to 18 adult D. magna for concurrent tissue processing and sectioning .…”