Low inherent contrast in soft tissues has been limiting the use of X-ray absorption micro-computed tomography (micro-CT) to access high-resolution structural information of animal organs. The staining agents used in micro-CT to improve the contrast fail in providing high-quality images of whole organs of animals due to diffusion problems of the staining agent into the sample. We demonstrate a staining protocol that incorporates a biochemical conditioning step prior to exposure to the staining agent that succeeds in overcoming the diffusion problems, thus quickly providing high-quality micro-CT images of whole organs of mammals. Besides of yielding non-distorted three-dimensional information at the same spatial resolution accessible in histological sections, micro-CT images of whole organs stained by our method enable easy screening of slices along any direction of the volume thus demonstrating new possibilities of structural analysis in biomedical science.

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In insects, females can keep sperm capable of fertilisation over a long period with the help of the spermatheca. The effectiveness of storing fertile sperm is expected to reflect in the reproductive strategy and, thus, the morphology of the involved organs. In this work, we focused on the relationship between reproduction and morphology in the haplodiploid Thysanoptera, especially if a loss of these traits occurs under thelytoky. The spermathecal morphology and the fate of stored spermatozoa were studied by microscopic techniques (high-resolution x-ray computed tomography and transmission electron microscopy) in three species with different reproductive modes and lifestyles (Suocerathrips linguis, Echinothrips americanus, Hercinothrips femoralis). Mating experiments were conducted to analyse the use of the transferred sperm in the thelytokous H. femoralis. Results show that the spermathecae are relatively simple, which can be explained by the availability of sperm and the short lifespan of the females. However, the spermatheca in H. femoralis seems to be vestigial compared to the arrhenotokous species and females do not use sperm for fertilisation. No substantial change was observed in the structure of spermatozoa, despite an enlargement of the sperm organelles being measured during storage in all three species. The results of this work demonstrate differences in the morphology of the spermatheca, especially concerning the reproduction mode, promoting the understanding of the complex interaction between morphology and behaviour.