Effects of different fixation methods on the study of Rhodnius prolixus head using 3D microCT imaging

Chagas' disease, also called American trypanosomiasis, is a human tropical disease, which is endemic in large areas of South and Central America. Rhodnius prolixus is the most important insect vector of Trypanosoma cruzi, the etiologic agent of Chagas' disease. Studies have shown that microcomputed tomography (microCT) provides an excellent tool for 3D reconstruction of Rhodnius prolixus head. Although this approach can produce finely resolved images of internal morphology of insects, the improvement of the contrast between the low density tissues of the insect is somehow necessary so that structures can be better distinguished. An appropriate contrast staining and fixative methodology can produce high-quality images of soft tissues enhancing the contrast of the reconstructed images from microCT. In this work, different fixative methods were used to improve 3D imaging visualization of internal structures of Rhodnius prolixus using microCT. All specimens were imaged at Brazilian Synchrotron Laboratory (LNLS). The fixatives used were gluteroldehyde, Bouin's fluid and Bouin's alcoholic. The results showed relevant differences in the images obtained with different fixatives. This work revealed that it is possible to improve contrast and visibility of details of Rhodnius prolixus and other insects as well, by the appropriate use of fixative and staining methods.