The pros and cons of using micro-computed tomography in gross and microanatomical assessments of polychaetous annelids

Abstract

Paterson, G.L.J., Sykes, D., Faulwetter, S., Merks, R., Ahmed, F., Hawkins, L.E., Dinley, J., Ball, A.D. and Arvanitidis, C. 2014. The pros and cons of using micro-computed tomography in gross and micro-anatomical assessments of polychaetous annelids. Memoirs of Museum Victoria 71: 237-246.The use of micro-CT scanners in the study of anatomy and functional morphology of marine invertebrates is becoming more common. The advantages and disadvantages of this methodology for the study of the internal anatomy of polychaetes are discussed. Soft-bodied invertebrates such as polychaetes pose some specific problems. It can be difficult to gain sufficient contrast between different types of tissues to be able to image them with X-rays. A range of stains can help enhance the contrast between tissues. In this study we investigate a number of stains, concentrating on those considered reversible. The advantages of such stains in the study of museum specimens and the resulting possibilities for large-scale comparative morphology studies are outlined.

Sea Anemones through X-Rays: Visualization of Two Species ofDiadumene(Cnidaria, Actiniaria) Using Micro-CT

“…Utility of microcomputed CT scanning for the taxonomy of Actiniaria: In this study we evaluate the utility of micro-CT imaging for the taxonomy and systematics of sea anemones, which has been possible only as a result of recent protocol modifications of contrast enhancement in soft-bodied invertebrates (e.g., Metscher, 2009aMetscher, , 2009bFaulwetter et al, 2013aFaulwetter et al, , 2013bDescamps et al, 2014;Paterson et al, 2014;Fernández et al, 2014;Tessler et al, 2016;Holst et al, 2016). The appeal of micro-CT scanning for sea anemone studies is its potential to facilitate and improve characterization of morphological characters used in the taxonomy of the group especially in regard to the tridimensional anatomical representations based on of micro-CT images.…”

“…Although micro-CT scanning speeds up the stage of obtaining data, unless the access to a micro-CT is unlimited (which was not the case for this study), the number of specimens scanned (i.e., low; one specimen in this study) prevents detection of variability and differences at the species level. Similarly, the nondestructive nature of micro-CT scanning is often proclaimed as a clear advantage of this method over dissections, and particularly over histology (Metscher, 2009a(Metscher, , 2009bDinley et al, 2010;Paterson et al, 2014;Nesteruk and Wiśniewski, 2015;). In our case, however, osmium tetroxide irreversibly changes tissue characteristics (Faulwetter et al, 2013a) and cannot be washed off after scanning (Fernández et al, 2014), rendering the specimens unusable for any other purpose.…”

“…For the present study, the distinction is moot, since members of Diadumene do not possess marginal sphincter musculature. Given technical properties of the scanner, resolution is a trade-off between size and scanning time with higher resolution achieved faster in smaller specimens (Paterson et al, 2014). The muscle fibers of retractors, parietal or marginal sphincter musculature, for example, are probably at the resolution limit of the micro-CT scanner and cannot be portrayed with an appropriate resolution for proper observation.…”

Variation in Brain Morphology of Intertidal Gobies: A Comparison of Methodologies Used to Quantitatively Assess Brain Volumes in Fish

“…Since micro-CT is still only a recently established technique in small-animal imaging, obtaining the most useful set of scanner parameters (e.g. scanning time, filters, Xray energy and wavelength) for different types of specimens and developing a contrast stain that will highlight the specific tissues needed for investigation can cause issues for micro-CT users [Bartling et al, 2007;Metscher, 2009a, b;Paterson et al, 2014]. If system settings and contrast stains are not ideal, then micro-CT images may exhibit poor tissue contrast (i.e.…”

Micro-CTvlab: A web based virtual gallery of biological specimens using X-ray microtomography (micro-CT)

“…Marxen et al 2007, Metscher 2009, O’Connor et al 2010) and functional morphology (e.g. Nickel et al 2006, Curtis et al 2009, Wojcieszek et al 2012, Schulz-Mirbach et al 2013, Paterson et al 2014). This imaging technology gives the user the option to visualise both external (morphology) and internal (anatomy) characteristics of a specimen, to rotate and virtually dissect the resulting three-dimensional (3D) representation, as well as to perform 3D measurements and analyses.…”