Igestive tract. Resolution: (81 μm), no contrast agent added. The two specimens show a high degree of similarity in their overall internal architecture. Arrows indicate paramagnetic gut content. (C), (D) Effects of a contrast agent on image quality. MRI sections at the height of perignathic girdle and lower stomach. Resolution: (81 μm). This freshly fixed specimen was scanned (C) before and (D) after the application of a contrast agent, Magnevist. Arrows indicate susceptibility artefacts. (E), (F) Comparison of a freshly fixed and a museum specimen. MRI sections at the height of gonads and upper oesophagus. Resolution: (81 μm). The 135-year-old museum specimen (F) gives imaging results comparable to the freshly fixed specimen (E). Both specimens were scanned with contrast agent added. Orientation: ambulacrum II facing upwards. Scale bar: 0.5 cm. ac, axial complex; al, Aristotle's lantern; am, ampulla; es, oesophagus; go, gonad; im, interpyramidal muscle; in, intestine; is, inner marginal sinus; l m, lantern muscle; os, outer marginal sinus; pg, perignathic girdle; re, rectum; si, siphon; st, stomach; to, tooth.<p><b>Copyright information:</b></p><p>Taken from "Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging"</p><p>http://www.biomedcentral.com/1741-7007/6/33</p><p>BMC Biology 2008;6():33-33.</p><p>Published online 23 Jul 2008</p><p>PMCID:PMC2500006.</p><p></p
