Meeting Abstract
The treatment of vertebrate specimens with radio-opaque substances to enhance soft-tissue contrast in CT scans has revolutionized morphological analysis. DiceCT has produced spectacular results and involves immersing specimens in Lugol’s iodine. A shortcoming of diceCT is that diffusion (the “d” in “diceCT”) can take days, weeks, or months in large, intact, unskinned specimens. Moreover, long diffusion times can cause marked shrinkage. Alternatively, our team has developed spiceCT, which involves perfusing specimens with Lugol’s iodine, yielding excellent results—literally within hours. The vascular system of thawed, unfixed, unskinned specimens (mostly birds thus far) is cannulated, and then hypertonic (2.5 or 5%) aqueous Lugol’s iodine is injected with a syringe. The solution perfuses well, easily filling capillary beds. Perfusion can be visually monitored in key areas, as well as tactilely via syringe pressure. Staining is rapid, and specimens can be scanned immediately, yielding same-day results. There is no time for shrinkage. The absence of prior fixation shortens processing time and also opens new avenues for final storage in that the specimen can be fixed, refrozen, or even skeletonized. Perfusion rather than diffusion also allows targeting of tissues—selective perfusion (the “sp” of “spiceCT”)—by injecting their vascular supply. One shortcoming of spiceCT is that iodine is too large to cross the blood-brain barrier (BBB), and thus the method is not currently useful for studying brain anatomy, although our team is exploring ways to overcome this problem. SpiceCT is intended to supplement, not replace, diceCT in the toolkit of morphologists.
