Figure 7

Iodine (I2M) staining of methanol-preserved samples. Left: Paddlefish Polyodon spathula, 11 days post-hatching, formalin-fixed and methanol dehydrated for in situ hybridization, stained with I2M. Voxel size 5.1 μm. Right: Green sturgeon (Acipenser medirostris, 65 mm total length; kindly provided by Boyd Kynard of the Conte Anadromous Fish Laboratory, MA) fixed in Dent's and stored in methanol, stained with I2M to demonstrate the pectoral musculature. Iodine tends to overstain calcified tissues: x-ray absorption by bone, scutes, and lepidotrichia is outside the image brightness window in these images. Scale bar = 1 mm. Voxel size 9.2 μm.