Juvenile lamprey ( Lampetra ), scanned with the SkyScan 1174. Fixed in formalin and stained with I2E after storage in alcohol. Whole specimen was approximately 10 cm in length. Top: ventral view of a horizontal cutaway volume rendering. Center: external view of the head region. Bottom: single reconstructed parasagittal section. Voxel size 15 μm. Sample provided by Daniel Sidertis, Univ. Vienna.