FIG. 1.

Experimental scheme for observing zebrafishes fed with control or high-cholesterol diet (HCD). When zebrafish larvae start free feeding (5 days postfertilization [dpf]), normal diet or HCD starts, and feeding is continued for 33 or 40 days. Lower figures show representative photographs of 38 and 45 dpf juvenile zebrafishes. The total body lengths of the 38 and 45 dpf models are about 10 and 13 mm, respectively. Barium sulfate was injected into the vessels to observe the blood vessels of a zebrafish sample. Zebrafish was fixed in formalin and stained with osmium tetroxide and uranyl acetate. The fish was then embedded in Spurr's resin for X-ray microscopy and scanned in the resin block. Upper figures show a typical phase-contrast X-ray image of a 38 dpf zebrafish and its 3D rendering image. Nile red and Oil red O staining methods and two-photon microscopy technique were performed to identify adipocytes or lipid droplets in zebrafish models and to compare with synchrotron X-ray micro-computed tomography (SR-μCT) images. Paraffin sectioning (10 μm thickness) and EVG staining were also carried out to compare PSR-μCT images with histological sectioning images.