Whole-Fish: Fixed larvae were washed with phosphate buffered saline (PBS) for 5 min, and then penetrated by 20, 40, 80 and 100% 1,2-propanediol (Sigma, United States) each for 15 min. Then stained with 0.5% Oil Red O (Sigma, United States) at 65°C in the dark for 1 h. The zebrafish larvae were then incubated in 100% 1,2-propanediol at room temperature for 1 h, and eluted with 80, 40, and 20% 1,2-propanediol each for 10 min. Finally, larvae were imaged by an Olympus U-HGLGPS microscope (Tokyo, Japan).
Cryosections: Fixed zebrafish larvae were dehydrated in 30% sucrose at 4°C for 3 days. After being embedded in optimal cutting tissue (OCT) compound (Leica, Germany), larvae were cut into 14 μM sections. Frozen sections were washed with PBS to remove OCT, incubated in 100% 1, two propylene glycol for 5 min, then stained with 0.7% Oil Red O for 10 min at 60°C, finally eluted with 85% 1,2-propylene glycol and rinsed with PBS to keep the background clean. The slices were imaged with a Nikon Eclipse Ni-U optical microscope (Nikon, Tokyo, Japan).
Cell slides: Fixed cell slides were washed with PBS for 15 min, then incubated with 100% 1,2-propanediol for 10 min. After being stained with 0.7% Oil Red O and decontaminated with 85% 1,2-propanediol and PBS, the slides were imaged with Nikon Eclipse Ni-U optical microscope (Nikon, Tokyo, Japan).
Cryosections: Fixed zebrafish larvae were dehydrated in 30% sucrose at 4°C for 3 days. After being embedded in optimal cutting tissue (OCT) compound (Leica, Germany), larvae were cut into 14 μM sections. Frozen sections were washed with PBS to remove OCT, incubated in 100% 1, two propylene glycol for 5 min, then stained with 0.7% Oil Red O for 10 min at 60°C, finally eluted with 85% 1,2-propylene glycol and rinsed with PBS to keep the background clean. The slices were imaged with a Nikon Eclipse Ni-U optical microscope (Nikon, Tokyo, Japan).
Cell slides: Fixed cell slides were washed with PBS for 15 min, then incubated with 100% 1,2-propanediol for 10 min. After being stained with 0.7% Oil Red O and decontaminated with 85% 1,2-propanediol and PBS, the slides were imaged with Nikon Eclipse Ni-U optical microscope (Nikon, Tokyo, Japan).