Good Holes in the Liver

What am I looking at?

The video starts with an electron microscopy image of a blood vessel in the liver (large white hole) and the surrounding liver tissue (black and white tissue around the hole). The video progresses to a 3D rendering of a hepatic endothelial cell in blue which is filled with holes, or fenestrae. At this stage, we can also see a hepatocyte (liver cell) in yellow visible through the holes in the endothelial cell. Finally, the endoplasmic reticulum of both cells shows up in green towards the end of the video.

Biology in the Background

The liver removes toxins and other small molecules from the bloodstream, produces enzymes and other useful compounds that aid in digestion, and more. The liver uses cells called hepatocytes to accomplish many of these essential functions. These cells can be damaged by overexposure to toxins or fatigue.  

The body has an interesting way of protecting hepatocytes while still allowing them to accomplish their functions. This involves a specialized set of cells that line the exterior of the liver’s blood vessels called hepatic endothelial cells. These cells have holes in them called fenestrae that hepatocytes can poke through, allowing nutrients, drugs, hormones, and other small molecules to pass between the hepatocyte and the bloodstream.  

Videos like these give us a better idea of how hepatocytes interact with the bloodstream and therefore a more complete picture of how the liver functions. This information could be the foundation for future research on liver disease, nutrient processing and absorption, and the production and distribution of molecules produced in the liver.

Mouse hepatic endothelial cells are about 6 micrometers across, roughly 12 times smaller than the width of a human hair. Hepatocytes can grow up to 20 micrometers across, roughly 3.5 times smaller than the width of a human hair.  

Technique

The tissues shown in this video were reconstructed using Focused Ion Beam Scanning Electron Microscopy (FIB-SEM).