Fenestrations in the Liver Sinusoidal Endothelial Cell

Three-dimensional structured illumination microscopy of liver sinusoidal endothelial cell fenestrations

“…Furthermore, scanning EM may underestimate the size of fenestrations particularly in intact liver samples because of drying methods and gold coating (Braet et al, 2007). Transmission EM is limited by the number of fenestrations that are counted on cross section and the inability to determine whether the fenestration has been transected at its longest diameter (Cogger and Le Couteur, 2009). Recently, AFM was able to image fenestrations in fixed wet isolated LSECs (Braet et al, 2007), however AFM cannot be used with fluorescent markers.…”

“…The mean diameter of the fenestrations was 123±24 nm and there were 26±14 fenestrations in each sieve plate. Using EM, fenestrations have been reported to have diameters ranging from 50–170 nm in different species (Cogger and Le Couteur, 2009) and with AFM, LSECs had a diameter of 223 nm and a depth of 183 nm (Braet et al, 2007). These results are consistent with those observed in this study using SIM.…”

“…Fenestrations are fully patent, non-diaphragmed pores that connect the luminal membrane with the extracellular membrane of LSECs. Most fenestrations are clustered together in groups of 10–100 called liver sieve plates, which occupy 2–20% of the LSEC surface (Cogger and Le Couteur, 2009; Fraser et al, 1995; Wisse et al, 1985). …”

“…While both techniques can yield ultrastructural morphology, they also have significant limitations. EM requires fixatives and treatment of tissue with resins and dehydration, resulting in a lack of temporal information, and the inability to utilize versatile and specialized probes including genetically encoded fluorescent proteins and concentration-sensitive ion indicators (Braet et al, 2007; Cogger and Le Couteur, 2009). AFM yields formidable topographic physical information, but again without specific markers.…”

“…In addition, the cytoplasmic extensions of the LSECs are technically difficult to assess by AFM because they are extremely thin (Braet et al, 2007). Furthermore, both imaging techniques are relatively low-throughput which handicaps exhaustive studies (Cogger and Le Couteur, 2009). …”