Liver sinusoid

{{Short description|Hepatic sinusoidal blood vessel}}

{{Infobox anatomy

| Name = Liver sinusoid

| Latin = vas sinusoideum

| Image = Sinusoid.jpeg

| Caption = Sinusoid of a rat liver with fenestrated endothelial cells. Fenestrae are approx 100 nm diameter, and the sinusoidal width 5 µm.

| Image2 = Hepatic structure2.svg

| Caption2 = Basic liver structure

| Precursor =

| System =

| Artery =

| Vein =

| Nerve =

| Lymph =

|DrainsTo=Central veins of liver|DrainsFrom=Hepatic portal vein}}

A liver sinusoid is a type of capillary known as a sinusoidal capillary, discontinuous capillary or sinusoid, that is similar to a fenestrated capillary, having discontinuous endothelium that serves as a location for mixing of the oxygen-rich blood from the hepatic artery and the nutrient-rich blood from the portal vein.[http://www.siumed.edu/~dking2/erg/liver.htm#sinusoids SIU SOM Histology GI]

The liver sinusoid has a larger caliber than other types of capillaries and has a lining of specialised endothelial cells known as the liver sinusoidal endothelial cells (LSECs), and Kupffer cells.{{cite journal |last1=Brunt|display-authors=etal|first1=EM |title=Pathology of the liver sinusoids. |journal=Histopathology |date=June 2014 |volume=64 |issue=7 |pages=907–20 |doi=10.1111/his.12364 |pmid=24393125|s2cid=12709169}} The cells are porous and have a scavenging function.{{cite journal |last1=DeLeve |first1=LD |title=Hepatic microvasculature in liver injury. |journal=Seminars in Liver Disease |date=November 2007 |volume=27 |issue=4 |pages=390–400 |doi=10.1055/s-2007-991515 |pmid=17979075}} The LSECs make up around half of the non-parenchymal cells in the liver and are flattened and fenestrated.{{cite journal |last1=Xing |first1=Y |last2=Zhao |first2=T |last3=Gao |first3=X |last4=Wu |first4=Y |title=Liver X receptor α is essential for the capillarization of liver sinusoidal endothelial cells in liver injury. |journal=Scientific Reports |date=18 February 2016 |volume=6 |pages=21309 |doi=10.1038/srep21309 |pmid=26887957|pmc=4758044 |bibcode=2016NatSR...621309X }} LSECs have many fenestrae that gives easy communication between the sinusoidal lumen and the space of Disse. They play a part in filtration, endocytosis, and in the regulation of blood flow in the sinusoids.{{cite journal |last1=Arii |first1=S |last2=Imamura |first2=M |title=Physiological role of sinusoidal endothelial cells and Kupffer cells and their implication in the pathogenesis of liver injury. |journal=Journal of Hepato-biliary-pancreatic Surgery |date=2000 |volume=7 |issue=1 |pages=40–8 |doi= 10.1007/s005340050152|pmid=10982590}}

The Kupffer cells can take up and destroy foreign material such as bacteria. Hepatocytes are separated from the sinusoids by the space of Disse. Hepatic stellate cells are present in the space of Disse and are involved in scar formation in response to liver damage.

Defenestration happens when LSECs are lost rendering the sinusoid as an ordinary capillary. This process precedes fibrosis.{{cite journal |last1=Xie |first1=G |last2=Wang |first2=X |last3=Wang |first3=L |last4=Wang |first4=L |last5=Atkinson |first5=RD |last6=Kanel |first6=GC |last7=Gaarde |first7=WA |last8=Deleve |first8=LD |title=Role of differentiation of liver sinusoidal endothelial cells in progression and regression of hepatic fibrosis in rats. |journal=Gastroenterology |date=April 2012 |volume=142 |issue=4 |pages=918–927.e6 |doi=10.1053/j.gastro.2011.12.017 |pmid=22178212|pmc=3618963 }}