Abstract
Liver cells can be divided into parenchymal cells (hepatocytes) and non-parenchymal cells. The latter cells include Kupffer cells (KCs), pit cells, hepatic stellate cells (HSCs) and liver sinusoidal endothelial cells (LSECs). LSECs comprise the sinusoid, a specialized capillary which has small fenestrations (100 to 150 nm in diameter) in their thin walls. Due to the absence of a basement membrane lining LSECs, small particles and solutes within the blood can pass through the fenestrations freely. Chylomicron (CM) is a large lipoprotein (80 to 1,000 nm in diameter) secreted from intestinal absorptive epithelial cells. During circulation, triglycerides in CM are degraded by lipoprotein lipase and the residual lipoprotein forms a chylomicron remnant (CMR) with a diameter of 30 to 80 nm, which can pass through LSEC fenestrations to reach the hepatocytes. Absorbed vitamin A is incorporated into CM in the intestine and remains within CM/CMR during circulation, until the vitamin is incorporated into hepatocytes.Therefore, the transport and storage of vitamin A is largely affected by the nature of the LSEC fenestration. We could label KCs and HSCs within the rat liver separately by utilizing such a characteristic feature of LSECs.
