The Liver Up Close  　　When viewed under a microscope, the liver is seen as large network of units called hepatic lobules. The hepatic lobule is very small and looks like a six-sided cylinder. 　　The lobule itself is surrounded by connective tissue and has 5 to 7 clusters of vessels around its edges. These vessels include a branch of the portal vein, a branch of the hepatic artery, and a bile duct. 　　A central vein runs through the middle of the lobe and is surrounded by cords of liver cells that radiate out in all directions. Between these cords are wide thinwalled blood vessels called sinusoids. All of the blood drains into a hepatic vein which then circulates throughout the body.   　　肝的微细结构 　　在显微镜下，肝脏是由肝小叶为单位的网状结构。肝小叶非常小，是六棱柱体。 　　小叶的周围是结缔组织，边缘围绕着5-7串脉管，有门静脉、肝动脉和胆小管。 　　小叶的中央由中央静脉穿过，周围被向四周呈放射状排列的肝细胞索包围。在索之间是扩大了的毛细血管叫血窦。所有的血液都流入肝静脉参与体循环。