E-选择素表达与小鼠胎肝发育及造血功能*★

背景：E-选择素作为一种细胞黏附分子在细胞间选择性识别黏附、调节白细胞归巢及渗出和肿瘤细胞转移等方面的作用已有研究报道，但胚肝发育过程中E-选择素的定性定位研究、与胚肝造血功能的关系至今未见报道。 目的：观察小鼠肝脏发育过程中E-选择素的表达与肝细胞、肝血窦内皮形态分化及胎肝造血作用的关系。 方法：取胚胎11.5(E11.5)至出生后15.5 d(P15.5)的小鼠胚胎或胎肝，常规制作石蜡切片，行苏木精-伊红染色及免疫组织化学检测。光学显微镜下观察胎肝的组织结构变化及细胞形态；免疫组织化学方法检测发育各期肝组织内E-选择素表达。 结果与结论：E11.5肝始祖细胞形成团索样结构，其间有窦样间隙，内有散在的造血干细胞；E12.5 d肝始祖细胞开始增殖分化，其后，随着小鼠胎肝的不断发育，肝细胞数量及体积增大，核质比减小，至出生时形成肝小叶结构；窦样间隙由少到多，由宽变窄，窦壁内皮细胞从少量、不连续逐步增殖形成完整的内皮；造血细胞于E12.5开始造血，E13.5~E15.5达高峰，之后造血功能均逐步减弱。E-选择素表达于E11.5~E15.5胎肝的内皮细胞，定位于内皮细胞的胞膜，随内皮细胞发育及肝细胞分化成熟，E-选择素表达渐消失。提示E12.5~E15.5为小鼠胎肝各细胞发育分化的关键时期，E-选择素表达于此阶段的血窦内皮，与肝脏造血及肝细胞分化有密切关系。

The relationship between the the expressions of E-selectin and the embryonic development as well as hematopoiesis of the mouse liver

BACKGROUND: There are reports concerning effects of E-Selectin, a cellular adhesion molecule, on selectively adhesion among cells, regulation of leukocyte homing and exudation, and tumor cell transfer. However, there are no reports addressing E-Selectin qualitation and positioning study, as well as relationship with embryonic liver hematopoietic function during embryonic liver development. OBJECTIVE: To study the relationship between the E-selectin expression and the morphodifferentiation of the hepatic cells, the sinusoids endothelium as well as hematopoiesis during the embryonic development of mouse liver. METHODS: The mouse fetuses or fetal liver tissues from embryo day 11.5 (E11.5) to postnatal day 15.5 (P15.5) were dissected, fixed and embedded in paraffin. The sections were stained with hematoxylin and eosin and subjected to immunohistochemistry. The development of liver structure and the morphology of cells were observed under an optical microscope. The immunohistochemistry was taken to investigate the expression and localization of E-selectin in fetal livers at different developmental stages. RESULTS AND CONCLUSION: The progenitor liver cells gathered to form the hepatic parenchymal cords at E11.5. The hepatic parenchymal cords were separated by sinusoids with sporadic haemopoietic stem cells in it. The progenitor liver cells began to proliferate and differentiate at E12.5. From then on, the parenchymal cells increased, the volume of the hepatocytes became larger and the karyoplasmic ratio was decreased. The hepatic lobules were formed at natal time. The lacuna of the hepatic sinusoid became narrower and the endothelial cells grown to contiguous. At E12.5, the hematopoietic cells began its hematogenesis and reached its peak at E13.5-E15.5, and then both the blood-forming tissue and hematogenesis decreased gradually. E-Selectin expressed in the membrane of the endothelial cells from E11.5 to E15.5, located in endothelial cell membrane, and disappeared gradually along with the development of endothelial cells and the maturation of the hepatic cells. Above-mentioned results indicated that the most important time for the development of the individual cells in fetus liver is E12.5-E15.5. The expression of E-Selectin was appeared in the sinusoid endothelium, which is associated with the haematogenesis of fetus liver and the differentiation of hepatic cells.