Abstract:

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.