Analysis of the shift of hematopoietic foci

在DA胎鼠肝脏中，造血细胞在孕14~20天左右发生，但在第18天达到高峰。出生后，造血灶基本消失。光镜和电子显微镜的形态分析表明，在妊娠期间，造血功能发生了变化。用我们建立的抗大鼠胎肝造血细胞(UB-12)的单抗免疫细胞学和免疫组织学方法分析大鼠的造血组织是有效的：当胎肝造血活跃时，UB-12检测到的抗原表达广泛，但随着造血量的减少而减少。应用UB-12单抗和放射免疫分析技术，可以半定量地追踪造血中心从胎肝向成人骨髓的转移。造血细胞的一些表面抗原，如细胞黏附分子，在造血细胞…之间的细胞-细胞相互作用中起重要作用。更多的LS和基质细胞以及UB-12抗原可能是此类分子之一。用抗成人肝细胞(HAM4等)的单抗检测，妊娠早期肝细胞表面抗原表达呈阴性或极低水平，妊娠后期呈上升趋势。然而，即使在出生之前，这种表达的程度也低于成年人的水平。随着胎儿型肝细胞向成人型肝细胞的转变，其形态变化在出生后也变得明显，证明胎肝细胞与成人肝细胞之间存在明显的差异，提示胎肝细胞对造血细胞的间质作用。此外，旁分泌型细胞-细胞相互作用对胎儿造血细胞和肝细胞的增殖也可能是重要的。因此，妊娠19天后肝脏造血灶的减少部分可以通过造血细胞与胎肝细胞的细胞间相互作用的变化来解释，而围产期胎儿全身发生的变化，如骨骼和骨髓形成的开始，以及出生前后的内分泌或代谢变化，也可能不那么重要。

In the fetal DA rat liver,hematopoiesis occurs around day 14 to day 20 of gestation, although the maximum number of hematopoietic cells are observed on day 18. After birth, the hematopoietic foci mostly disappear. Morphological analysis by light and electron microscopy reveals changes in hematopoiesis during gestation. Immunocytological and immunohistological methods using a monoclonal antibody against rat fetal liver hemato-poietic cells(UB-12)established by us are effective for analysis of rat hematopoietic tissues:The antigenic expressions detected by UB-12 are extensive when hematopoiesis in fetal liver is active,while decreases in parallel with the decrease of hematopoiesis. Using UB-12 monoclonal antibody and radioimmunoassay,it is possible to follow the shift of hematopoietic focus from fetal liver to adult bone marrow semiquantitatively. Some surface antigens of hematopoietic cells such as cell adhesion molecules are important for cell-cell interaction between hematopoietic cel … More ls and stromal cells and UB-12 antigen might be one of such molecules. The expression of antigens on hepatocytes detected with monoclonal antibodies directed against adult hepatocytes(HAM4 and others) is negative or quite low in the early gestational period and increases in later stages. However,even before birth the degree of expression is lower than the adult level. The morphological changes occurring with the transition from fetal-type to adult-type hepatocytes also become obvious towards the birth proving distinct difference between fetal hepatocytes and adult hepatocytes,and suggesting stromal function of fetal hepatocyte for the hematopoietic cells. Also paracrine type of cell-cell interaction may be important for fetal hematopoietic cells and hepatocytes to proliferate. Thus, the diminution of hematopoietic foci in the liver after day 19 of gestation can be explained partly by changes in the cell-cell interaction of hematopoietic cells with fetal hepatocytes,while the changes occurring in the whole body of the fetus in the perinatal period,such as the start of bone and bone marrow formation,and endocrinological or metabolic changes around birth may also be important Less