Analysis of the shift of hematopoietic foci

在胎儿DA大鼠肝脏中，造血发生在妊娠第14天至第20天左右，尽管造血细胞数量在第18天达到最大值。出生后，造血病灶大多消失。光镜和电镜形态学分析显示妊娠期造血功能的变化。利用我们建立的抗大鼠胎肝造血细胞单克隆抗体（UB-12）的免疫细胞学和免疫组织学方法对大鼠造血组织的分析是有效的：当胎肝造血活跃时，UB-12检测到的抗原表达广泛，而随着造血功能的减少而平行降低。利用UB-12单克隆抗体和放射免疫分析法，可以半定量地跟踪造血焦点从胎儿肝脏向成人骨髓的转移。造血细胞表面的一些抗原，如细胞粘附分子，在造血细胞间相互作用中起着重要的作用，而UB-12抗原可能就是其中一种。针对成人肝细胞（HAM4和其他）的单克隆抗体检测到的肝细胞抗原表达在妊娠早期为阴性或相当低，在妊娠后期增加。然而，即使在出生前，其表达程度也低于成人水平。胎儿型肝细胞向成体型肝细胞转变过程中所发生的形态学变化在出生时也变得明显，证明胎儿肝细胞与成体肝细胞存在明显差异，提示胎儿肝细胞具有造血细胞的基质功能。此外，旁分泌类型的细胞-细胞相互作用可能对胎儿造血细胞和肝细胞增殖很重要。因此，妊娠第19天后肝脏造血灶的减少可以部分解释为造血细胞与胎儿肝细胞间细胞相互作用的改变，而围产期胎儿全身发生的变化，如骨骼和骨髓形成的开始，以及出生前后内分泌或代谢的变化也可能是重要的

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