正常骨髓中含有形态尚未分化的干细胞,已可识别的分化和成熟中造血细胞以及结缔组织基质,骨髓就是它们进行自体复制的基地。干细胞群有着不同的层次;(1)多能干细胞,能在适当情况下,产生红、粒、巨核、巨噬和B淋巴细胞等系后续细胞;(2)中间干细胞,能产生上述几种(但非全部)系列的细胞;(3)定向单能干细胞,只能产生红、粒或巨核细胞中的某一种。增生速率、储备大小和分化潜能由限制较小到限制较大的过度,都处在严密调控中,俾使骨髓能针对机体对血细胞的要求,作出相应反应,提供类型合适的细胞,反应期限则是有节制或自限性的(图130-2)。如溶血、化脓性感染和血小板免疫性破坏时,分别需要提高红细胞、白细胞和血小板的生成,通常即由骨髓中红、粒或巨核系统的选择性增生来满足这一要求。基质细胞如成纤维细胞等,看来在这些反应中不起 Normal bone marrow contains morphologically undifferentiated stem cells, recognizable differentiation and maturation of hematopoietic cells and connective tissue matrices, which are the bases for their autologous replication. Stem cell populations have different levels; (1) pluripotent stem cells, which produce, in appropriate cases, subsequent lines of cells such as reds, grains, megakaryocytes, macrophages and B lymphocytes; (2) intermediate stem cells that produce the above But not all) of the series of cells; (3) Oriented pluripotent stem cells that produce only one of the red, granulocytes or megakaryocytes. Proliferation rate, reserve size and differentiation potential from a smaller limit to a larger limit over, are closely under control so that the bone marrow can respond to the body’s requirements for blood cells to respond to provide the appropriate type of cells, the reaction period is Is modest or self-limiting (Figure 130-2). Such as hemolysis, suppurative infection and platelet immunity damage, respectively, the need to improve the formation of red blood cells, white blood cells and platelets, usually from the bone marrow of the red, granulocytes or megakaryocytes selective hyperplasia to meet this requirement. Stromal cells, such as fibroblasts, appear to fail in these reactions