Garcia-Porrero J A, Manaia A, Jimeno J, Lasky L L, Dieterlen-Lièvre F, Godin I E
Departamiento de Anatomia y Biologia Cellular, Facultad de medicina, Universidad de Cantabria, Santander, Spain.
Dev Comp Immunol. 1998 May-Jun;22(3):303-19. doi: 10.1016/s0145-305x(98)00006-8.
Two hemogenic sites are present in mouse embryos before the onset of fetal liver hemopoiesis. While the yolk sac provides for immediate erythropoiesis, an intraembryonic region encompassing the dorsal aorta produces definitive hematopoietic stem cells, as shown experimentally. At early developmental stages this region, that we named paraaortic splanchnopleura, produces multipotent progenitors. At the time of fetal liver colonisation, the paraaortic splanchnopleura further evolves into aorta, gonads and mesonephros (AGM) and contains progenitors capable of long term multilineage reconstitution. Only then are cytologically identifiable collections of early hemopoietic cells present in various arteries and in the mesentery. The present report focuses on the antigenic characterisation of immature hemopoietic progenitors in order to trace back the intraembryonic precursors at earlier developmental stages. CD34, an antigen expressed by immature progenitors and endothelial cells, labels all potential hemopoietic sites. Markers, supposed to counterstain endothelial cells and spare CD34+ hemopoietic cells, also stain various hemopoietic cells. The meaning of these shared antigenic expressions between cells of the endothelial and hemopoietic lineages in the early embryo is discussed.
在胎肝造血开始之前，小鼠胚胎中存在两个造血位点。卵黄囊可立即进行红细胞生成，而实验表明，一个包含背主动脉的胚胎内区域可产生定型造血干细胞。在早期发育阶段，我们将该区域命名为主动脉旁脏壁中胚层，它可产生多能祖细胞。在胎肝定植时，主动脉旁脏壁中胚层进一步演变为主动脉、性腺和中肾（AGM），并含有能够进行长期多系重建的祖细胞。只有到那时，在各种动脉和肠系膜中才会出现细胞学上可识别的早期造血细胞集合。本报告重点关注未成熟造血祖细胞的抗原特征，以便追溯早期发育阶段的胚胎内前体细胞。CD34是一种由未成熟祖细胞和内皮细胞表达的抗原，可标记所有潜在的造血位点。旨在对内皮细胞进行复染并使CD34+造血细胞不受影响的标志物，也会对各种造血细胞进行染色。本文讨论了早期胚胎中内皮谱系和造血谱系细胞之间这些共同抗原表达的意义。
