Abstract

Bone marrow is the main hematopoietic organ of mature mammals. Hematopoietic stem cells (HSCs) are maintained in it throughout an organism’s whole life; it also regulates the production of mature blood cells. Adult HSCs are characterized by polypotency, self-renewal, and a specific phenotype, as well as by the ability to direct migration to the hematopoietic organs. The ability of the HSCs to restore hematopoiesis after transplantation into another organism is the main functional criterion for their existence in tissue. However, HSCs, which function in postnatal ontogenesis and possess these properties, represent the final stage of maturation of their precursors (pre-HSCs), which arise in prenatal development. In embryogenesis, hematopoiesis occurs in several transitional blood-forming organs: the yolk sac, aorta-gonad-mesonephros (AGM), placenta, and liver. Despite the long history of research on hematopoietic system ontogenesis, the anatomical site of the origination of the first pre-HSCs, which give rise to the definitive HSC line, is still not entirely clear. The review summarizes modern concepts of the features of the hematopoietic cells formed in the yolk sac, AGM, and placenta, and their contribution to embryonic liver colonization and in definitive hematopoiesis. Further study of the mechanisms of HSC formation in embryogenesis is of undoubted importance, not only for an understanding of the fundamental aspects of hematopoietic system functioning but also for improvement in treatment methods for hematological diseases.

中文翻译：

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胚胎发育中造血干细胞的起源

摘要

骨髓是成熟哺乳动物的主要造血器官。造血干细胞（HSC）在整个生物体的整个生命过程中都得到维持；它也调节成熟血细胞的产生。成年HSC的特征是专能，自我更新和特定的表型，以及直接迁移到造血器官的能力。造血干细胞移植到另一生物体内后恢复造血的能力是其在组织中存在的主要功能标准。然而，HSCs在产后本体发育中起作用并具有这些特性，代表了其前体（pre-HSCs）成熟的最后阶段，这是在产前发育中出现的。在胚胎发生过程中，造血作用发生在几个过渡性造血器官中：卵黄囊，主动脉-性腺-中肾（AGM），胎盘，和肝脏。尽管对造血系统本体发育的研究已有很长的历史，但最早的HSCs起源的解剖部位并不能确定HSC系。该综述总结了卵黄囊，AGM和胎盘中形成的造血细胞特征的现代概念，以及它们对胚胎肝定植和确定性造血作用的贡献。毫无疑问，进一步研究HSC形成在胚胎发生中的机制非常重要，这不仅对于了解造血系统功能的基本方面，而且对于改善血液疾病的治疗方法也具有重要意义。产生明确的HSC线的原因，目前仍不完全清楚。该综述总结了卵黄囊，AGM和胎盘中形成的造血细胞特征的现代概念，以及它们对胚胎肝定植和确定性造血作用的贡献。毫无疑问，进一步研究HSC形成在胚胎发生中的机制非常重要，这不仅对于了解造血系统功能的基本方面，而且对于改善血液疾病的治疗方法也具有重要意义。产生明确的HSC线的原因，目前仍不完全清楚。综述总结了卵黄囊，AGM和胎盘中形成的造血细胞特征的现代概念，以及它们对胚胎肝定植和确定性造血作用的贡献。毫无疑问，进一步研究HSC形成在胚胎发生中的机制非常重要，这不仅对于了解造血系统功能的基本方面，而且对于改善血液疾病的治疗方法也具有重要意义。