Mononuclear Phagocyte System In Relation To The Development Of Hemopoietic Tissue Of The Mouse Embryo-Light And Electron Microscopic Studies

肝脏造血前的血液和体腔单核细胞吞噬细胞：10天胎鼠的循环血细胞是来源于卵黄囊血岛的原始成红细胞，外周血中出现许多单核细胞。在胚胎腹腔内也可以观察到具有类似超微结构特征的游离吞噬细胞，这些吞噬细胞的前体不是单核细胞，而是来自卵黄囊或间充质的单核细胞。胎肝中的清道夫巨噬细胞：12天小鼠胚胎的肝脏含有巨噬细胞，在血窦中充满大的异噬体。巨噬细胞作为清道夫，吞噬来自卵黄囊的循环原始成红细胞以及从成红细胞排出的核。在有丝分裂中可以看到清道夫巨噬细胞从血窦迁移到肝索，形成称为成红细胞胰岛的细胞簇。血液单核细胞被认为是肝巨噬细胞的前体细胞。 关于我们 此外，充满吞噬内含物的巨噬细胞首先出现在15天胚胎胸腺的皮质-髓质交界处的血管周围空间或非常靠近血管。胎儿脾脏和新生儿骨髓中的吞噬细胞：胎儿和出生后早期小鼠的脾脏中含有两种吞噬细胞，即清道夫巨噬细胞和肥大细胞，它们的吞噬活性直接针对挤出的红细胞核、红细胞和垂死的造血细胞。新生儿股骨骨髓腔内含有许多多形核白细胞，显示细胞变性的早期迹象。不仅游离巨噬细胞，而且固定网状细胞吞噬和消化骨髓造血区室中的凋亡中性粒细胞。脾和骨髓清道夫的来源应考虑与胎肝单核细胞的产生有关。少

Blood And Coelom Mononuclear Phagocytes Before Liver Hemopioesis : Circulating blood cells of a 10-day fetal mouse are primtive erythroblasts derived from yolk sac blood islands, and many mononuclear cells appar in the periphral blood. Free phagocytes with similar ultrastructural features also can be observed in intraembryonic peritoneal cavities, and the precursors of these phagocytes are not monocytes but mononuclear cells from yolk sac or mesenchyme.Scavenger Macrohages in Fetal Liver : Livers of 12-day mouse embryos contain macrophages laden with large heterophagosomes in sinusoids. Macrophages, as scavengers, engulf circulationg primitive erythroblasts from the yolk sac as well as nuclei expelled from erythroblasts. Scavenger macrophages are seen in mitosis to migrate from sinusoids into hepatic cords, forming cell clusters designated as erythroblastic islets. Blood mononuclear cells are considered to be the precursors of the hepatic macrophages.Thymus Macrophages : Monocytes as w … More ell as macrohages laden with phagocytic inclusions first appear in the perivascular space or very close to blood vessels at the cortico-medullary junction of the 15-day-embryo thymus. The perivascular spaces contain many monocyte-like cells, and candidates of precursors of thymic macrophages are monocytes probably from the fetal liver.Phagocytes In Fetal Spleen And Neonatal Bone Marrow : Spleen in fetal and early postnatal mice contains two kinds of phagocytes, scavenger macrophages and mast cells, and their phagocytotic activity is directed toward extruded erythrocytic nuclei, erythrocytes and dying hemopoietic cells. Neonatal femoral marrow cavity contains many polymorph nuclear leucocyte, showing early signs of cell degeneration. Not only free macrophages but fixed reticular cells engulf and digest apoptotic neutrophils in the hemopoietic compartment of bone marrow. The orign of spleen and bone marrow scavengers should be considered in relation to monocyte producion in the fetal liver. Less