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

肝出血前的血液和体腔单核巨噬细胞：10日龄胎鼠的循环血细胞是来源于卵黄囊血岛的原始红细胞，外周血中可见许多单核细胞。胚胎腹膜腔内也可观察到具有相似超微结构的游离吞噬细胞，其前体细胞不是单核细胞，而是来自卵黄囊或间充质的单核细胞。胎肝清道夫巨噬细胞：12日龄小鼠胚胎肝脏中含有巨噬细胞，内含大的异噬菌体，呈血窦状。巨噬细胞作为清道夫，吞噬来自卵黄囊的原始红细胞和从红细胞中排出的核。清道夫巨噬细胞在有丝分裂中从肝窦迁移到肝索，形成细胞团，命名为红母细胞胰岛。血液中的单个核细胞被认为是肝巨噬细胞的前体。胸腺巨噬细胞：单核细胞与w…在15日龄胚胎胸腺的皮质-髓质交界处，更多的巨噬细胞首先出现在血管周围或非常靠近血管的地方，其中含有吞噬包涵体的细胞最多。胎脾和新生儿骨髓中的吞噬细胞：胎鼠和出生早期小鼠的脾含有两种吞噬细胞：清道夫巨噬细胞和肥大细胞，它们的吞噬活性指向突出的红核、红细胞和死亡的造血细胞。新生儿股骨骨髓腔内含有大量多形性核白细胞，表现为早期细胞变性迹象。不仅是游离的巨噬细胞，而且固定的网状细胞吞噬和消化骨髓造血室中的凋亡的中性粒细胞。脾和骨髓清道夫的起源应该与胎肝中单核细胞的产生有关。较少

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