title: Quantification and localization of erythropoietin-receptor-expressing cells in the liver of Xenopus laevis.
abstract: Erythropoiesis occurs in the African clawed frog, Xenopus laevis and is mediated by erythropoietin (xlEPO), a primary regulator of this process. Previously, we have shown that the xlEPO receptor (xlEPOR), which is expressed by erythroid progenitors that respond to xlEPO, is found predominantly in the liver. The aim of the present study was to determine the dynamics of erythropoiesis in the livers of normal and anemic X. laevis by identifying the number and precise location of mature and immature erythrocytes. We quantified mature and immature erythrocyte numbers by o-dianisidine staining or immunohistochemistry and investigated the dynamics of erythropoiesis in normal, acute hemolytic and blood-loss states by in vivo cell proliferation assays with 5-bromo-2'-deoxyuridine (BrdU). We detected 0.12×10(8) xlEPOR(+) BrdU(+) cells in the liver of the normal X. laevis at 24 h after BrdU injection. Frogs presenting with acute hemolytic anemia and pancytopenia show a 10-fold increase in the number of xlEPOR(+)/BrdU(+) cells (approximately 1.30×10(8) cells) in the liver. The xlEPOR(+) cells are found predominantly on the inner wall of hepatic sinusoids. Hematopoietic progenitors that undergo slow cell cycling were also observed in the hepatic sinusoids. This study clarifies the rate of production of mature and immature erythrocytes per day in the liver of X. laevis and the way that these cell numbers change in response to anemia.
authors: Department of Integrative Bioscience and Biomedical Engineering, Graduate School of Advanced Science and Engineering, Center for Advanced Life and Medical Science, Waseda University, TWIns Building, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan.
authors: Takehito
authors: T
authors: Okui
authors: Yusuke
authors: Y
authors: Yamamoto
authors: Shun
authors: S
authors: Maekawa
authors: Kazumichi
authors: K
authors: Nagasawa
authors: Yuka
authors: Y
authors: Yonezuka
authors: Youichi
authors: Y
authors: Aizawa
authors: Takashi
authors: T
authors: Kato
mesh_terms: D000740:Anemia / Q000378:metabolism*; D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D049109:Cell Proliferation; D004906:Erythrocyte Count; D004912:Erythrocytes / Q000166:cytology; D004920:Erythropoiesis / Q000502:physiology*; D004921:Erythropoietin / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D017467:Receptors, Erythropoietin / Q000096:biosynthesis / Q000378:metabolism*; D014982:Xenopus laevis / Q000502:physiology*
chemical_list: D017467:Receptors, Erythropoietin; D004921:Erythropoietin; D001973:Bromodeoxyuridine