Hematopoiesis in the liver The liver develops as a hematopoietic organ at the fetal stage in the mammalian liver, prior to bone marrow development [8]. In amphibians, the liver is an immunocompetent organ, and hepatic hematopoiesis is initiated in urodele sites. It is well known that the thymus,

spleen and liver are the three primary sites of hematopoiesis in the adult newt [5, 7, 22]. Pictilisib Previous investigations indicate that the thymus is https://www.selleckchem.com/products/wortmannin.html lymphopoietic, the spleen is lymphopoietic thrombopoietic and erythropoietic [23, 24], and the liver is granulopoietic with small lymphocyte-like cells in the perihepatic subcapsular region (PSR) which might be granulocyte precursors [7, 23]. The newt liver possesses immunologic capabilities due to the presence of lymphocytes in the PSR of the liver [4]. This study has shown LY333531 cost that the hematopoietic tissue structures of amphibian livers were observed in three regions: (a) the perihepatic subcapsular region (PSR), (b) portal triads region (PTR), and (c) inter-hepatic lobular nodule. Our study of 46 species showed that hematopoietic tissue structures were observed in both PSR and PTR in both Caudata and Gymnophiona orders, but in the order Anura, hematopoietic tissue was not observed in

either PSR or PTR. Inter-hepatic lobular nodules were observed in all amphibian livers. In this study, we revealed that anuran livers did not have hematopoietic tissue structures, as did mammal liver. In contrast, urodele and caecilian livers had hematopoietic tissue structures with hepatic initial sites of hematopoiesis. Conclusions This study showed that the architecture of the parenchymal arrangement was related to phylogenetic relationships, but hematopoiesis may not occur phylogenically. We suggested that hematopoietic tissue structures were concerned with the development in bone marrow and spleen of the systemic Fossariinae immune system. In hepatic ontogenesis, we demonstrated that the parenchymal arrangement is formed phylogenically.

Acknowledgements We thank Mr. Hiroyoshi Kohno and Mr. Ken Sakihara, Okinawa Regional Research Center, Tokai University, for their help in this study. We thank Mr. Kouji Tatewaki, and also thank Mr. Hiroyuki Fujita, Hyogo University of Teacher Education for help in sample collection. References 1. Rappaport AM: Diseases of the Liver. In Anatomic considerations. Second Edition edition. Edited by: Schiff L. Philadelphia: Asian Edition Hakko Company Limited; 1967:1–46. 2. Elias H, Bengelsdorf H: The structure of the liver of vertebrates. Acta Anat 1952, 14:297–337.PubMedCrossRef 3. Akiyoshi H, Inoue A: Comparative histological study of teleost livers in relation to phylogeny. Zool Sci 2004, 21:841–850.PubMedCrossRef 4. Rubens LN, Van der Hoven A, Dutton RW: Cellular cooperation in hapten-carrier responses in the newt, Triturus viridescens. Cell Immunol 1973, 6:300–314.CrossRef 5.