| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Kiyoshi Kumamoto Univ. Dept.Pathol.Professor, 医学部, 教授 (70045631)
NISHIKAWA Shinichi Kumamoto Univ. Instit. Immunol. Professor, 医学部, 教授 (60127115)
MORI Kazuhiro Niigata Univ. Dept. Biol. Professor, 理学部, 教授 (90025635)
FUKUMOTO Tetsuo Yamaguchi Univ. Dept. Anat. Professor, 医学部, 教授 (00040171)
OKADA Masukichi Tsukuba Univ. Biol.Sci. Group Professor, 生物科学系, 教授 (60015534)
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| Research Abstract |
The present study deals with germ cell formation and hemopoiesis in vertebrates and in invertebrates for an analysis of cell lineages through development. I. The ancestors of germ cells, the primordial germ cells (PGC); appear at an extragonadal site in an early stage of embryonic development and eventually migrate into the gonadal anlage, where they differentiate into definitive germ cells. II. Hemopoiesis in mammals is initiated in the embryonic yolk sac, continues in the fetal liver and finally in the bone marrow. At all three sites, the hemopoietic stem cells (HSC) and their derivatives at various stages of differentiation to myeloid and lymphatic cells can be observed.
(1) With regard to the origin of PGC, it was shown that, in Drosophila, a cytoplasmic factor, mtlrRNA is necessary to form the pole cell (progenitor of PGC) (M.Okada). In xenopus laevis, an essential component of the "germ plasm" necessary for dete mation of the primitive PGC was examined (A.Ikenishi). In amniotes, t
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he migratory mechanisms and ectopism of PGC were studied (T.Fujimoto). The relationship between the origin of the so-called "germ cell tumor" and ectopic PGC was approached (T.Motoyama).
(2) Regarding hemopoiesis and HSC, hemopoietic processes in the embryonic yolk sac and fetal liver in mice and rats were analyzed in terms of type and distribution pattern of cells which were present and were differentiating there, both morphologically (K.Sasaki) using monoclonal antibodies specific to hepatic hemopoietic cells (T.Fukumoto) and macrophages (K.Takahashi). In in-vitrostudies, analyses of the so-called hemopoietic promoting factors have progressed. Purification of HSC from human blood (T.Suda) and from mouse bone marrow (K.Mori) was performed and their differentiation to various myeloid and lymphatic cells was studied. It was also clarified that B-lymphocyte proliferation is supported and regulated by stromal molecules such as Interleukin 7 (S.I. Nishikawa) . Studies of the migration of T-lympocyte progenitors into the thymus and their differentiation within it were approached in detail (S.Tochinai).
Problems to be solved are: 1. continuity of HSC through three hemopoietic sites as described above, and 2. inhibitory mechanism of PGC differentiation during their migration to the gonadal anlage. Less
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