title: Studies on the formation and state of determination of the trunk organizer in the newt,Cynops pyrrhogaster.
abstract: The exact localization of the presumptive trunk organizer was determined by means of vital staining at the initiation of gastrulation (0 h embryo) and subsequently in 6, 9, 12 and 24 h embryos.The progressive changes in the self-differentiation and inductive capacity of the trunk organizer were studied in isolation cultures (sitting drop) and in sandwich cultures with competent gastrula ectoderm. In the 0 and 6 h embryo cultures the excised trunk organizer predominantly formed atypical ectoderm. A dramatic change in differentiation and inductive capacity occurred in the 9 h embryo. The positive cases - 83% of the isolation and 50% of the sandwich cultures - mainly formed notochord and somites, accompanied by spinal cord and hindbrain in the sandwich cultures. Although no further change in self-differentiation occurred from that time onwards, a gradual increase in inductive capacity was recognized.
authors.affiliation: Biological Institute, Faculty of Science, Nagoya University, Furo-cho, Chikusa-ku, 464, Nagoya, Japan.
authors.forename: Teruo
authors.initials: T
authors.lastname: Kanéda
authors.affiliation: Biological Institute, Faculty of Science, Nagoya University, Furo-cho, Chikusa-ku, 464, Nagoya, Japan.
authors.forename: Tadao
authors.initials: T
authors.lastname: Hama
keywords: Cynops pyrrhogaster; Mesoderm formation; Morphogenetic movement; Trunk organizer