title: Inductive interactions required for mesodermal differentiation in Bufo arenarum gastrulae.
abstract: Dorso-marginal epithelium, a distinct crescent-shaped region in the early gastrula of Bufo arenarum, appears after involution as a narrow dorso-median strip of archenteric endoderm close to the notochord. In explant cultures, this layer showed an extreme dorsalizing activity, promoting the formation of notochordal structures from ventro-mesodermal cells. In the presence of ectoderm, this inductive activity was expanded resulting in a wide range of dorso-lateral components such as notochord, muscle, nephric tubules, mesothelium and mesenchyme. The mesodermal origin of these derivatives was confirmed by the use of FDA (fluorescein-dextran-amine)-labelled explants. Extensive mesodermal development in cultures seems to require cell contacts between the inner aspect of the dorso-marginal epithelium and mesodermal cells. When such contacts were prevented, cultures would only differentiate erythrocytes as a result of a purely ectodermal stimulus. Bisection of the dorso-marginal epithelium in whole embryos resulted in the development of a duplicated set of axial structures, clearly showing the role of the epithelium as a dorsal organizer.
authors.affiliation: Cátedra de Histología y Embriología, Facultad de Agronomía y Zootecnia, Universidad Nacional de Tucumán, 4000, Tucumán, Argentina, , , , , , AR.
authors.forename: M E
authors.initials: ME
authors.lastname: Manes
authors.affiliation: Cátedra de Histología y Embriología, Facultad de Agronomía y Zootecnia, Universidad Nacional de Tucumán, 4000, Tucumán, Argentina, , , , , , AR.
authors.forename: Fernando Campos
authors.initials: FC
authors.lastname: Casal
keywords: Key words amphibian morphogenesis; differentiation; dorsalization; mesoderm; organizer