The formation of the mesoderm in urodelean amphibians
Dorsal (D), lateral (L and R), and ventral (V) portions of the endoderm of blastulae ofAmbystoma mexicanum of different age (stages 8+ to 10−) were combined with ectodermal caps of stage 8+ blastulae. All V and most L and R portions induced only ventrocaudal mesodermal structures — “ventral” type of mesoderm induction. Almost all D portions induced much more voluminous structures of predominantly axial character — “dorsal” type of mesoderm induction. The difference in mesoderm-inducing capacity of the dorsal as against the lateral and ventral endoderm is probably purely quantitative in character. The dorsal endoderm exhibits a pronounced dominance in mesoderm-inducing capacity. During the early symmetrization of the amphibian egg it is apparently especially the presumptive dorsal endoderm that becomes endowed with strong mesoderm-inducing properties.
A comparison of the results obtained with endodermal portions of blastulae of different age showed that the mesoderm-inducing capacity first begins to decline in the dorsal endoderm (around stage 9), subsequently in the lateral, and finally in the ventral endoderm (at stage 10−). At stage 10− the dorsal endoderm no longer has mesoderm-inducing capacities.
In the recombinates there is a striking correspondence between the regional differentiation of the mesoderm and that of the endoderm. The latter differs markedly from the presumptive significance of the various endodermal regions in the normal embryo.
Primordial germ cells, which constitute a characteristic component of the “ventral” type of mesoderm induction, can be induced not only by ventral, but also by lateral and to some extent even by dorsal endoderm. The development of primordial germ cells from the ectodermal component of the various recombinates indicates that in the urodeles the origin of the primordial germ cells differs markedly from that in the anurans.
KeywordsRecombinates Germ Cell Developmental Biology Regional Differentiation Primordial Germ Cell
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- Ancel, P., Vintemberger, P.: Recherches sur le déterminisme de la symétrie bilatérale dans l'oeuf des amphibiens. Bull. biol. France Belg., Suppl.31, 1–182 (1948)Google Scholar
- Bounoure, L.: L'origine des cellules reproductrices et le problème de la ligne germinale. Paris: Gauthiers-Villars 1939Google Scholar
- Harrison, R.G.: Harrison stages and description of the normal development of the spotted salamander, Amblystoma punctatum (Linn.). In: Organization and development of the embryo, by R. G. Harrison, ed. by S. Wilens, p. 44–66. New Haven, London: Yale University Press 1969Google Scholar
- Holtfreter, J.: Differenzierungspotenzen isolierter Teile der Urodelengastrula. Wilhelm Roux' Arch. Entwickl.-Mech. Org.138, 522–656 (1938)Google Scholar
- Kraft, A. von: Entstehung der Eingeweide-Asymmetrie bei den Wirbeltieren. Naturw. Rdsch. (Stuttg.)24, 142–151 (1971)Google Scholar
- Nieuwkoop, P.D.: Experimental investigations on the origin and determination of the germ cells, and on the development of the lateral plates and germ ridges in Urodeles. Arch. néerl. Zool.8, 1–205 (1947)Google Scholar
- Nieuwkoop, P.D.: Pattern formation in artificially activated ectoderm (Rana pipiens and Ambystoma punctatum). Develop. Biol.7, 255–279 (1963)Google Scholar
- Nieuwkoop, P.D.: The formation of the mesoderm in urodelean amphibians. I. Induction by the endoderm. Wilhelm Roux' Archiv162, 341–373 (1969a)Google Scholar
- Nieuwkoop, P.D.: The formation of the mesoderm in urodelean amphibians. II. The origin of the dorso-ventral polarity of the mesoderm. Wilhelm Roux' Archiv163, 298–315 (1969b)Google Scholar
- Nieuwkoop, P.D.: The formation of the mesoderm in urodelean amphibians. III. The vegetalizing action of the Li ion. Wilhelm Roux' Archiv166, 105–123 (1970)Google Scholar
- Nieuwkoop, P.D., Ubbels, G.A.: The formation of the mesoderm in urodelean amphibians. IV. Qualitative evidence for the purely “ectodermal” origin of the entire mesoderm and of the pharyngeal endoderm. Wilhelm Roux' Archiv169, 185–199 (1972)Google Scholar
- Nieuwkoop, P.D.: The “organization center” of the amphibian embryo: its origin, spatial organization, and morphogenetic action. Advanc. Morphogenes.10, 1–39 (1973)Google Scholar
- Pasteels, J.J.: The morphogenetic role of the cortex of the amphibian egg. Advanc. Morphogenes.3, 363–388 (1964)Google Scholar
- Sala, M.: The character of the “local activations” formed in sandwich expiants of competent ectoderm containing neural formations induced by different cranio-caudal portions of the archenteron roof. Proc. kon. ned. Akad. Wet. C59, 661–667 (1956)Google Scholar
- Siegel, S.: Nonparametric statistics for the behavioral sciences. New York: McGraw-Hill 1956Google Scholar
- Sudarwati, Sri, Nieuwkoop, P. D.: Mesoderm formation in the anuran Xenopus laevis (Daudin) Wilhelm Roux' Archiv166, 189–204 (1971)Google Scholar
- Vogt, W.: Gestaltungsanalyse am Amphibienkeim mit örtlicher Vitalfärbung. II. Gastrulation und Mesodermbildung bei Urodelen und Anuren. Wilhelm Roux' Archiv Entwickl.-Mech. Org.120, 384–706 (1929)Google Scholar
- Yamada, T.: Dorsalization of the ventral marginal zone of the Triturus gastrula. I. Ammonia-treatment of the medio-ventral marginal zone. Biol. Bull.98, 98–121 (1950)Google Scholar