Transplantationsversuche zur Frage der Spezifität und der Bildung der Keimblätter

Neural crest and the origin of species‐specific pattern

“…By controlling size and shape throughout the development of these systems, the neural crest underlies the structural and functional integration of the craniofacial complex during evolution. Century, embryologists such as Born (1896), Harrison (1898Harrison ( , 1903, and Spemann (1918) pioneered the use of chimeras, that is combining embryonic components from distinct animal species, to follow the movements and fates of cells, and understand the inductive properties of tissues (Harrison, 1935;Mangold, 1923;Mangold & Seidel, 1927;Noden, 1984;Spemann, 1938;Spemann & Mangold, 1924). Their reliance on intrinsic differences in the number, distribution, and color of intracellular pigment granules as a means to keep track of donor versus host tissues was actually a proxy for a neural crest-derived lineage (i.e., melanocytes), something which was suggested by Harrison (1910) and others but which remained debatable at the time (Dorris, 1938;DuShane, 1934DuShane, , 1935DuShane, , 1938DuShane, , 1939Harrison, 1969;Holtfreter, 1933;Raven, 1931).…”

Proteoglycans with affinity for the neuralizing factor and the vegetalizing factor (activin A homologue)

“…The total amount of protein in a test fraction was 2.0-2.5 rag, ,/-globulin which has no inducing activity was added when necessary. The inducing activity of the fractions was tested by the implantation method on early gastrulae of Triturus alpestris (Mangold 1923). The embryos were cultured as described (Tiedemann 1986), inspected under the dissection microscope and fixed in Bouin solution.…”

Neural inducing factors from Xenopus laevis eggs and embryos

“…Fractions for the Einstecktest (Mangold 1923) were taken up in 6 mol/L urea, 4 mmol/L MgCl2 dialyzed overnight against distilled water, precipitated with ethanol/ether (1:1) and a pellet prepared for implantation as described (Janeczek et al 1984 …”

“…The RNP-particles from eggs and from gastrulaneurula stages of Xenopus laevis were tested by the Einsteckmethode (Mangold 1923 (Plessow et al 1990). Intrachain disulfide bonds of monomers can, on the other hand, be almost completely restored after removal of the reducing agent (Epstein et al 1963 …”