QUANTITATIVE STUDY ON THE REGIONAL DISTRIBUTION OF PENTOSE NUCLEIC ACID IN THE GASTRULA AND NEURULA OF TRITURUS

Abstract

The distr. of PNA in different areas of the ectoderm and mesoderm of (a) the early gastrula, and (b) the neurula with rising folds, of Triturus pyrrhogaster was estimated, using the technique of Schneider, and expressed in [mu]g. of phosphorus/mg. nitrogen. In both stages, values for ectodermal regions were found to be consistently higher than those for mesodermal regions. Higher values for the neurula in all regions indicate a general rise of PNA during gastrulation. The highest values in the gastrula were found in the prospective neural ectoderm and not in the mesoderm. The latter shows a dorso-ventral gradient in the marginal zone. In the neurula, the neural plate shows the highest value of all regions. The gradient within the mesoderm seems to have disappeared.