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

¹ Biological Institute, Science Faculty, Nagoya University, Nagoya, Japan

1. PNA content of prospective regions of the ectoderm and mesoderm of the early gastrula and neurula of Triturus pyrrhogaster was estimated by the technique of Schneider (1945) and expressed in microgram phosphorus per mg. nitrogen.

2. At both developmental stages PNA content was higher in the ectodermal regions than in the mesodermal regions. During gastrulation, an increase in PNA amount was noticed for most of the regions studied.

3. In the gastrula the highest amount of PNA was found in the ectoderm (prospective neural plate) but not in the organizer region. In the marginal zone the dorsal region showed an amount higher than that of the lateral and ventral marginal zones.

4. In the neurula the neural plate showed the highest value. The main part of the archenteric roof contained less PNA than the epidermis. No significant difference could be detected between the values of the archenteric roof and the rest of the mesoderm.