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Biol Bull 114: 226-246. (April 1958)
© 1958 Marine Biological Laboratory
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GASTRULAR BLOCKAGE IN FROGS' EGGS PRODUCED BY OXYGEN POISONING

SASHA MALAMED 1

1 Department of Zoology, Columbia University, New York 27, N. Y.

1. The effect of oxygen poisoning on gastrulation in Rana pipiens eggs has been studied using an apparatus consisting of 6 pressure systems continuous with each other or not, in various combinations. The apparatus permitted the embryos to be kept at constant temperature. Shaking and non-shaking samples could be run simultaneously. Oxygen treatment started before the first cleavage and ended during the early cleavage stages.

2. In the mechanical sense, pressure has no effect on gastrulation, for gastrulation is normal in experiments using nitrogen and in others using oxygen without shaking.

3. The role of pressure is via an increase in the oxygen tension of the eggs' medium, according to Dalton's Law. That gastrular blockage is a function of oxygen tension is shown by comparing results with and without shaking for various durations of treatment and by the higher percentage of abnormal gastrulae with higher partial pressure of oxygen.

4. With shaking and 45 p.s.i. of oxygen added to air at 1 atmosphere, durations of treatment of less than 8 hours are without effect on gastrulation. At this threshold, additional treatment of about 4 hours results in no normal gastrulae.

5. Temperature has little if any (net) effect on oxygen poisoning. This is explained on the basis of several temperature effects which are largely compensatory.

6. With 2.2 atmospheres partial pressure of oxygen a longer duration of treat ment is required to affect gastrulation than with 3.2 atmospheres. An effect has been obtained using 1.2 atmospheres.

7. Comparison with controls shows that after oxygen treatment the embryos are not always retarded before gastrulation. When there is a developmental delay, it is slight and does not begin before the late blastula stage.

8. These results are interpreted as follows: at gastrulation a qualitative change occurs such that a new chemical system on which development is dependent comes into play. During early cleavage high oxygen concentrations inhibit either this system or conditions necessary for its establishment.






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Copyright © 1958 by the Marine Biological Laboratory.