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DISCUSSION 



Wislocki: I should like to ask Prof. Harrison whether, besides the 

 chorioallantoic placenta, he also investigated potassium transfer through 

 the yolk-sac placenta, and what differences he found ? 



Harrison: We made a few estimations of that. The uptake after 

 15 minutes and one hour were negligible. The uptake was so small that 

 it was not significant in comparison with the uptake of other parts of 

 the placenta. And that frankly did surprise us. I would have expected 

 that there would be considerable uptake, but there was not — but that 

 was not near term and it may be that that is relevant to Prof. Dempsey's 

 comments earlier on. 



Hnggett: There are two points. First, Cloette observed in the 

 placentomes in sheep and goats the change in cup-shaped to the flattened 

 type, and I would rather associate it with age ; that at full-term or post- 

 partum there is a preponderance of the flattened placentomes, but at 

 mid-pregnancy or earlier you would have these cup -shaped. I have not 

 worried very seriously about the matter. 



The second point is, Dr. Seoras Morrison has been working with me 

 during the last few months on the uptake of [ 14 C] glucose, given to the 

 mother, by glycogen in the rabbit placenta and there we find quite 

 definite differences between the decidual glycogen and the chorionic 

 glycogen. They do not behave in the same way. I was also very 

 interested in the general finding you had that the placenta compared 

 with the liver has a very latent active uptake — I hope I may use that term. 



Harrison: Yes — the cup-shaped placentomes have a potassium con- 

 tent and an uptake of radioactive potassium equivalent to that in the 

 flattened placentomes. Both liver and placentome are rich in potassium, 

 but the uptake of radioactive potassium by the placentome is not as 

 great, therefore one thinks of differences in the blood supply, and the 

 rate of flow and thus the opportunity for exchange. 



