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DISCUSSION 



Huggett: The thing that I was interested in is this question of glucose 

 production. It would seem that glucose can be produced metabolically 

 within the placenta, and it would be desirable to distinguish that glucose, 

 if it goes into the foetal blood, from the glucose which is passed from 

 the mother to the foetus. So far as one can see that must be going on 

 right away at full term when the metabolic production of glucose within 

 the placenta ceases. Now the point that interests me there is that in the 

 case of the sheep, where we have been able to study the passage of 

 sugars across the placenta, this passage of glucose from the mother to 

 the foetus can be reversed by reversing the gradient, but it is not in pro- 

 portion to the gradient. The amount that moves is more than can be 

 accounted for by the gradient, and equilibrations do not take place. 

 We have to postulate that there is a cellular activity by the sheep 

 placenta in regard to the passage of that particular monosaccharide. 

 So there are two things — the metabolic production and the trans- 

 mission. I do not know if Dr. Villee would agree with that, but it seems 

 to me a point that we have to keep clear in any analysis. 



Villee: I would certainly agree with that, and I think there is no 

 necessary correlation between the two; they may be quite different 

 processes. When I am speaking of the metabolic production of glucose 

 I am, of course, referring to the production of new glucose molecules 

 from something else, and its actual secretion into the incubation 

 medium where the aliquots are taken. Now the transport of glucose, 

 either into a cell or across or through a cell, may be an entirely different 

 process, one which does not involve the formation of a phosphorylated 

 glucose intermediate. Of course, in the human being as well as in the 

 sheep, glucose is obviously passing across the membrane, and I think 

 it is in part, at least, by some active process though not necessarily one 

 which involves phosphorylation. 



Huggett: The only other point I would emphasize is the interesting 

 finding that there is no difference between normal and toxaemic 

 placentas. That is rather unexpected. 



Villee: You may remember that Hellman was unable to find any 



