Discussion 175 



the pituitary even if the preparation contains no gonadotrophin and it 

 then comes down to what sort of dose you are giving. Are you giving 

 the dose that has an effect on an adult or on a growing young rat: is 

 your dose level higher than the physiological level? If so, I think it 

 might be possible to depress pituitary function and delay implantation 

 even if there were no gonadotrophin present. 



Huggett: These all cause tremendous growth in the mother. 



Williams: So that you are certainly giving excessive amounts? 



Huggett: We have given doses that cause the mother to grow but 

 what we did not get was any sign of it passing across the placenta or 

 causing the foetus to grow. 



Williams: You never got any delayed implantation with the pure 

 compound however much you gave? 



Huggett: No, that is what Swyer found also. 



Montagna: How certain is it whether the implantation was, in fact, 

 delayed or whether this was something else ? 



Huggett: It is not certain beyond the fact that the sizes of the foetuses 

 fitted delayed implantation and that they appear to be entirely normal 

 if you looked on it as being a 15-day foetus when it ought to be 19. 



Montagna : I asked that question largely because I have been waiting 

 for two days for a chance to bring in skin and finally I am able to do it! 

 If one injects rats with large amounts of ACTH or cortisone there is no 

 effect at all on hair growth if the hair follicles had actually started to 

 grow at the time of treatment. If one starts the injections before the 

 hair follicle itself begins to grow no growth occurs in spite of the applica- 

 tion of stimuli which would normally initiate growth. This is the reason 

 I asked if we are sure that it is due to delayed implantation and not to 

 some other condition. 



Huggett: That is quite a valid point. 



Jost: I should like to recall how complicated the problem of delayed 

 implantation is. Canivenc and Mayer recently observed that burning a 

 limb of a pregnant rat will suffice to induce implantation for a long period. 



Williams: Is it not true that in this burning experiment if you take 

 the adrenal out, there is no delay? 



Jost: I think so, but I am afraid of making the wrong statement. 



Amoroso: It has been suggested that if the adrenals are removed you 

 will get the same results. 



Jost: As far as cortisone is concerned, it is very curious to see to what 

 extent the foetus is protected against cortisone. It is possible to inject 

 into a rat foetus, weighing about 500 mg., 3 mg. of cortisone, and the 

 foetus still develops. If the young newborn is injected with only a small 

 fraction of this dose, it dies very quickly. I wonder whether in Prof. 

 Tuchmann-Duplessis' experiments cortisone did not act chiefly after birth. 



T.-Duplessis: I do not know why the embryo is protected, though I do 

 not think it is as well protected as it would appear to be, because the 

 normal embryonic development is a very autonomous one, and there is 

 a 50-70 per cent fragility amongst cortisone-treated animals. None of 

 them lived longer than 10 to 20 days. So even if we do not see a morpho- 

 logical modification, they are still very sensitive to cortisone. 



