Discussions 



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Dr. MnuAM Simpson: As estrogens will cause follicular growth in hypophysectomized rats 

 I think it is quite possible the follicular growth resulting from the combination of 

 FSH and estrogen might be greater than that which results from either alone. 



Dr. FrederickL.Hisaw: I should like to suggest that probably the frog's ovary could be used 

 to test certain ideas that have been mentioned regarding ovulation. One advantage 

 offered is that ovarian fragments can be induced to ovulate quite easily in vitro. Also, 

 sufficient material for a rather large series of experiments can be obtained from a 

 single ovary. Several investigators have reported results of experiments of this sort 

 and the chief difficulty encountered seems to be variability in responsiveness of ovaries 

 from different animals. This is at least partly due to such things as the time of year 

 the frogs are collected and the conditions under which they are kept. Best results can 

 be expected when the animals are taken directly from hibernation under natural 

 conditions. Also, the responsiveness of the ovaries can be greatly increased by admini- 

 stering a subovulatory dose of frog pituitary tissue or by hypophysectomizing the 

 animal a day or so before the ovaries are removed. It may also be added that physio- 

 logical solutions used should be low or even lacking in calcium. 



