Discussions 51 



Dr. Gregory Pincus: That is a probable explanation in the 90-day-olds, and perhaps in 

 the 30-day-old animals, although you would know, perhaps, better than I, whether 

 you would get ovulation in a 30-day-rat. 



There is one possibility that we are examining and that is the possibility that there 

 is in the young rat perhaps some initial stimulation by steroid; I don't think it is true, 

 though, because the ovaries, as you well know, even after two weeks' treatment, are 

 smaller than those of the controls and though there are corpora lutea, they are less 

 in number. 



Also we have run the animals for a longer period of time, and eventually we see no 

 corpora lutea. So I was merely being over-conservative in saying that there may have 

 been an ovulation. Actually, we have no proof. 



In the mouse, we have looked for ova, and it is quite clear that the ova are not 

 produced. Maybe I should have made that remark in my presentation. Otherwise, I quite 

 agree with you that these are just as potent gonadotropin inhibitors in the rat and 

 mouse, by the standards that we have been able to set up, as they are in the rabbit and 

 the human. 



Dr. Ernest Knobil : May I ask Dr. Hisaw whether he has failed to find estrogen in any 

 of these invertebrate animals he has investigated ? 



Dr. Frederick L. Hisaw: So far we have studied ovarian material from only three species 

 of invertebrates: a starfish {Pisaster ochraceous), a sea-urchin {Strongylocentrotus 

 franciscamis) and a pecten {Pecten hericins). Estradiol-17p and progesterone were 

 present in all three, as determined by techniques commonly employed in the isolation 

 and identification of these steroids in mammalian tissue. Lots of 10 to 14 kg of ripe 

 ovaries were extracted. The amounts of these steroids on a tissue-weight basis were 

 very small and we were interested primarily at this time in identification rather than 

 quantitation. However, the estrogen content in pecten ovaries was found to be much 

 greater than in the ovaries of either the starfish or sea-urchin. 



Dr. Janet McArthur : I would like to ask Dr. Simpson what sort of extrapolation she 

 would make from these studies to her applied work on the FSH and ICSH content 

 of the monkey pituitary during diff"erent stages of the menstrual cycle. 



Dr. Miriam E. Simpson : I do not think we are in a position to answer your question. I made 

 the point for the rat, that we have not so far been able to show a relationship between 

 the pituitary hormone content at different stages of the cycle and the ability to induce 

 ovulation. The preparations of rat pituitary used were crude preparations. 



Such studies have not been conducted with monkey pituitaries removed at different 

 stages of the menstrual cycle. 



Dr. Janet McArthur: In your monkey studies, the FSH went up as well as the LH in 

 the cycle ? 



Dr. Miriam E. Simpson : There are several things that would indicate that the presence of 

 ICSH is necessary for ovulation. The stimulation from FSH preparation may in part 

 be attributable to a masked ICSH in FSH preparations. ICSH cannot be recognized 

 at as low doses in the presence of FSH as when given alone. 



When very high doses of ICSH were injected during preparation of follicles prema- 

 ture thecal luteinization with enclosure of eggs occurred. 



Chairman Creep: The ovulatory process may really start with the growth of the follicle. 

 Perhaps the processes producing ovulation have to follow a given sequence right 

 from the very beginning. Do you see what I am driving at ? 



Dr. Miriam E. Simpson : They have to go on in a normal sequence. 



Chairman Creep: This, we haven't unravelled as yet, but your data indicate to me that if 

 you had a pure FSH, you might not be able to ovulate the follicle when it was fully 

 grown, because certain of the processes had lagged behind, and could not then catch up. 



