190 



Discussions 



Dr. Roland K. Meykr: 1 shall describe data obtained in my laboratory by Mr. W. F. 

 Strauss. The experiment was based on the publications of H. H. Cole (Am. J. Physiol. 

 119, 704, 1937) who reported mating and fetal development prior to parturition in 

 immature rats treated with pregnant mare serum gonadotropin (PMS). In our experi- 

 ment female rats of the Holt/man strain were injected subcutaneously during the 

 morning of the 30lh day of life with one single dose of 0.4 Cartland-Nelson unit of 

 Gonadogen (The Upjohn Company). Forty-eight hours later one or two females were 

 placed with two adult males. Seventy-two hours after PMS injections, vaginal smears 

 were taken; sperm or a vaginal plug was considered as evidence that mating had 

 occurred. 



He started with 144 female rats but many of these were used for other studies as 

 the experiment progressed. On the basis of the data obtained from this group we 

 predict that in a comparable group of 100 rats, 86 would mate, 81 would have an average 



5 100- 



• INDIVIDUAL ANIMALS 



-o-AVERASE WHEN MORE THAN ONE RAT 

 AUTOPSIEO AT A QIVEN HOUR 



HOURS AFTER OVULATOR WAS INJECTED 



Fig. 1. Number of ova recovered from oviducts of immature hypophysectomized rats 

 injected subcutaneously with a FSH preparation, and intravenously with a preparation 

 containing both FSH and LH activity. 



of 10 implantation sites on the 7th day after ovulation, and 75 would parturate an 

 average of 8.5 young (average gestation 22.5 days). The young mothers would lactate 

 and raise an average of 7.2 young to time of weaning. 



Another group of immature females were treated with PMS as described for the 

 first group, except that they were not allowed to mate. The time of the first and subsequent 

 estrous periods was determined by use of vaginal smears. The first estrous smear after 

 the one associated with vaginal opening occurred at an average of 40 days of life, 

 compared with an average of 43 in untreated control rats. The succeeding cycles in the 

 PMS-treated group were shorter and less variable than in the controls. 



At this time I also would like to discuss a group of data from rats related to 

 superovulation and tubal transport of ova. Although tubal transport is a topic outside 

 the scope of this Conference, it can be an important factor in experiments concerned 

 with the quantitative comparison of the effectiveness of ovulators. In these studies the 

 usual procedure is to count the number of ova recovered from the tubes at a definite 

 time after administration of the ovulator. The data which I will present are taken from 

 the thesis of one of my students. Dr. Rae Whitney (Rae Whitney, Doctor of Philosophy 

 Thesis, University of Wisconsin, 1944). 



