The Role of the Pituitary Gonadotropins 



15 



followed by the usual supplementary dose of the combination excellent 

 ovulation ensued (Table 16). 



Table 16. Supplementary Treatments Effective in Inducing Ovulation, after 



Follicular Development by Purified Sheep FSH and ICSH* Preparations combined 



IN THE Proportion Present in a Rat Pituitary Extract 



ICSH MED 12.5 /^g used with the 25 /xg FSH; MED 1 /^g with all others. 



In order more specifically to define the requirements for the supplement, 

 experiments were conducted to determine whether this proportion and dose 

 of FSH and ICSH (8 RU + 32 RU) was optimal. Each component of the 

 mixture was therefore examined separately, at the dose level contained in 

 the mixture just described (Table 16). It was found that FSH alone at the 

 8 RU level was effective as a supplement under the conditions of this 

 experiment. ICSH was then tried by itself at the same dose at which it had 

 been present in the combined supplement (32 RU) and it too caused ovulation. 

 In some instances, however, the number of animals ovulating and the number 

 of ova shed were less than after the combination or after FSH alone; in fact 

 there was one experiment in which not a single animal ovulated when ICSH 

 only was used as a supplement at the 32 RU level. 



Subsequently the efficacy of ICSH as an ovulatory supplement, following 

 preparation of follicles by 2 RU FSH + 8 RU ICSH, was analyzed more 

 thoroughly at dose levels ranging from 2 to 40 RU. It was found that doses 

 of 16 to 40 RU resulted in ovulation (Table 17). However, when the follicles 

 were prepared by 4 RU of the same purified FSH given alone, and therefore 

 containing only 4 % intrinsic ICSH, even the highest supplementary dose of 

 ICSH (32 RU) was not entirely effective (only 2 of 4 rats ovulated). When 



