The Role of the Pituitary Gonadotropins 



13 



of the efficacy of rat pituitary preparations it was also kept in mind that 

 species specificity of the pituitary proteins might constitute an important 

 factor in the abihty of the protein hormones to induce ovulation. Saline 

 suspensions of pooled rat anterior pituitaries were tested for ovulatory 

 response in hypophysectomized rats and found to be effective when given 

 even at lower unitage than the sheep preparations (provided, of course, 

 that they were given under the conditions of timing described above which 

 were rigidly maintained in this and all subsequent experiments). 



Table 14. Induction of Ovulation by Saline Suspensions of Rat Anterior Pituitary, 

 UNDER Standard Conditions of Timing 



* Distended oviducts indicating ovulation. 



The 40% ethanol extracts of rat pituitary were likewise effective. The 

 unitage administered was, however, of critical importance in determining 

 whether ovulation resulted. When a dose containing 4 x the minimum dose 

 for follicular stimulation was administered, a dose most nearly comparable 

 therefore to the 4 RU dose of sheep FSH though containing 16 times the 

 minimal dose necessary for interstitial cell stimulation, it proved to be too 

 high for ovulation (Table 15). This dose sometimes caused luteinization of 

 the follicle wall with enclosure of ova even before the supplement of twice 

 the total preparatory dose of the same material was given. When a half or a 

 fourth this preparatory dose was given, containing the equivalent of 2 RU 

 FSH + 8RUICSH or 1 RU FSH + 4 RU ICSH, normal, large follicles 

 developed which ovulated when supplemented as before. 



