Mechanisms Controlling Ovulation of Avian and Mammalian Follicles 127 



The observations presented in these experiments (Tables 2 and 3) led to 

 the postulate that ovulation may be normally a hormone withdrawal 

 phenomenon. To test this possibility further, a comparison was made 

 between ovulability of follicles which were exposed to LH alone, with those 

 which were given LH together with support by a gonadotropic hormone. 

 Since the LH preparation used was known to be heavily contaminated with 



Table 3. Effect of Time on Dose of LH Required to Induce Single or Double 

 Ovulations in Hypophysectomized Hens 



Table 4. Effect of Hormonal Support on the Ovulability of 

 Follicles of Hypophysectomized Hens 



* Weight 0.81 g. 



FSH, and since even small doses of FSH may be sufficient to provide support, 

 it was decided to use the minimum effective dose of LH in order to minimize 

 the FSH effect. Two groups of hens were each injected with 0.5 mg of LH 



