516 



PHYSIOLOGY OF GONADS 



B 



12 3 4 



12 3 4 



12 3 4 5 



Fig. 8.8. Experimental modification of the 4-day cycle in rats. Same key as in Figure 8.7. 

 Progesterone dosage 1.5 mg. per day. Artificial 5-day cycles in D, E, and F indicated by 

 dotted lines and numbering. (From J. W. Everett, Endocrinology, 43, 395, 1948.) 



B 



e NO OVULATION 



j~~r~r~r 



Fig. 8.9. Experiment with persistent-estrous rats. Units of ordinate and abscissa have same 

 meaning as in Figure 8.7. A. Secjuence of "progesterone cycles." Each dose of progesterone 

 (p) is 1.0 mg. Ovulation (x) in about 70 per cent of the cycles. B. Progesterone cycle followed 

 by unsuccessful attempt to induce ovulation by estrogen during the second c-ycle. C . Pseudo- 

 pregnancy maintained by daily iiijoctinn of 1.5 mg. ]irogosteronr. Ovulation induced by 

 estrogen in several such cases. (From .1. \V. Everett, EiKhxTinolojiy. 43, ;5i»9, 194S.) 



ovulation and corpus luteuni loiniatioii were 

 induced by estrogen (Fig. 8.9 1. 



Early attempts to induce luteinization in 

 the guinea pig with estrogen were unsuccess- 

 ful ( Dempsey, 1937; see Fig. 8.5), but iiioiv 

 recently Lipschutz, Iglesias, Bruzzone, 11 u- 

 niercz and Penaranda (1948) have shown by 

 the use of intrasplenic ovarian autografts 



that luteinization is a reguhir feature in ex- 

 periments in which estrogen is administered 

 systcniically. Interestingly enough the im- 

 plantation of estrogen jiellets in or near the 

 ox'ariaii grafts had tlic coiitrai'y effect of 

 pi'cvcnliiig luteinization. 



it was early I'cportcd that rabbits fail to 

 ovulate in response to estrogen injection 



