THE GROWTH OF THE OVUM 35 



follicles do develop to the stage of antrum formation. The 

 absence of eosinophile cells in the pituitaries of dwarf mice 

 may, however, indicate the absence of a necessary link in the 

 chain of steps involved in the hypophysis-gonad relationship. 

 Whatever the effect of ovarian maturation upon the pi- 

 tuitary may be, it is plain that no follicular response to pitui- 

 tary hormones occurs until the time when full sized ova are 

 present. Does this mean that the maturation of the follicle 



120 



iioH 



100 

 ^.90 



^ 80 

 ^ 70 

 O 60 



H 50 

 H 



S 



^ 30 



(a) . / 



(b) 



. OBSERVATIONS 



X CALCULATED POINTS 



100 200 300 400 500 600 700 800 900 1000 



DIAMETER OF FOLLICLE, (jl. 



Fig. 9. Same as Fig. 8. Data on the ferret. (From the Proceedings of the 



Royal Society.) 



is dependent initially upon some influence of the ovum, or 

 is the simultaneous development of the ovum to full size 

 and follicular growth to stimulable size a coincidence only? 

 The ovum may grow to full size without an investiture of 

 follicle cells as attested by the frequent presence of such 

 ova in the ovaries of dwarf mice (Pincus, unpublished data). 

 On the other hand, anovular follicles do occur in mammalian 

 ovaries (League and Hartman, 1925) though those of large 

 size represent follicles with completely resorbed ova (Engle, 

 19276). It is interesting to note also that frequent produc- 

 tion of anovular follicles from the germinal epithelium takes 

 place in senile rats (Hargitt, 1930). 



