CAUSE OF HYPERTROPHY OF SURVIVING OVARY 73 



find very significant differences between these in the semispayed 

 and control rats. In the left surviving ovary (both series I 

 and series II) in which corpora lutea have not yet appeared, 

 that is before puberty, the number of well-developed normal 

 follicles, as well as that of the large degenerate follicles, is con- 

 siderably greater than in the ovaries of the controls, and the 

 same statements hold for the medium-sized degenerate follicles 

 (table 6) . 



In the ovaries of the semispayed rats after puberty there is 

 contained also a larger number of corpora lutea than in the 

 ovaries of the controls. 



The importance of the corpora lutea in determining the weight 

 of the ovary is shown by the case at the sixth week after operation 

 in series I. In this instance, though the ovary of the control 

 has a smaller number of the well-developed and of large degener- 

 ate follicles than the surviving ovary, yet the presence of corpora 

 liitea in the control ovary makes it more than twice as heavy 

 as that of the semispayed. 



So far as my own observations go, therefore, it appears that 

 before puberty the compensatory growth of the surviving ovary 

 is caused principally by the greater number of mature normal 

 follicles, as well as of the degenerate follicles of larger size, prob- 

 ably accompanied by some increase in the stroma. After 

 puberty, on the other hand, the hypertrophy is caused princi- 

 pally by a greater number of corpora lutea in addition to that 

 of the follicles just described. Therefore, since the corpora 

 lutea are relatively large structures, the degree of the hyper- 

 trophy is more conspicuous after puberty than before. 



From the foregoing I consider that Bond was in error when 

 he attributed the hypertrophy of the surviving ovary to the 

 increase of the stroma alone, though this tissue may have some 

 sUght influence. The picture which we have of the compen- 

 satory growth of the surviving ovary is as follows. 



Before puberty there is in the surviving ovary a somewhat 

 more rapid degeneration of ova leading to a shghtly smaller 

 total number. At the same time medium-sized and large follicles 

 are produced ' more rapidly than in the control, and of these a 



