CONCRESCENCE OF FOLLICLES IN HYPOTYPICAL OVARY. 1 93 



of interest to inquire whether in all cases the causes are the same, 

 or whether different conditions may lead to the same result; 

 In such an inquiry we have to keep in mind the possibility that 

 a hypotypical condition of the ovaries might be a transitory 

 state; that after having led to the production of follicles with 

 multiple eggs, new follicles may again begin to develop normally, 

 so that in the end nothing indicates that at one time such 

 ovaries had been hypotypical. 



This concrescence of follicles is somewhat analogous to a condi- 

 tion we find in other glands. In the thyroid of the guinea pig, 

 as well as in the mammary gland of the mouse, we found occa- 

 sionally structures which could only be explained as due to a 

 concrescence of neighboring acini; due to the disappearance of 

 the walls separating adjoining acini. We have therefore to deal 

 with a phenomenon of a more general character, which under 

 certain conditions may perhaps occur in all the glands. 



There was in the ovaries of this guinea pig an additional 

 feature which deserves special mention, viz., the very marked 

 development of what corresponds to the interstitial gland in 

 the rabbit. As we stated above, by far the greater part of this 

 ovary consists of follicles in the last stage of atresia, follicles in 

 which the shrunken cells of a well-developed theca interna sur- 

 round one or several small cavities, the remnants of what were 

 formerly follicular cavities. While we find in all hypotypical 

 ovaries a relative preponderance of this kind of follicle, in the 

 ovaries of this guinea pig this feature was more prominent than 

 in the ovaries of the other animals. This is due to the following 

 factors: (i) At the time of the thyroidectomy, the ovaries were 

 in all probability relatively large, the animal weighing at that 

 time 475 grams; thus space was available for the expansion of 

 atretic follicles. (2) The follicles ceased to develop to medium 

 or large size. Thus the pressure exerted by the larger follicles 

 was eliminated, and a chance was given the atretic follicles to 

 occupy the space otherwise occupied by large follicles. The 

 slight development of fibrous bands around the follicles must 

 have a similar effect diminishing pressure exerted on atretic 

 follicles. We may therefore conclude that the structure anal- 

 ogous to the interstitial gland is prominent whenever the intra- 



