Bennet Mills Allen 119 



velopnient. The granulosa cells are the first to show signs of degen- 

 eration, the nucleus drawing up into a small globular homogeneous 

 mass in the center of the cell. The cytoplasm changes in such a man- 

 ner as to become more deeply stained than formerly and the whole 

 cell becomes rounded. This is no doubt the process of chromatolysis 

 described by Flemming, 85. It certainly results in the eventual 

 liquefaction of the cells affected. 



Large numbers of connective tissue elements from the capsule and 

 theca interna penetrate into the follicular cavity. As the granulosa 

 cells degenerate further, the follicular cavity becomes smaller and 

 the capsule, theca interna and theca externa contract, thus encroach- 

 ing upon the follicular cavity until the latter has become greatly re- 

 duced. The above mentioned elements that have migrated into the 

 follicular cavity from the capsule and theca interna persist after the 

 granulosa cells have all disappeared. The cells from the theca in- 

 terna later undergo fatty degeneration and finally disappear, leaving 

 the slender connective tissue cells that had migrated from the capsule; 

 these persist and probably remain to form part of the general stroma 

 tissue, lying between the columns of interstitial cells, whose method 

 of formation will be described later. 



A series of fine connective tissue fibres join the follicular capsule 

 with the theca externa passing rather obliquely between the cells of 

 the theca interna. When the capsule closes in upon the follicular 

 cavity these threads are drawn taut and arrange the cells of the theca 

 interna in radial rows. The whole mass may become laterally com- 

 pressed by the growth of neighboring follicles. In very advanced 

 stages of atresia, when the follicular capsule has become reduced to 

 a crumpled remnant lying in the midst of the cells of the theca in- 

 terna, the latter lose their cell walls and become irregular in shape. 

 In this condition they undergo a process of rapid amitotic division 

 (Plate VII, Fig. 27), the resulting nuclei being much smaller than be- 

 fore this process took place. These will develop into the prominent 

 interstitial cells as seen in later stages. 



6 months' Virgin. — In the ovary of this animal (Text Fig. 5) it is 

 possible to trace out the further development of the interstitial cells. 

 They cease to divide and undergo a process of growth in size both of the 

 nucleus and of the cell body. At this stage^ — just after division has 

 ceased — there occurs a deposition of a substance occurring in the form 

 of small spherules, which stain deeply with haematoxylin. They were 

 found only in this one specimen and are in no wise to be confounded 

 with the very numerous fat granules which now begin to fill the cyto- 

 plasm of these interstitial cells. 



