BY F. P. SANDES. 377 



Coiucidently with these processes in the memhrana granulosa, 

 certain clianges go on in the theca folliciili and tlie basal mem- 

 brane. This latter is corrugated, but at first remains intact. 

 The blood vessels of the theca dilate, either as a cause or an 

 effect of the follicular rupture, and occupy the corrugations of 

 the follicular epithelium and membrana propria. The blood 

 supply increases, the cavity of the closed follicle shrinks, and the 

 ovary begins the formation of its corpus luteum. 



The Early Corpus Luteum. 



In the consideration of the disputed question of the origin of 

 the corpus luteum, the crucial period of time is when the consti- 

 tuent parts of the wall of the closed follicle undergo their 

 transformation to formthe component parts of the corpus luteum. 

 It is, therefore, necessary to study these changes in detail. This 

 description is founded upon the appearances of the earl}^ corpus 

 luteum, at the Polar-body Stage of the ovum, and in the segmen- 

 tation stages up to thirty-two cells, and the unclosed blastodermic 

 vesicle, corresponding to Stages B, C and D previously indicated. 

 The period of time occupied by the ovum in passing through these 

 stages is not yet definitely known. 



The three constituents of the follicular wall are aflfected in 

 marked degree, and simultaneously. The event which can be 

 considered to form the turning point in the transition of the 

 follicle into the corpus luteum, is the rui:)ture of the hitherto 

 intact membrana propria. This is effected by the growth 

 inwards of the theca folliculi, which bursts throuoh the membrana 

 propria and sends its connective tissue sprouts towards the cavity 

 of the follicle. The membrana propria becomes indistinct near 

 the apices of these sjDrouts and is lost. Elsewhere it jDersists, 

 and for a comparatively long time can be seen as a homogeneous 

 membrane sharply marking off the theca folliculi from the cells 

 of the former membrana granulosa even after their ti-ansformation 

 into the characteristic cells of the corpus luteum (see fig. 10). 



The connective tissue of the theca folliculi plays a most 

 important part in the formation of the early corpus luteum. 



