374 THE CORPUS LUTEUM OF DASYrurS, 



TiiK Ripe Graafian Follicle of Dasyuucs vivERRiyirs. 



In determining what constitutes a rij^e follicle in Dasyurus^ 

 one is guided by certain considerations. 



Firstly, when the ovary of a non-pregnant female is examined 

 macroscopically during the oestral period, the follicles which are 

 ripe, or nearly so, are easily perceptible as prominent projections 

 on the surface. They may be as many as twelve to fifteen in 

 number. Microscopically, these projections are found to be due 

 to large follicles which occupy the greater part of the section 

 (see fig. 5), the larger vessels being placed centrally, and the 

 stroma being diminished to a minimum, whilst in the angle 

 between these large follicles are found young ova and follicles, 

 some of which show signs of atrophy. 



Secondly, from the microscopical characteristics of the ripe 

 follicle, to be describedly presently, it is easy to tell whether it 

 be ripe or nearly so. Sobotta says that the test of a ripe follicle 

 is that the nucleus of the ovum must not be in the resting stage, 

 but must either possess a maturation spindle or be preparing for 

 its formation. This holds good also for Dasyurus. 



A description of the ripe follicle necessitates the following 

 subdivisions : — 



1. Of the ovum. 



2. Of the liquor folliculi. 



3. Of the membrana granulosa. 



4. Of the theca folliculi. 



Firstly : — The ovum (see fig. 5) is ellipsoidal and surrounded 

 by a thick envelope; its detailed description will be published 

 later. It is surrounded by a "discus proligerus," and is placed 

 usually towards the periphery of the follicle, and often near the 

 site of the future rupture. The cells of the discus proligerus are 

 of the same type as the cells of the membrana granulosa to be 

 described presently, and the ovum with its discus is connected 

 with the membrana granulosa by strings of similar cells — the 

 " retinacula." 



