BY F. P. SANDES. 401 



with yolk granules, and a thick vitelline membrane, outside which are the basal 

 membrane and the theca folliculi. A similar ovum is seen in fig. 3. 



Plate vii. 



Fig. 3.— Section of a primordial follicle from ovary C just before the 

 appearance of the cavity ( x 130). 



Shows the ovum, containing yolk granules, with a thick vitelline mem- 

 brane, and the cells of the membrana granulosa external to the vitelline 

 membrane. Externally to the membrana granulosa again is a very definite 

 basal membrane, and outside that the theca folliculi. A portion of the same 

 follicle is shown under higher magnification in fig. 7. 



Fig. 4. — A Graafian follicle at an intermediate stage of development 

 ( X about 75), 



The ovum is seen in the centre, surrounded by a layer of cells which are 

 attached by retinacula to the membrana granulosa. The basal membrane 

 and theca folliculi can also be made out. 



Plate viii. 



Fig. 5. — Section of ripe follicle from the ovary, Stage A ( x about 40). 



This follicle was ripe as indicated by the maturation spindle in its con- 

 tained ovum. The ovum is seen as an ellipsoidal body placed in the follicle, 

 close to the surface of the ovary, and bound to the membrana granulosa by 

 retinacula of cells. It is surrounded by the discus proligerus. The cavity 

 of the follicle is partially filled with coagulum of the liquor folliculi. The 

 membrana granulosa is shown and the theca externally. 



Fig. 6 shows under high power portion of walls of adjacent ripe follicles 

 (x350). 



This figure and the next indicate well the characters of the theca folliculi. 

 Above and below are the membranae granulosae of the ripe follicles, some of 

 the nuclei being faintly and others darkly stained. Indications of "Epithel- 

 vacuolen " are seen in places. The membranse granulosae are set upon a 

 distinct membrana propria or basal membrane. On the side of the basal 

 membrane, away from the membranes granulosae, there are to be seen 

 darkly stained nuclei of the cells of the theca interna, wJiose rudimentary 

 character is well shown. The rest of the tissue between the membranas 

 propriae is theca externa whose fibrous tissue characteristics are well shown. 

 Two blood vessels, one filled with coagulum and the other with blood 

 corpuscles, are seen in section, and between their overlapping ends is seen a 

 small ovum. 



Plate ix. 



Fig. 7. — Portion of primordial follicle shown in fig. 3 ( x 500). 

 This figure shows at the extreme top a portion of the ovum, and its 

 vitelline membrane. Next comes the membrana granulosa, with its outer- 



