402 THE CORPUS LUTEUM OF DASVrRrS, 



most cells set upon a distinct membrana propria or basal membrane. 

 Immediately outside {i.e., below) the membrana propria is seen the theca 

 folliculi, and this figure shows the most extreme specialisation of theca 

 folliculi into theca interna and theca externa found in Dasyurus. Small 

 blood vessels are seen in the theca, and the characters of the two parts of the 

 theca are to be distinguished. The lower part of the figure is occupied by 

 cells of the young corpus luteum. In one place is illustrated the tendency 

 for the theca interna to send in a process of itself towards the central cavity 

 of the corpus luteum (not shown in the figure but placed below). On either 

 side of this process the basal membrane is still fairly distinct, and the 

 metamorphosis of the cells of the former membrana granulosa into those of 

 the corpus luteum is just commencing. 



Fig. 8. — Portion of a section from ovary, Stage B ( x 80). 



This section was taken through a newly ruptured follicle, but the plane of 

 section does not go through the site of rupture. It shows the corrugation 

 of the membrana granulosa and the dilatation of the blood vessels of the 

 theca, which are pushing portions of the membrana granulosa towards the 

 cavity, in which some remnants of coagulum are left. 



Plate X. 



Fig. 9. — From same ovary, Stage B ( x SO). 



Shows the freshly ruptured follicle, which has been closed. The site of 

 rupture is easily distinguishable and also the plug of cells closing the aperture 

 (Bouchon Epithelial). The membrana granulosa is beginning to thicken. 

 The blood vessels of the theca are seen to be dilated in several places, and in 

 one portion of the follicular wall below and to the left between dilated blood 

 vessels can be seen still the persistent membrana propria. The theca folliculi 

 is seen best on the left hand side of the follicle. 



Fig. 10. — Portion of the wall of an early corpus luteum from ovary. Stage 

 B ( X 350). 



This figure shows a sprout of connective tissue projecting into the mem- 

 brana granulosa. The membrana propria is still seen distinctly in one 

 place. To its left are cells of the membrana granulosa, and to its right the 

 tissues of the theca interna, containing blood vessels filled with red cor- 

 puscles. 



Plate xi. 



Fig. 11.— Section of ovary. Stage C ( x 130). 



This figure is extremely interesting. It shows the filling of the central 

 cavity of the corpus luteum with connective tissue which is irrupting in 

 several places, notably above and to the left.* Numbers of rounde dcells, 

 probably " fibroblasts," are seen in the interior of the follicle, many of them 

 free and others placed in juxtaposition to a strand of connective tissue, 



♦ The right side of the Plate is to be regarded as the top of the tigure. 



