BY F. P. SANDES. 403 



which stretches across the cavity of the young corpus luteum. The thicken- 

 ing of the former membrana granulosa by hypertrophy of its cells is beginning, 

 and in places, especially on the left of the section, the former relation of 

 theca, basal membrane, and membrana granulosa still persists. The lobu- 

 lated character of the young corpus luteum is also very apparent. 



Plate xii. 



Fig. 12. — From ovary. Stage D ( x 40). 



A slightly later stage of the corpus luteum. The cavity is practically 

 filled with young connective tissue. 



Fig. 13. — From ovary, Stage E ( x 50). 



Shows corpus luteum at later stage still. By this time the cells of the mem- 

 brana have undergone part of their metamorphosis, and have extended 

 further into the cavity. Blood vessels are also seen working their way in 

 between the cells of the corpus luteum; the lower part of the cavity shows 

 some blood vessels streaming in towards the centre of the cavity, whilst 

 above are seen, in between the loosely arranged cells of the corpus luteum, 

 larger venous sinuses filled with blood. 



Plate xiii. 



Fig. 14:. — From ovary, Stage F ( x 50). 



Shows a slightly later stage than tig. 13. The centre of the corpus luteum 

 is tilled with connective tissue, and the blood vessels have also reached the 

 centre. The corpus luteum cells have by this time assumed more definite 

 characters, but have not yet filled the central cavity. 



Fig. 15. — From ovary, Stage G ( x 130). 



Showing the characters of the cells of the corpus luteum. Piunning up 

 the centre of the figure is a connective tissue ingrowth, and on each side 

 cells of corpus luteum. Between many of the cells are seen intervals which 

 are vascular spaces lined by endothelium. 



Plate xiv. 



Fig. 16 — From ovary, Stage H, showing characters of cells of fully formed 

 corpus luteum ( x 500). 



Darkly stained nuclei of connective tissue are seen in various places; and 

 in the centre of the figure an elongated vascular space, immediately against 

 which on the left are placed the characteristic cells of the corpus luteum. 

 The nuclei and nucleoli of individual cells are to be made out, and the cell 

 boundaries are in some cases fairly distinct. 



Plate XV. 



Fig. 17.— Section of ovary, Stage H (low magnitication). Five fully 

 developed corpora lutea are shown. The ovarian stroma is scanty and 



