146 PRACTICAL MICROSCOPY. 



brana propria. (This is difficult to separate from the stroma of the 

 ovary itself, except in more mature follicles than shown in the sec- 

 tion.) (c) The membrana granulosa. (This, in general, appears 

 to be the outer layer of the follicle, on account of the difficulty of 

 separating the membrana propria from the stroma proper of the 

 ovary. Note that it is composed, in the smaller and less mature fol- 

 licles, of pavement cells, and that the cells become thicker with matu- 

 ration, until columnar cells in single layer result.) (d) The ova. 

 '(These are contained within the follicles, excepting they may have 

 become detached during manipulation of the section, and occupy the 

 :greater area of the same.) (e) The zona pellucida (the thin wall of 

 the ovum). (/) The discus proligerus. (This will be recognized 

 ;as a mass of polyhedral cells, connecting the ova at one side with the 

 columnar cells of the membrana granulosa. These cells will prolif- 

 erate later in the development, and completely inclose the ovum.) 

 (g) The germinal vesicle. (Contained within the ovum. The con- 

 tents appear granular; it, as well as the ovum, is fibrillated; but this 

 demonstration cannot be made excepting the animal be killed for the 

 purpose, and the tissue elements fixed before changes, which quickly 

 follow death, occur.) (h) The germinal spot. (Appearing as a 

 small dot within the germinal vesicle. The ovum presents the char- 

 acteristics of what it indeed is a typical cell, with wall, body, nucleus, 

 and nucleolus. ) 



5. The corpus luteum. (The example shown in the drawing, as 

 I have already said, was developed after the contents of the Graafian 

 follicle, which it represents, had suffered impregnation; and it has 

 arrived at the later stage of the series of phenomena connected with 

 its development the stage of cicatrization. The cicatricial tissue, to 

 which the letter K points, indicates the remains of the membrana 

 granulosa. Outside is seen the thickened membrana propria, while 

 among the contents will be found pigment granules and fat globules, 

 imbedded in a structureless, gelatinous stroma. This material results 

 from changes in the clot of blood effused after the escape of the 

 ovum. I do not tabulate these elements, as it is extremely improb- 

 able that the student will find a corpus luteum in precisely the condi- 

 tion of the one represented until he has examined a large number of 

 specimens. ) 



