STRUCTURE OF THE OVARY GRAAFIAN FOLLICLES. 173 



Mammals, either in the older follicles where it is admitted by 

 Kolliker (59), or in the earlier periods of their formation. As the 

 follicular epithelium lining such simple cavities of the stroma 

 increases with the contained ovum, it constitutes a kind of 

 irritant to the surrounding stroma, in consequence of which an 

 increased degree of vascularity is observable around the larger 

 follicles. The first trace of what subsequently becomes the 

 tunica propria appears in the form of a ring of young con- 

 nective-tissue cells around the epithelial layer. This ring 

 enlarges with the increasing vascularization, and at a later 

 period its external layers become converted into ordinary 

 fibrillar connective tissue, and constitute the tunica fibrosa. 

 The development of the walls of the follicles consequently 

 appears to be immediately connected with the formation of the 

 vessels, and it is easily conceivable that migrating or vagrant 

 colourless cells play a certain part in the process. 



The columnar cells of the follicular epithelium appear to be 

 entirely destitute of an investing membrane; their nearly 

 elliptical nucleus is transparent and colourless, and is situated 

 nearly in the middle of the cell. The protoplasm, from its 

 behaviour when lightly pressed, must possess great tenacity 

 and extensibility, as it can be drawn out into long threads, by 

 means of which the several cells adhere to one another. Many 

 of the epithelial cells contain fat cells, whilst others exhibit 

 clear bright drops resembling vacuolse ; others, again, present 

 an irregular shrivelled form, and these may often readily be 

 completely flattened out under a covering glass, or break 

 up into a finely granular mass, if a moderately strong cur- 

 rent be established under the glass. I am inclined from all 

 this to draw the conclusion that the cells of the follicular 

 epithelium gradually break down in the liquor folliculi, and 

 that the products of their disintegration in great part form that 

 fluid, which must consequently be regarded as a transudate 

 from the blood, with epithelial cell substance in solution. 

 Upon this point the reader is referred to the statements of 

 Luschka (71). 



The liquor folliculi, when fresh, is a transparent, feebly alkaline, 

 perfectly neutral fluid, or at least becomes perfectly transparent if it 



