554 THE STRUCTURE AND DEVELOPMENT 



The ova have grown very greatly, and it appears to me to be 

 mainly owing to their growth that the greater thickness of the 

 epithelium is due, as well as the irregularity of its inner surface 

 (vide fig. 9). 



The general relation of the epithelium to the surrounding 

 parts is much the same as in the earlier stage, but two new 

 features have appeared (i) The outermost cells of the ovarian 

 region have more or less clearly arranged themselves as a 

 kind of epithelial covering for the organ ; and (2) the stroma 

 ingrowths of the previous stage have become definitely vascular, 

 and have penetrated through all parts of the epithelium. 



The external layer of epithelium is by no means a very 

 marked structure, the character of its cells varies greatly in 

 different regions, and it is very imperfectly separated from the 

 subjacent layer. I shall speak of it for convenience as psendo- 

 epithclimn. 



The greater part of the germinal epithelium forms anasto- 

 mosing columns, separated by very thin tracts of stroma. The 

 columns are, in the majority of instances, continuous with the 

 pseudo-epithelium at the surface, and contain ova in all stages 

 of development. Many of the cells composing them naturally 

 form the follicular epithelium for the separate ova; but the 

 majority have no such relation. They have in many instances 

 assumed an appearance somewhat different from that which 

 they presented in the last stage, mainly owing to the individual 

 nuclei being more widely separated. A careful examination 

 with a high power shews that this is owing to an increase in the 

 amount of protoplasm of the individual cells, and it may be 

 noted that a similar increase in the size of the bodies of the cells 

 has taken place in the pseudo-epithelium and in the follicular 

 epithelium of the individual ova. 



The stroma ingrowths form the most important feature of 

 the stage. In most instances they are very thin and delicate, 

 and might easily be overlooked, especially as many of the cells 

 in them are hardly to be distinguished, taken separately, from 

 those of the germinal epithelium. These features render the 

 investigation of the exact relation of the stroma and epithelium 

 a matter of some difficulty. I have, however, been greatly 

 assisted by the investigation of the ovary of a young example 



