384 THE CORPUS LUTEUM OF DASVmrS, 



follicles. These are leucocytes, with the function of removing 

 the granular debris; and there does not, in iJ)asyurus, appear to 

 be any reason for thinking that these are membrana granulosa 

 cells with a phagoc3'tic action, such as has been attributed 

 to them b}'' some authors, e.//., Schulin, Janosik, and Pfliiger. 

 AVhilst the ovum is degenerating similar cells are sometimes found 

 attacking it, but nowhere is there seen any sign of the trans- 

 formation of membrana granulosa cells into a plasmodium, with 

 the phagoc3^tic action, as described by Match insky, though in 

 small atrophic follicles there are sometimes found appearances 

 similar to those figured by Matchinsk}', which are but remnants 

 of degenerated ova containing nucleated leucocytes (fig. 21). 



The basal membrane is early affected. It disappears whilst 

 the above described changes are going on. It is generally an 

 earl}' event, but may be late. The time of its disappearance 

 varies, but whilst it is present there is no tendenc}' for the inner- 

 most layer of the theca foUiculi to encroach on the membrana 

 granulosa (see figs. 19 and 20). 



When the basal membrane disappears, the rudimentary theca 

 interna folliculi encroaches on the membrana granulosa. It 

 becomes thickened, its cells increase in size and project into the 

 membrana granulosa, and even into the cavity of the follicle. 

 With the atroph}' of the remaining membrana granulosa cells, 

 there is also multiplication of the cells of the theca interna, so 

 that concentric la3^ers of connective tissue cells are formed, 

 tending to diminish the size of the follicular cavity. This process 

 is aided by the ingrowth of connective tissue cells into the cavity, 

 causing its ultimate obliteration. 



In the second variety of these atrojjhic follicles, where there 

 remains but one layer of cells of the membrana granulosa lining 

 the ca^'ity, the ordinary separation of the rudimentar}- theca 

 interna from the membrana granulosa by the basal membrane, 

 though present, is obscured, and there is no attempt at encroach- 

 ment on the membrana granulosa by the theca folliculi, so that 

 the atrophied follicle presents the appearance of a cyst, lined by 

 a definite layer of more or less cubical epithelium, towards which 



