1905.] the Interstitial Cells of the Ovary in the Rabbit. 35 



mixture of sublimate (saturated) 4 pints, formol 1 pint, and 1 per cent, glacial 

 acetic for other purposes. 



The sections fixed in Gilson's fluid were stained with iron hsematoxylin, or 

 hsemalurn ; those fixed in the other solution stain well either with iron heema- 

 toxylin, haemal um and eosin, or toluidine blue and eosin. 



Changes in the Cells of the Germinal Epithelium in the Immature Rabbit. 



The origin of the germinal epithelium from the peritoneum by a process of 

 differentiation has been so fully shown by several observers, that it will not 

 be necessary to deal any further with the origin of the germinal cells. Also 

 it has been shown that these cells become embedded in the underlying 

 mesoblast ; this state of affairs is seen in an embryo of the twentieth day. 



The ovary is by this time a definite organ ; it is intensely vascular, showing 

 large blood spaces, especially in the parts lying immediately round the 

 mesoblastic core. At this period the main mass of the germinal cells is 

 situated peripherally, only a few isolated ones having penetrated into the 

 core, which last is sending processes of connective tissue in between groups of 

 germinal cells. Of these there are present a large number of protobroque and 

 a few deutobroque ; also a certain number of mitotic figures, but these are not 

 numerous. (See Plate 1, fig. 1.) 



From this time onward until after birth the changes in the ovary, as seen 

 under the low power of the microscope, are not striking ; there are more 

 deutobroque cells, characterised by their transparent appearance, and there is 

 an increase in the number of mitotic figures. 



Studied under the high power of the microscope some of the deutobroque 

 cells are seen to have entered upon the early stages of ovogenesis, and to have 

 reached the leptotenic stage. There are large numbers of round cells showing 

 a nuclear structure differing from either the protobroque or the deutobroque 

 cells. The mitoses are chiefly found near the periphery, and the greater 

 number of them seem to be taking place in the large cells. I do not 

 altogether agree with v. Winiwarter on the question of mitosis in these cells. 

 In the first place tbere appears to be very little distinction between the 

 varieties of protobroque cell, a and b, and I shall not dwell upon it. The 

 mitosis in the protobroque cells does not appear to be sufficient to account for 

 the large number of deutobroque cells which are formed, and my observations 

 are to the effect that by far the greater number of mitoses are taking place in 

 the deutobroque cells themselves. Each class of cell divides, the protobroque 

 less copiously than the deutobroque, giving rise to two cells of their own 

 variety. There can be no doubt that the deutobroque cells are modified 



d 2 



