OOGENESIS IN THE WHITE MOUSE 275 



diplotene germ cells, and those in the following stage (dictye 

 or dictyate) are in follicles more advanced in development. 



The idiosome is clearly distinguishable for the first time in the 

 diplotene stage. A mitochondrial technique is apparently the 

 best method for bringing this out, but it is visible after Flemming's 

 or Hermann's fluids. It appears as a deeply staining body in 

 the cytoplasm, close to the nucleus. At first it is hidden in the 

 crescent-shaped mass of mitochondrial granules, but when these 

 become scattered through the cytoplasm, as happens shortly, 

 the idiosome stands out clearly. Only occasionally are centro- 

 somes seen in it. 



There is a certain overlapping of this stage and the next, the 

 'dictye' or 'dictyate.' In many cells, while some chromatin 

 threads are splitting, others begin to thin out and lose their 

 character of threads or bands. The chromatin becomes arranged 

 in irregular masses and granules at the intersections of a net- 

 work or reticulum made up, partly of chromatin and partly of 

 linin (figs. 21 to 23). One large nucleolus and two or more 

 smaller ones are usually present. The chromatin and linin are 

 frequently in close relation with the large nucleolus which stains 

 much less intensely as it enlarges. The idiosome is plainly 

 visible in the cell near the nucleus, and the mitochondria, 

 mostly granules, but with beaded rods and threads appearing 

 in increasing numbers, are evenly scattered throughout the 

 cytoplasm. 



Von Winiwarter and Sainmont ('08) consider this stage, dictye 

 described and named by the former in his work on the rabbit 

 a form of degeneration and not a normal step in development. 

 R: Van der Stricht ('11) who employs von Winiwarter's termi- 

 nology, states that this is not always a stage marking degeneration, 

 but is frequently normal, appearing in maturing Graafian follicles. 

 In the mouse, this stage bears a resemblance to the later phases 

 of the development of the definitive oocytes (figs. 44 to 46), and 

 is to be correlated with the marked growth in size of both nucleus 

 and cell. This growth, together with the fact that these cells 

 degenerate without forming ova, undoubtedly are important 

 factors in producing these nuclear changes. This degeneration 



