PLATE 5 



EXPLANATION OF FIGURES 



44 Stage 'c'. Nucleus of oocyte in follicle of 2 to 3 layers of cuboidal cells. 

 Mouse sexually mature (sixty-seven days p.p.). Fl., I.H. (Same ovary as 

 figure 42) 



45 Stage 'c'. Nucleus of definitive oocyte in follicle of 3 to 5 layers of cells. 

 A slight vacuolation in the follicle indicates the beginning of the formation of a 

 cavity (antrum folliculi). Adult mouse, pregnant. P.A.F., I.H. 



46 Stage 'c'. Nucleus of definitive oocyte in mature Graafian follicle (this 

 follicle is shown in text figure 7) . Adult mouse, Herm., I.H. 



47 Two cells from the germinal epithelium of an ovary twenty-eight days 

 p.p. The upper cell is an indifferent epithelial cell and the lower is a definitive 

 oocyte in stage 'a'. A mitochondrial technique was used (Benda's fluid, Cu H). 



48 Definitive oocyte in germinal epitheliimi, stage 'b'. To show mitochon- 

 dria. Zenker's + 2 drops of acetic acid; potassium dichromate, fourteen days; 

 Cu H. Mouse seventeen days p.p. 



49 Oocyte in the germinal epithelium, with cells flattened around each end 

 (figs. 28, 29). Mitochondria and idiosome shown. Same ovary as figure 48. 



50 Oocyte in the germinal epitheliiun, about the same stage as figure 28 or 29. 

 Mitochondria and idiosome are shown. The fonner are mostly granules, but 

 there is an indication of the formation of granular threads. Mouse eleven days 

 p.p. Same technique as ovary shown in figure 48. 



51 Oocyte in follicle of 3 to 4 layers of cells, showing the uniform distribution 

 of the mitochondria. The idiosome is also shown. Mouse twenty-six days old. 

 Zenker's + 2 drops of acetic acid; potassium dichromate, three weeks; Cu H. 

 X 1000. 



52 Part of an oocyte and adjacent follicle cells. Note that the mitochondria 

 in the egg-cell are all granular, while both granules and threads appear in the 

 follicle cells. Same ovary as figure 47. 



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