THE ERGASTOPLASM IN THE MAMMARY GLAND AND ITS TUMOURS 1 77 



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¥iG. 6. Typical aspect of virgin gland cells in the mouse to show the absence 

 of "organized" ergastoplasm and even the rarity of RNP-granules. In the upper 

 part of the picture is the lumen whilst at the base of the glandular cells is a myo- 

 epithelial cell. X 10 100. 



