THE ERGASTOPLASlM IN THE MAMMARY GLAND AND ITS TUMOURS 17I 



the Golgi vacuoles that these granules are found before they break out 

 into the granular lumen (see Fig. S). 



The part plaved bv the ergastoplasm in the elaboration of these protein 

 granules is not clear [^, 6]. All our present knowledge, however, indicates 

 that its role is fundamental. 



This interpretation is based on : (i) the continuity which exists between 

 ergastoplasm and Golgi apparatus, the whole membrane system of w^hich 

 constitutes the endoplasmic reticulum; (2) the enzymic studies of the 







Fig. 2(a). Lactating mammary gland. Aspect of ergastoplasm in the light 

 microscope. .After toluidine blue staining it appears as dense basophilic masses 

 ( -) X 1600. 



Rockefeller School in particular, which have shown that in the pancreas 

 the same enzymes were present in the RNP-granules and in the final 

 secretion granule [7a]. 



The first fact, the continuity of the membrane svstem is established 

 now in a suflicient number of different tvpes of mammalian cells to be 

 considered as valid for all types of cells ([i], and Porter in this symposium). 



The second fact is not yet biochemicallv demonstrated for glandular 

 organs other than pancreas but the similarity of the ultrastructural pattern 

 of all secretory cells studied up to now is strong indication that comparable 

 mechanisms are invoked in all cases. 



On morphological grounds on the other hand, evidence is not easy to 



