76 



SUBCELLULAR PARTICLES 



Fig. 6. Guinea pig fed after a fast of 4M hours. Limited field at the periphery of the centro- 

 sphere region of an exocrine cell. Profiles of rough -surfaced {rs) elements of the endoplasmic 

 reticulum can be seen along the left margin of the figure. St>me of them contain intracisternal 

 granules {short arrows). The smooth-surfaced elements of the centrosphere region occupy the 

 rest of the field and appear either as arrays of elongateil profiles {ss\) or as scattered circular 

 profiles {SS2) of variou.s dimensions. An element of intermediate appearance (part rough and 

 part smooth) is marked by a long arrow. The large vesicles with a dense, homogeneous content 

 (01, 2:2, ^3) represent zymogen granules in formation. Almost mature zymogen granules can be 

 seen at s* and z^'. X 32,000. 



