rrr, 



CITji 



cm- 



B.. M 



M 



Fig. 4. Apical pole of acinar cell of guinea ])i.u pancreas, z = zymogen 



granule; zc = zymogen content which is already in lumen of pancreatic duct; 



cmi and cmg =- cell membranes of adjacent cells which are in continuity with 



membrane (zm) of zymogen granule. 



Magnification = 40,000. (Kindly loaned by G. E. Palade, unpublished.) 



