[单选题]
The following electron micrograp+pz:+xvu +0j(qw *x4o6b *(z qrhorncfkt7 lxh shi0h)cszjce5 f 5 sx.:mows part of an exocrine pancreas cell. Which of the labelled structures is responsible for the production of vesicles f5s.fiz:j m 0scc )hex5or exocytosis?