Golgi complex--endoplasmic reticulum transition region has rings of beads

The smooth surface of the rough endoplasmic reticulum that makes the forming face of the Golgi complex has beadlike structures arranged in rings at the base of transition vesicles. The beads can only be seen easily after staining in bismuth salts. They are 10 to 12 nanometers in diameter and occur in a variety of cell types and organisms.