Golgi EM

Electron micrographs reveal Golgi as a series of flattened, membrane-bound cisterna. Each cisterna contains a unique set of enzymes that modify the sugar side chains on proteins. Vesicles from the endoplasmic reticulum fuse with the cisternae on the cis side. Proteins are shuttled between cisterna by vesicles. Proteins leave the Golgi on the trans side and are delivered to the plasma membrane, endosomes/lysosomes, or stored in secretory vesicles.