Golgi membranes. Transmission electron micrograph (TEM) of a section through a cell, showing the membranes (dark lines) of the Golgi apparatus. The multiple, stacked membranes of the Golgi apparatus are the site of protein synthesis within a cell. They are often clustered in specific areas of the cytoplasm and feature prominently in any cell actively engaged in synthesis of products destined for secretion, such as enzymes. The Golgi packages and transports its macromolecule products in vesicles (dark circles) assembled by the Golgi membrane stacks. Magnification: x42,000, when printed 10 centimetres wide.