SUMMARYWhen rat trigeminal ganglia were osmicated for 45 h at 40°C in a 1% unbuffered aqueous solution of osmium tetroxide, only the one saccule located on the forming face of the Golgi stacks was impregnated with osmium. This staining property was therefore utilized to examine with the high voltage electron microscope the tri‐dimensional structure of the forming face of the Golgi apparatus of the small nerve cells using sections whose thickness ranged from 1 to 7 μm.In 1 μm thick sections, the osmicated ‘saccules’ actually consist of tubular polygonal networks scattered throughout the pericaryon. As the thickness of sections is progressively increased, these networks are seen to interconnect and form the so‐called ‘appareil réticulaire interne’ initially described by Golgi (1898a) in the light microscope. Stereoscopic analysis of 5–7 μm thick sections clearly demonstrates that the saccules located on the forming face of the Golgi stacks are in fact a continuous convoluted structure made up of a tubular