The network of interconnected tubular and cisternal structures located within the Golgi apparatus on the side distal to the endoplasmic reticulum, from which secretory vesicles emerge. The trans-Golgi network is important in the later stages of protein secretion where it is thought to play a key role in the sorting and targeting of secreted proteins to the correct destination.
Related synonym
Golgi trans face, Golgi trans-face, late Golgi, maturing face
Comment
There are different opinions about whether the TGN should be considered part of the Golgi apparatus or not. We follow Alberts et al, 1994 (ISBN:0815316194), who consider it to be a part.