A 3-D model of the three trans-Golgi cisternae and associating ER in a portion of the Golgi stack. The modeled cisternae (in cis-to-trans order) are colored rose (C5), gold (C6) and red (C7). The associating trans-ER is blue-gray. Clathrin-coated budding profiles are indicated by yellow stippling, which are present only on the red C7 cisterna. C7 produces only clathrin buds and does not produce uncoated or non-clathrin-coated buds. The model also shows that trans-ER associates, to varying degrees, with all three of the modeled cisternae. This specialized form of ER was originally termed the GERL by Alex Novikoff in 1964. The penultimate trans-cisterna is extremely reticular and a tubule extends from C6 trans- of the trans-most cisternae C7, but is not fused with the trans-most cisterna.