This electron micrograph just made me chuckle because for whatever reason the fixation of this particular profile of RER just had four cute little ribosomes lined up and stringing out from them into the lumen of this profile of RER were four strands of protein, even to the point of having a little kind of fat area at the leading end….

Here is a contrast enhanced (I did use the burn tool in photoshop on the ribosomes and the protein) portion of that ferret type II alveolar cell, and below that is the area from which I cropped the profile of RER.  Magnification and enlargement can be approximated from the ribosomes… which are @ 25 nm in diameter.  Below that is the original micrograph, not retouched.