Here is a tangential view of the end of an intracisternal body in a type II cell of a ferret which shows, opportunely, an area of about 45 ribosomes (which would be producing the protein within the RER I am calling an intracisternal body, or a granule.  This is an educated guess, since what is behind or in front of the tangential is not really visible, but can be assumed. I am quite certain the original block for transmission electron microscopy has been cut past this field.  The grid overlay in this animation shows the spacing of about 3 ribosomes @ 100 nm.  This is not a complete match for the number of ribosomes I had counted on the growing end of an intracisternal body, which was inbetween 2 –  4, 2 for an incidentally cut period, and 4 for the most opportune.

What is amazing is the regularity of their assembly here, and their regularity in size.