Cat (feline) alveolar type II cell RER: is this a layered granule in the RER? It has only about two of the characteristics of what I think is surfactant protein in the RER which is three species makes a highly layered secretion granule which fits a little nicely with a parallel arrangement of a four stack of surfactant protein A. (that is probably not the best way to describe it, but a vertical stack of two mirrored surfactant protein A groups, stacked again and then replicated side by side many times seems to fit what is seen in some granules). Rabbit alveolar type II cells have some indication that a similar RER granule might be present, other species, not so much.  Hamster and cat come close, but do not really fit well.  BUT case in point, here is an alveolar type II cell from a cat, which shows RER profiles with one of the important criteria for being called a surfactant protein granule, and that is the loss of ribosomes on the long axis of the granule (typically parallel to the layering) and the presence of stacked ribosomes  (seemingly 4 per period (one period being two outer dense layers and one central pretty much dense layer), one ribosome on the dense bands each, and two ribosomes on either side of the central band)…. so here just on the end of this profile of RER in the cat alveolar type II cell is a stack of 4 ribosomes, and then tangential off to the right is a series of 4 ribosomes stacked as well.  Image below and inset are not enhanced or photoshopped except to increase contrast slightly. dust and scratches remain.  bar = approximately 100 nm (determined from the presumed 27 nm (give or take) mammalian ribosome size.