Ultrastructure shown here of more unusual protein structures within the RER of type II alveolar cells, these are really not at all like what I have been thinking are SP-A, but are more like fuzzy balls.  The dimensions of the rounded electron dense  accumulations within the cisternae of RER within this type II cell are about the dimension of 100+ nm.  The comparison in size between three ribosomes from this same image (see the inset in lower right at actual size) and three of the fuzzy balls? perhaps, in the same inset at actual size, and then see the two types of structures, i.e. the ribosomes and the fuzzy balls enlarged to the same degree and pseudocolored in the inset to compare their relative sizes.  The ribosomes are supposed to be something around 20-25-30 nm in that range, and if these are fuzzy balls (that would be multimers of surfactant protein D) then the fuzzy balls should be about three diameters compared to the ribosomes.  Doesn’t quite work out, so the identification of these electron dense objects within the cisternae of RER in this electron micrograph is up for grabs.  Nucleus is pseudocolored blue, nuclear pore, green, RER profiles with the odd protein, orange, actual size ribosomes and fuzzy balls grey, in inset, and enlarged in relative size, ribosomes, blue, fuzzy balls red.