Type III: small, banded; reticular CT (CT of organs), smooth muscle, endoneurium, blood vessels, lung, lymphoid tissues, bone marrow, and fetal skin. Can only be viewed with special staining (heavy metals).
Reticular CT is a type of collagen. It appears different because of the Type III collagen, which is a very thin fibril that forms a loose mesh of support, especially prevalent in lymphoid organs and bone marrow. Reticular fibers are so fine that normal H&E staining does not allow viewing with the light microscope, a heavy metal stain (silver) is usually needed.