A combination of intravascular resin injection and formic acid incubation was utilized to study the three-dimensional arrangement of the elastic fibers in the loose connective tisue (superficial fascia) of the rat limb by scanning electron microscopy (SEM). The cast of the microvasculature served as a scaffolding for the otherwise collapsible connective tissue.
SEM study demonstrated that the elastic fibers did not form an anastomosing network but were arranged in multiple layers. The fibers in each layer lay parallel to each other but were oriented differently from the fibers in the layers on either side, thereby producing a meshwork. Each individual fiber was composed of a small bundle of discrete fibrils. Some of these component fibrils separated from the parent fiber and united with other fibers, thus producing branching. The elastic fiber either decreased or grew in size by the respective sharing or joining of these component fibrils with neighboring fibers in their respective layers. Interconnections between elastic fibers of different layers were rare.
These findings may provide a morphological explanation for the characteristic function of the superficial fascia, which allows the skin and underlying muscles to have a rapid and extensive alteration in their relative positions.