Ultrastructural distinction between reticular and collagenous fibers with an ammoniacal silver stain

摘要

AbstractReticular and collagenous fibers stain differently when subjected to ammoniacal silver reduction. A variety of tissues were subjected to such a “reticulin” technique and the association of reaction product with intercellular connective tissue elements was studied with the electron microscope. The reaction with reticular fibers was primarily associated with the interfibrillar matrix, and was globular in form having a wide variety of particle sizes. Conversely, in dermal collagen the unit fibrils were stained rather than the interfibrillar matrix. The precipitate was punctate in form and was associated with the cross striations of unit collagen fibrils. Large microfibrils also reacted positively with the stain, imparting a faint periodicity. Basement membranes were stained uniquely. The underlying plasmalemma and the lamina densa were heavily stained with silver while the lamina lucida was relatively unstained. The unit fibrils of the lamina reticularis stained in the same manner as dermal unit collagen while the ground substance remained unstained. This represents a clear distinction between the argentophilic characteristics of collagenous fibers, reticular fibers, and basement membra