Immunoelectron microscope demonstration of the basement membrane components laminin and type IV collagen in the dermal cylindroma.

Specific antisera to the human laminin P1 fragment and the 7S domain of type IV collagen were used to investigate the ultrastructural location of these main basement membrane (BM) components in a dermal cylindroma. Thick frozen sections were treated by the immunoperoxidase method, postfixed, embedded in epon and then sectioned for electron microscopic examination. Laminin and type IV collagen were detected in all layers of the cylindroma BM, together with non-specifically stained, diffusely distributed fibrillar structures, possible microfibrils and anchoring fibrils or residual stromal collagen fibres. The mixed presence of the BM components indicates that these substances codistribute rather than occurring as separate layers even when forming neoplastic basement membranes.