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Figure 1. Field emission in-lens scanning electron micrographs (FEISEM) of sclerotic dentin after double-immunolabeling with monoclonal antibodies for type I collagen and proteoglycans. The images were obtained by a combination of secondary electron and back-scattered electron signals. (A) Low-magnification view of the surface of sclerotic dentin reveals partially patent tubular orifices surrounded by thick collars of peritubular fibrillar structures. Intertubular dentin is highly porous and is heterogeneously covered with the large (30 nm) gold particles used for labeling of antigenically intact collagen fibrils. Gold nanoparticles (15 nm) for labeling chondroitin sulfate cannot be discerned at this magnification. (B) A higher-magnification view of the sclerotic intertubular dentin, showing the labeling patterns for type I collagen (arrows) and chondroitin sulfate (open arrows). Only a few nanoparticles specific for chondroitin sulfate can be visualized at this level of magnification.
