Direct observation of immunoreactive sites and antibody molecules by ultrahigh-resolution scanning electron microscope.

Using an ultrahigh-resolution scanning electron microscope (SEM), an attempt was made to directly visualize antibody molecules at antigenic sites in rat pancreas or on silicone plates. Although individual antibody molecules could not be discerned, a fluffy meshwork, probably indicating several molecules, was seen. With further improvements in specimen preparation, the high-resolution SEM promises to be an important tool in examining individual antibody-antigen sites without the need of an electron-dense label such as colloidal gold.