Electron microscopic localization of 1D9-immunoreactive proteins in prestained epoxy-embedded preparations of rat liver peroxisomes. Nycodenz-purified rat liver peroxisomes were processed for pre-embedding double immunoelectron microscopy (see Methods). Rabbit anti-PMP70 (α-PMP70) and mouse monoclonal 1D9 antibodies were used as primary antibodies, and 12 nm gold-conjugated anti-rabbit IgG (α-12 nm gold) and 18 nm gold-conjugated anti-mouse IgG (α-18 nm gold) as labels. The primary antibodies were omitted from samples used as negative control (left column). The images were obtained from 75 nm (upper panels) and 300 nm thick (lower panels) sections. The original magnification was 27,800-fold; the scale bar represents 500 nm.