Light and electron microscopic immunohistochemical detection of bromodeoxyuridine-labeled cells in the brain: different fixation and processing protocols.
The aim of this study was to compare two immunohistochemical methods, avidin-biotin peroxidase and immunogold silver staining (IGSS), in the detection of 5-bromodeoxyuridine incorporation in mouse embryo tissues. In addition, two fixation schedules, formal-saline and a mixture of formaldehyde and glutaraldehyde (4FIG), and two embedding procedures, paraffin wax and the acrylic resin L.R. White, were also compared. Pregnant mice were injected with 600 mg per kilogram body weight on days 10 or 15 (plug day = day 1) of gestation and the embryos recovered 2 h after treatment and fixed in formal-saline or 4FIG. Fixed material was then processed into wax blocks or L. R. White resin. After sectioning, the antigen-antibody reaction was visualized using either the avidin-biotin peroxidase or IGSS methods. All methods tested gave a well-contrasted, highly specific reaction, but IGSS in combination with 4FIG and L. R. White gave a clearer and more sensitive signal than other combinations.