Immunostained tissue sections are observed in the light microscope with typical Köhler’s bright field illumination.
Apart from contrast enhancement by postfixation with OsO4, peroxidase stained slides might be also counterstained with hematoxylin or with methyl green. Photographs were taken with an automatic microscope camera equipped with an electronic switch unit. Photos are usually recorded on 35 mm black and white negative film (e.g. 18 DIN/50 ASA), on 35 mm tungsten color reversal film (e.g. 18 DIN/50 ASA; 3200ºK) or on daylight color reversal film (e.g. 18 DIN/50 ASA; 5500ºK). In the latter case, the lamp temperature is corrected from 3100ºK to 5500ºK by a conversion filter. The exposure time is modulated by gray filter.
Ultrastructural studies of tissues are performed with ultrathin sections (<0.1 µm thick) by use of conventional transmission electron microscopes operating at 80 kV with bright field illumination. Sections are photographed with commercial film material (6.5 x 9 cm). Sections from immunoperoxidase reacted tissues can be counterstained with lead citrate for 30 sec which anhances the contrast of cells and the cytochemical reactions.