Abstract
A glutaraldehyde-K2Cr2O7 procedure intensified by silver staining enabled norepinephrine and epinephrine cells to be distinguished readily in paraffin sections of the adrenal glands of rats 8 days after birth. The technique involved fixation in 0.1 M cacodylate-buffered 5% glutaraldehyde (6–24 hr), treatment with 3.5% K2Cr2O7 (6–12 hr) and routine preparation of paraffin sections. The sections were deparaffinised, brought to water and immersed in Fontana's solution (24 hr), prepared by adding concentrated NH4OH drop by drop to 5% AgNO3 until the precipitate formed just redissolved; more 5% AgNO3 was then added until a permanent cloudiness just developed. After a rinse in distilled water, the sections were treated with 0.5% gold chloride (5 min) and Na2S2O3 (5 min), then mounted in Depex. This sequence resulted in an intense black cytoplasmic colouration in norpinephrine-containing cells of both the adult and 8–day-old animals whereas epinephrine-containing cells remained colourless. The glutaraldehyde-K2CrO7 procedure, without intensification, gave very clear results in the adult: a yellow cytoplasmic colour in the norepinephrine cells with epinephrine cells colourless. A glutaraldehyde-OsO4 sequence gave a less well defined separation of these cell types in the adult and failed to distinguish the cell types in the neonate.