Osmium tetroxide/p-phenylenediamine staining of nucleoli and balbiani rings in Chironomus salivary glands

Summary This paper deals with the application of the osmium tetroxide fixation followed by p-phenylenediamine treatment to salivary gland cells from Chironomus larvae. After this procedure, cytoplasm, nucleoli and Balbiani rings show a high degree of staining both in light and electron microscopy, while chromatin remains unstained. Ethanol fixation followed by osmium tetroxide/p-phenylenediamine does not modify the above mentioned staining pattern. Under these conditions, extractive procedures for lipids do not affect the osmiophilia of nucleoli and Balbiani rings, while RNase or trichloroacetic acid treatment decreaes the staining degree of these structures. In osmium tetroxide/p-phenylenediamine treated salivary glands, the highest contrast within nuclei is seen to occur in the pars granulosa from normal or segregated nucleoli, as well as in Balbiani ring granules, which appear either as hollow granules or with a bipartite or horseshoe-like structure.