title: Histochemical observations on Pneumocystis carinii: selective demonstration of honeycomb forms.
abstract: Histochemical investigations of pulmonary lesions indicated selective coloration of membranes of honeycomb stages of Pneumocystis carinii by the periodic acid--sodium bisulfite--resorcin-fuchsin reaction for basement membranes; mucus, fibrin and other deposits in respiratory pathways did not react. These membranes were colored selectively also by the picro-Sirius Red F3BA method for collagens; fungi in tissues from patients with candidiasis remained unstained. For simultaneous demonstration of honeycomb and cyst forms of Pneumocystis carinii, sections were prestained with Grocott's modification of Gomori's methenamine-silver nitrate technic and then treated with the periodic acid-Schiff (PAS) or picro-Sirius Red F3BA reaction. In contrast to other Gram-positive microorganisms, cysts of Pneumocystis carinii were immediately decolorized by acetone-ether mixtures; this indicates differences in the mode of dye binding. Frequently, only one stage of Pneumocystis carinii was found in a given area. Hence a combination of reactions showing different stages is recommended for studies of small tissue samples.
mesh_terms: D001485:Basement Membrane / Q000166:cytology; D006652:Histological Techniques; D006801:Humans; D008168:Lung / Q000473:pathology*; D011010:Pneumocystis / Q000166:cytology*; D011020:Pneumonia, Pneumocystis / Q000473:pathology*; D013194:Staining and Labeling / Q000379:methods