New aspects on the 'rodlet cell' in teleosts.
The enigmatic rodlet cells, hitherto interpreted mainly as unidentified parasitic stages ('Rhabdospora thélohani') or as a sort of secretory cell, have been studied with electron microscopical and histochemical methods in three teleost species (Cyprinus carpio L., Tinca tinca L., Salmo gairdneri Rich.). The typical inclusions, the rodlets, consist of a dense core and a less dense cortex, with a coarse flocculent outer zone. The latter shows a positive reaction for neutral polysaccharides respectively glycoproteins (with the silver proteinate method and the equivalent silver methenamine-staining), concurring with some of the light microscopic data. While this suggests the secretion of this material by the Golgi apparatus, the core gives contradictory results, pointing to genetic material instead of a secretory product. Although the Feulgen method (as standard test for DNA with only a few exceptions known) is negative, DNA is indicated by several other methods (light microscopical fluorescence staining with HOECHST 33258, EDTA-method after Bernhard (1969), enzyme digestions positive with DNAse and negative with RNAse). Taken together with some observations on the tissue reaction (phagocytosis of the often discharged rodlets by macrophages and also the more specifically acting heterophilic granulocytes; isolation of the rodlet cells from the adjoining tissue as seen e.g. with the ruthenium red method), an exogenous parasitic nature of these cells seems more plausible, even if the evidence is not sufficient for an exact classification of either the cell or its characteristical inclusions.
D000818:Animals; D004247:DNA / Q000032:analysis; D005399:Fishes / Q000033:anatomy & histology* / Q000469:parasitology; D006003:Glycogen / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis; D007668:Kidney / Q000166:cytology; D011134:Polysaccharides / Q000032:analysis; D014018:Tissue Distribution
D006023:Glycoproteins; D011134:Polysaccharides; D006003:Glycogen; D004247:DNA