Contrast Staining with Reduced Osmium Complexes

Contrast Staining with Reduced Osmium Complexes -...

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0022-1554/951$3.30 The Journal of Histochemistry and Cytochemistry Copyright 0 1995 by The Histochemical Society, Inc. Letter to the Editor I Vol. 43. NO. 9, pp. 965-966. 1995 Printed in U.S.A. I Contrast Staining with Reduced Osmium Complexes Recently I read a Technical Note in the Journal of Histocbemistv and Cytocbemz’try (1) entitled: “Improved method for post-embedding cyto- chemistry using reduced osmium and LR White Resin,” by Hideaki Tamaki and Shohei Yamashina. On the one hand, I was glad to see the revival of the use of ferrocyanide as an additive to Os04 post-fixation in LR White resin procedures. On the other hand, I was disappointed when I noticed that (in a historical sense) the authors were referring to Karnovsky’s short 1971 abstract (2) and not to my more informative 1968 abstract (3), in which the use of reduced os- mium was introduced, or to later works by White et al. (4) or Hayat (5). This aspect alone would not justdy a letter to the editor. However, in the Discussion (1) (p. 1292, line 18 from the bottom) incorrect statements are present that might have escaped the referee’s attention: “The mechanism of fixation by Os04 is not fully understood. Its powerful oxidizing effect may be responsible for the fixation of macromolecules (reference to Pearse). We speculate that the effects of osmic acid [sic!] on decreasing cytochemi- cal reactivity are minimized by reduction with potassium ferrocyanide. There- fore, reactivity with moderately adequate fine structure is retained.” This is followed by two references (1984 and 1993) about the use of reduced os- mium for improving membrane contrast. I will not exclude the possibility that the first line of the quotation may have been truncated in the process of typing and printing, and that it orig- inally might have read, “is not fully understood by us,” or, “and is not available to us,” because original papers of early dates are parked along the electronic highway in library search systems, as, for example, in our library system, in which papers dated earlier than 1984 are no longer accessible electroni- cally and papers one decade before that point require special hand aching. To counteract the impact of this discussion and to contribute some in- formation in a positive way, I give below a short summary of “stale” infor- mation about this aspect of reduced osmium tetroxide in papers from our laboratory between 1968 and 1984 excluding, in an unfriendly way, those from other authors active in that period: 1. After the initial introduction in 1968, the selectivity of o~(v1II)o~ plus complex cyanides such as K$e(III)(CN)6 or QFe(II)(CN)6 for glycogen and membranes was given and illustrated in 1973 (6). 2.
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Contrast Staining with Reduced Osmium Complexes -...

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