Some variations even wash the silver oxide with distilled water before adding ammonium hydroxide to redissolve it, claiming that this gives a cleaner background. There are many variations for producing these solutions, differing by the volume and concentration of silver nitrate used and the chemical used to produce the initial precipitate of silver oxide, whether this be ammonium hydroxide, sodium hydroxide or sodium carbonate. Do not return it to the stock ammonium hydroxide bottle. Discard any ammonium hydroxide that is unused. The solution in the beaker may then be used to make the ammoniacal silver solution. It is advisable to open a stock bottle of ammonium hydroxide only long enough to pour some into a beaker, then to recap it securely. The resulting ammoniacal silver solutions may not work properly and the impregnations may fail. Such depleted solutions should not be used to make ammoniacal silver solutions. Ammonium hydroxide solutions give off ammonia when exposed to air and old solutions may have lost a distinct amount of their ammonium hydroxide content as a consequence. The ammonium hydroxide must be saturated and should have a specific gravity of 0.88. with a doubled "m", but they all refer to the same thing. The "diamin-" in the names may be spelled as "diammin-", i.e. It is variously known as silver diaminohydroxide, silver diamine (with or without the word " hydroxide" added), diamine silver, Tollen's reagent or, most commonly in histology, ammoniacal silver solution, and contains compounds based on the following structure - OH. On the addition of more ammonium hydroxide, the precipitate redissolves by forming a complex with the ammonia. Their preparation is based on the fact that ammonium hydroxide, when added to a simple aqueous silver solution, causes a precipitate of silver oxide to form. These are made by adding strong ammonium hydroxide (concentrated ammonia, specific gravity 0.88) to an aqueous silver nitrate solution. Berlin-Heidelberg-New York: Springer 1967.Many silver impregnations employ ammoniacal silver solutions, sometimes referred to as silver diaminohydroxide solutions. Reimer, L.: Elektronenmikroskopische Untersuchungs- und Präparationsmethoden, 2. Berlin-Heidelberg-New York: Springer 1970. In: Contemporary research methods in neuroanatomy (W. Ramón-Moliner, E.: A tungstate modification of the Golgi-Cox method. Mayer, P.: Über die sogenannten Sublimatkristalle in mikroskopischen Präparaten. In: Enzyklopädie der mikroskopischen Technik (R. : Sur l'anatomie microscopique des organes centraux du système nerveux. Golgi, C.: Di una nuova reazione apparentemente nera delle cellule nervose cerebrali ottenuta col bicloruro di mercurio. J.: Golgi potassium-dichromate silver-nitrate impregnation: Nature of the precipitate studied by X-ray powder diffraction methods. 80, 91–92 (1950).Ĭox, W.: Imprägnation des centralen Nervensystems mit Quecksilbersalzen. C.: A standard substance for precise electron diffraction measurements. K.: Staining formalin-fixed nerve tissue with mercuric nitrate. Oxford: Blackwell Scientific Publications 1965.īertram, E. In: Techniques for electron microscopy (D. It appears reasonable to assume that, when no crystalline compounds can be detected, metallic liquid mercury is formed.Īlderson, R. The mercurous chloride is topographically associated exclusively with the presence of stained structures and cannot be detected in the non-stained background.įollowing the alkalinizing process necessary for the final darkening of the stained structures, the X-ray diffraction pattern of mercurous chloride usually was no longer detectable. There appears to be no formation, at any time, of mercurous or mercuric chromate. The approach was a twofold one: the study of the patterns of X-ray diffraction of successfully impregnated tissue and the analysis of electron diffraction patterns of selected areas of tissue where impregnated structures were observed.Įvidence has been obtained that the precipitate, prior to the final alkalinization process, is mercurous chloride (calomel, Hg 2Cl 2). An investigation was carried out to determine the nature of the precipitate in a technique which was originally proposed by Golgi and, later, modified by Cox, to stain nerve cells by the treatment of tissue with potassium dichromate and mercuric chloride.
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