4/16/2023 0 Comments Stain precipitate![]() ![]() The use of sodium thiosulfate, or “hypo”, helps to remove any unbound silver remaining from the toning reaction. Toning of the sections in gold chloride is a chemical reaction whereby the metallic silver is replaced by metallic gold, which is very stable and maintains the black color product. ![]() This allows the structures in question to be visualized in dark black staining. The reduction step in the reaction involves providing electrons, in the form of substances such as hydroquinone and formaldehyde, to chemically make the silver ions precipitate out into visible metallic silver. The idea is to have the silver carrying solution composed such that the silver ions will move from the solution, bind to the tissue section and then precipitate out in metallic form. Silver impregnation solution contains metallic silver in a solution. However, Margeson and Chapman pioneered the substitution of zinc formalin for the original radioactive uranyl nitrate solution, which is also a strong oxidizer. The original sensitizer for Wilder’s silver technique and the Steiner and Steiner stain is 1% uranyl nitrate. Sensitization usually employs a metal salt to help bind silver from the silver solution. Oxidizers include phosphomolybdic acid, potassium permanganate and periodic acid. Oxidation enhances subsequent staining by the silver solution. However, the following stain procedure outline explains the steps used. The specific procedures for these stains are outside of the scope of this blog. The goal of all silver stains is the same: to get metallic silver to precipitate out at the staining site, and then replace it with gold to provide the final, stabilized, black reaction product. Silver stains can be categorized into (a) stains to visualize substances, such as calcium, melanin and reticulin and (b) stains for microorganisms, such as fungi and spirochetes. All other special stains, with few exceptions, are relatively easy and straightforward to perform not so with silver stains. In the histology world, the mere mention of a “silver stain” may be the cause of panic and uncertainty with regard to the performance of the stain, and the quality of the final resulting microscope slide. Berlin-Heidelberg-New York: Springer 1967.Twitter Facebook LinkedIn Messenger Print SMS Email WhatsApp 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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