Golgi-Colonnier method: correlation of the degree of chromium reduction and pH change with quality of staining.

Abstract

We examined the role of chromium reduction in the Golgi-Colonnier method, correlating the quality of neuronal impregnation with the levels of hexavalent (CrVI) and trivalent (CrIII) chromium in the tissue and in the chromation fluid (CF). The concentrations of both chromium species were assessed by measuring spectrophotometrically the CrVI before and after oxidizing the sample and by calculating the ratio of CrVI to total chromium (chromium ratio, CrR). The CrR was almost identical in the tissue and the CF, decreasing exponentially during chromation due to a progressive consumption of CrVI to form CrIII. Satisfactory cell impregnation was obtained only when the CrR was 0.45-0.7, regardless of other factors. The CrR values could be accurately predicted by the pH increase of the CF; this increase has proven to be a most reliable criterion to decide the endpoint of the chromation process. The dependence of cell staining on the [CrIII], together with the well-known ability of this species to bridge proteins, suggests that the key event for cell impregnation is the cross-linking of neuronal proteins by CrIII polymers.

Alteraciones de la morfología dendrítica neuronal en la corteza cerebral de ratones infectados con rabia: un estudio con la técnica de Golgi

“…Los aldehídos reducen el Cr VI a Cr III , un proceso que depende del pH de la solución. El Cr III establece puentes de unión con las proteínas, un hecho que los autores consideran determinante en el proceso de impregnación (29). Quizá la infección con el virus de la rabia desencadena cambios bioquímicos en el tejido nervioso que podrían interferir con este mecanismo de impregnación.…”

A Modified Method for Consistent and Reliable Golgi–Cox Staining in Significantly Reduced Time

“…However, the main drawback of the method is inconsistency of impregnation of the stain into the neurons resulting in reduced specificity, reproducibility, and success rate (Globus and Scheibel, 1966; Pasternak and Woolsey, 1975; Zhang et al, 2003). Several modifications of the method have been tried which include variations in pH (Bertram and Ihrig, 1957; Gonzalez-Burgos et al, 1992; Angulo et al, 1994), application of vacuum (Friedland et al, 2006), coating of brain blocks with egg yolk (Zhang et al, 2003), use of microwaves (Armstrong and Parker, 1986; Marani et al, 1987; Zhang et al, 2003) and variations in temperature of the tissue incubating medium (Armstrong and Parker, 1986; Berbel, 1986; Marani et al, 1987; Angulo et al, 1994). These modifications were aimed at faster staining process by decreasing the time for staining, reducing precipitation, promoting uniform crystallization, increasing reliability, and reproducibility of staining neurons by the Golgi method.…”

Differential staining of glia and neurons by modified Golgi-Cox method

“…It was postulated that changes in intracellular concentrations of Na + , K + , Cl − may affect the impregnation and color (Kuner and Augustine, 2000;Silver et al, 1997;Smith et al, 1981). Similarly, other studies have indicated that membrane resting potential (Silver et al, 1997), which may influence the electrical charges on proteins of neurons and glia after fixation by affecting the formation of positively charged Cr III -protein complexes, may also be responsible for impregnations and staining (Angulo et al, 1994). As the fixatives are known to cross-link between proteins in tissue by creating covalent chemical bonds and denature them (Fox et al, 1985), it is possible that the fixatives cross-link some glia-specific protein in a particular manner to be better stained by Golgi-Cox stain.…”

“…Additionally, several workers tried modifying other conditions viz. used vacuum (Friedland et al, 2006), changed temperatures (Angulo et al, 1994;Berbel, 1986), used microwave energy (Armstrong and Parker, 1986;Marani et al, 1987;Zhang et al, 2003) to improve staining by Golgi and its variants described above. Although some of these modifications somewhat improved the quality of staining and others reduced time taken for staining, consistency and reproducibility of results were still unsatisfactory.…”