Iron and Aluminum Lakes of Gallo Blue E As Nuclear and Metachromatic Mucin Stains

Gallo blue E, C. I. No. 51040, Mordant Violet 54, furnishes a blue black nuclear stain when applied to tissue sections in the form of its moderately stable iron lakes. This adoring combined well with such counterstains as orange G and eosin B. The Van Gieson stain tends to decolorize mucins, cartilage, and mast ells previously stained with this dye. Its aluminum lake solutions tend to gel in a few minutes to 24 hours depending on the solvent wed and the amount of Al²⁺ present. Aluminum lake solutions give a moderately good blue to dark blue nuclear stain and a brilliant purplish red to dark purple stain to a variety of epithelial and connective tissue mucins. Acid dye counterstains are poorly tolerated. With either lake, nuclear staining is abolished by deoxyribonuclease digestion or relatively short mineral acid extraction of DNA.     

Studies on Polychrome Methylene Blue III. Alkali Methods of Polychroming

Studies were made on the influence of time and temperature, of free access of air, of pH, of salt concentration, of evaporation and of various alkali salts as polychroming agents in the conversion of methylene blue into azures and other decomposition products. Extended spectrophotometric studies were made as a means of evaluating the rate of change and nature of final products, and staining tests were made as indicated.

Alkali polychroming of methylene blue proceeds equally well in the presence or absence of external oxygen. It is attended by a slow, continuous evolution of formaldehyde. It is accelerated by increase in concentration of alkali, by evaporation, by increase in pH, and by higher temperatures, but even the low pH levels and low alkali concentrations yield the same products if the process be continued long enough. This contrasts with the cessation of the polychroming on exhaustion of the oxidizing agent in the acid polychroming processes.

It is found that close control of pH, temperature, time, evaporation, access of air, and alkali concentration will enable the production on repeated trial of polychrome methylene blues which are spectroscopically and tinctorially closely similar. Nevertheless, spectroscopic control would appear to be indicated in manufacture.     

Buffered Romanowsky Staining of Collodion Coated Sections

It has been observed that when it is necessary to coat paraffin sections with collodion to prevent loss of parts of the sections or to prevent cell shrinkage, staining with the buffered Romanowsky technic¹ is often unsatisfactory. Under these conditions the azures generally stain well while the eosinophilic structures are tinged feebly or not at all with eosin. As the omission of accelerators had been found to give the same type of result², and as this defect had been remediable by increasing either the duration of staining or the concentration of dye, as well as by the use of accelerators, it was thought that increase either of staining time or of stain concentration might remedy the defect in the present instance as well.     

Reduction and azo coupling of quinones

Summary Cutaneous melanin in formol fixed skin and adrenochrome in dichromate fixed monkey adrenal after adequate bisulfite or dithonite reduction were found to give definite azo coupling reactions. Weaker reactions were obtained on unreduced material, and these disappeared on ferric chloride oxidation. Both cutaneous melanin and adrenochrome appear to exist in a quinhydrone status. Prolongation of dichromate treatment weakens or abolishes azo coupling capacity of adrenochrome. The findings support the concept of quinonization and reduction to prevent and restore azo coupling of enterochromaffin cells and noradrenaline islets of the adrenal.The most effective diazos for melanin werep-nitrodiazobenzene, fast black K and the diazosulfanilic acid, pH 1 pyronin B procedure, for adrenochrome. Diazosafranin and 2-chloro-4-nitrodiazobenzene were also useful. Blue and violet coupling products from toluidine blue and methylene violet RR fail to yield sufficient contrast to be convincing.