The mechanism accounted for the silver staining "fast techniques" development and its histochemical meaning. II. The binding between silver and ferric ion accounted for the silver staining development.

Results obtained on filter paper strips models show that some protein and fatty acids become argentophil as an effect of a previously binding ferric ion although, in this instance, the silver staining can only be accomplished by using a silver diamine solution, since a silver nitrate solution is not effective. However, if the filter paper model is previously treated by a "multidentate ligand" before the silver nitrate solution treatment becomes able in doing the silver staining. This result shows that the binding between Fe3+ and Ag+ can be done if a suitable negatively charged "multidentate ligand" has been connected between them. The following "multidentate ligands" were tested: thiocarbohydrazide, carbohydrazide, and hexamethylenetetramine: ammonia was also tested, as an attempt to disclose if it is able to act as a "multidentate ligand". The semicarbazide effect was analysed and compared with the "ligands". It was found, either on filter paper strip models or on histological sections, that every "multidentate ligand", as well as ammonia, are effective in producing silver staining whereas semicarbazide is devoid of effect. The "ligands" effectiveness depends upon the solution pH, in the same manner that is does occur when the silver diamine "fast technique" is used on tissue sections. Histophotometric measures, taken on tissue sections, show that the silver staining afforded by the silver diamine "fast technique" is similar to that displayed by the "multidentate ligand" plus a silver nitrate solution treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

The mechanism accounted for the silver staining "fast technique" development and its histochemical meaning: I. The correlation between the silver staining intensity and the tissue bound ferric ion and some other tissue histochemical reactivities.

The mechanism accounted to accomplish the silver staining "fast technique" on tissues sections was studied towards the correlation among histophotometric measures concerning the silver staining intensity and the intensity provided by some histochemical reactions performed on spleen and liver sections from rats and pigs. By treating previously these histological sections with thioglycolate or oxalate solutions in progressive concentrations and afterwards subjecting them to a silver staining "fast technique", it was demonstrated that the silver staining intensity decreases proportionally to the thioglycolate or the oxalate solution concentration. The regression line of the silver staining intensity on the thioglycolate or the oxalate solution concentration was established, as well as its regression coefficient. On the other hand, on histological sections previously subjected to the thioglycolate or the oxalate treatment, some histochemical techniques were performed and the histophotometric measures concerning the intensity of each histochemical technique used were taken and its regression line, as well as its regression coefficient were established. By comparing the silver staining intensity regression line (or its regression coefficient) with the regression lines established for the histochemical techniques used, it was tested the correlation between the silver staining and the reactivity of some reactive groups contained into the tissues. In this manner, the influence of such reactive groups on the silver staining development was tested. The results show that there is no correlation between the silver staining intensity and the reactivity degree of the reducing groups (-SH- and carbonyl group), the 1-2-glycolic group, as well as of some protein reactive groups (phenol, imidazole, carboxylic groups). On the other hand, taking into account the respective regression lines and its regression coefficient, the comparison between the silver staining intensity and the Prussian blue reaction intensity shows a close relationship between them. This finding suggests that for the silver staining "fast technique" the tissue bound ferric ion accomplishes a very important role and can be accounted for its mechanism and its histochemical meaning.

Quantitative assay of Schieff and PAS reactivity during nerve degeneration in rats.

Quantative histochemical analysis of nerve degeneration in rats from zero to 192 hours was studied utilizing both Schiff reagent and PAS reaction. In addition, amylase digestion prior to PAS staining and aniline blockade of Schiff reactivity were employed. The staining intensity of all the reaction was measured histophotometrically and the mean optical density (OD) was determined for the following time intervals: 0, 24, 48, 96, and 192 hours.

Histochemistry of the amyloid substance from familial amyloidotic polyneuropathy.

The histochemical properties of the amyloid substance from familial amyloidotic polyneuropathy (FAP) were studied. The results showed differences among the FAP amyloid and the others amyloid substance. The main difference being that FAP amyloid substance was free of or only contain a small amount of protein. It contains acid and neutral glycidic substances, constituting its major part.