Studies of indophenol blue synthesis. I. The role of free radical formation by heart muscle particulates during the "G" Nadi reaction

A study of the "G" Nadi reaction mediated by Keilin and Hartree beef heart muscle preparations has revealed that of the two Nadi reagents, i.e., dimethylparaphenylenediamine and α-naphthol, only the diamine is enzymatically oxidized by the terminal respiratory enzymes of the heart particulates. In both spectrophotometric and manometric experiments, enzymatic oxidation of α-naphthol by the heart muscle enzymes could not be detected. Oxidation of the diamine resulted in formation of a stable free radical and polymers with characteristic absorption spectra. The free radical and polymers, upon formation, rapidly reacted with the α-naphthol in a non-enzymatic oxidative coupling to form indophenol blue. Incubation of dimethylparaphenylenediamine alone with heart muscle particles resulted in production of an insoluble blue dye in the particles. Upon extraction with 95% ethanol, the pigment, which is not indophenol blue, exhibited a broad absorption maximum at 460-470 mµ.

Silver impregnation of ultrathin sections for electron microscopy

A new procedure is described for silver impregnation of thin sections for electron microscopy. Sections of various tissues, fixed in OsO₄ and embedded in methacrylate, were treated with an ammoniacal silver solution, directly or after oxidation with periodic acid or hydrogen peroxide. After OsO₄ fixation all cellular membranous systems exhibit a primary argentaffinity probably due to the reduction of ammoniacal silver solution by the reduced osmium bound to unsaturated lipids. Bleaching the sections with hydrogen peroxide removes the argentaffinity of protoplasmic structures. Treatment of the sections with periodic acid results in decreased argentaffinity of protoplasmic components while the argentaffinity of metaplasmic structures is greatly enhanced. The latter procedure appears particularly useful for enhancing the contrast of basement membranes.

An evaluation of methods commonly used for the fixation and staining of glycogen

Blocks of liver from eight one-month-old Sprague Dawley rats were fixed in the following fixatives: 10% neutral formalin, 10% formalin, formol-saline, alcohol formalin, acetic alcohol formalin, Bouin's, Carnoy's and Rossman's for the following times: 24 hours,48 hours, seven days, two weeks, one month and three months. Sections were cut from these specimens and stained for glycogen by the periodic acid Schiff reaction and the Best carmine method.

It is concluded from these experiments that if the tissues are fixed in acetic alcohol formalin, then consistently good demonstration of glycogen will be obtained with the periodic acid Schiff stain, in livers stored in this fixative up to three months. Nearly as good results can also be obtained with the Best carmine stain, if the tissues are similarly fixed in Bouin's. Aqueous based fixatives cannot be relied upon after 24 hours to 48 hours to demonstrate the maximum amount of glycogen in tissues.

The phenomena of polarization is discussed and it was shown that acetic alcohol formalin fixed tissues gave the most marked polarization, whilst sections taken from specimens fixed in the aqueous based fixatives show considerably less polarization, and in some cases none at all.

Alcohol based fixatives give a coarser and larger granule of glycogen which stains with more vividness, and is easier to recognize following the periodic acid Schiff reaction than the Best carmine.

An unusual distribution of glycogen was observed with the two stains that were used. With the periodic acid Schiff reaction, some sections showed a very marked heavy peripheral accumulation of glycogen within the cells, whilst with the Best carmine method some sections showed a glycogen free peripheral zone. They were consistently reproduced but no suitable explanation can be offered for these observations.

Transient, focal accumulation of axonal mitochondria during the early stages of wallerian degeneration

Wallerian degeneration was produced in guinea pig sciatic nerves by a crush injury. At intervals of 2, 12, 24, 36, 48, 72, and 96 hours after the crush, the nerves were fixed in osmium tetroxide, and blocks from the distal, degenerating segment identified topographically prior to embedding in Araldite or Epon. Phase and electron microscopic study of serial cross- and longitudinal sections reveals a striking, localized accumulation of axonal mitochondria which precedes or accompanies the swelling and fragmentation previously reported by others. These focal accumulations of mitochondria are transient and are most frequently observed in the paranodal axoplasm of large myelinated fibers 24 to 36 hours after crush injury, but are also occasionally identified in small myelinated fibers and unmyelinated axons. Migration and proliferation of axonal mitochondria are considered as possible explanations of these observations.

Electron microscope replicas from the surface of a fracture through frozen cells

A technique is described, which is new in certain details, for fracturing frozen cells and taking replicas from the fracture surface. This technique has been developed as a cytological preparative technique complementary to those currently used in electron microscopy. The present paper describes results for human red cells, chosen for preliminary work to facilitate recognition of artifacts. The cells are suspended in 20 per cent glycerol, 0.9 per cent NaCl solution, allowed time to equilibrate, and rapidly frozen in a small chamber plunged into propane at -196 degrees C. The chamber is kept at -196 degrees C., and fractured in vacuo, in such a way that the fracture plane runs through the frozen suspension, and through the cells in its path. After fracture, the chamber is brought to -105 degrees C., still in vacuo, to etch the fracture surface, and a platinum-carbon replica is deposited on the surface from a carbon arc. The replica is subsequently cleaned in concentrated alkaline solution and examined in the electron microscope. The outlines of the fractured cells can be recognised. There are indications that in areas of the replica which correspond to the interior of a cell, individual haemoglobin molecules can be seen, and in favourable cases the arrangement of some of the four molecular subunits.

Histochemical demonstration of specific phosphatases of the liver preserved in hypertonic sucrose solution

The observation of Holt that the storage of formalin fixed tissues in sucrose-gum acacia solution preserves acid phosphatase activity was confirmed. The same was found for 5-nucleotidase. Adenosinetriphosphatase activity is present after storage both in formalin and in sucrose-gum acacia solution. However, the staining for acid phosphatase activity after preservation in sucrose and for adenosinetriphosphatase activity after preservation in formalin and in sucrose solution revealed artefacts decreasing the usefulness of this procedure for routine application.

Preparation of naphthol AS-TR phosphate for localization of phosphatase

The use of PCl5 in dioxan for the conversion of Naphthol AS-TR to the acid phosphate, even without the addition of catalysts other than pyridine, gave a conversion considerably superior to that obtained using POCl3 in either tetra-hydrofuran or dioxan, with or without the additional catalysts suggested by Burstone. The product proved satisfactory for histochemical localization of alkaline phosphatase in bone, though it is suspected that a certain amount of polymerization had occurred in the process of phosphorylation.

Studies of acute phase protein. I. An immunohistochemical method for the localization of Cx-reactive protein in rabbits. Association with necrosis in local inflammatory lesions

A method is presented for the immunohistochemical localization of Cx-reactive protein in rabbits, based on the use of a defined antiserum and rigorous fixation techniques requisite for this antigen. In animals in which inflammatory lesions and CxRP response were induced by intramuscular injection of typhoid vaccine, Cx-reactive protein was localized only in the area of local inflammation within muscle fibers showing morphologic evidence of necrotic change. Within such altered fibers, CxRP was observed in peripheral segments of myofiber or in subsarcolemmal sarcoplasm, in scattered deposits in sarcoplasm, and in vacuolar inclusions. No CxRP was found at any time in polymorphonuclear or mononuclear cells in the inflammatory lesion, nor in contralateral muscle, regional or distal lymph nodes, liver, spleen, thymus, heart, or kidney, except as traces in lumens of vessels or interstitium. CxRP was first detected in necrotic myofibers at the inflammatory site after a latent period of 8 to 10 hours following injection of the inflammatory stimulus and could be demonstrated in these sites for the 48 hours of the experiment. It could not be observed at the inflammatory site before appearance in the blood. Identical histologic localization in necrotic myofibers at the site of the local lesions was found following induction of granulocytopenia with nitrogen mustard. These findings are consistent with the hypothesis that CxRP is formed locally at the site of inflammation from tissue elements undergoing necrotic change. Alternatively, secondary deposition from the blood at the inflammatory site cannot be excluded, but is considered less likely in view of the failure to obtain evidence of a cellular localization of CxRP in other organs.

The use of sodium chloride-containing fixatives in minimizing cellular distortion in histological and cytochemical preparations

The principal objective of this study was to determine the relative effect of the concentration of small, mobile ions in fixing solutions on cellular shrinkage and distortion occurring during fixation or in the subsequent processing of tissues by the paraffin method.

Samples of rat liver tissue were fixed in neutral 20% formalin, neutral 20% formalin/0.7% sodium chloride, Bouin's fluid, and Bouin's fluid/0.7% sodium chloride. By a comparison of nuclear and cytoplasmic volumes, it was noted that in the case of formalin fixation, the addition of 0.7% sodium chloride reduced nuclear and cytoplasmic shrinkage by 18-26%. In Bouin fixation the addition of 0.7% sodium chloride reduced nuclear shrinkage by 7-10% and cytoplasmic shrinkage by approximately 21%.

It was also shown that when the sodium chloride is omitted, neutral 20% formalin is significantly less effective than Boumin's fluid in stabilizing the cytoplasm of liver parenchymal cells against shrinkage.

In those instances in which tissue shrinkage was minimized by the addition of sodium chloride to the fixing medium, the final preparations revealed less tissue distortion and a more adequate preservation of fine detail. Some mention is also made of differences incurred in staining reactions of liver tissue following the use of sodium chloride containing fixatives.

Applications of freeze-substitution to electron microscope studies of invertebrate oocytes

A modified freeze-substitution process is described which gives a low percentage (less than 5 per cent) of preparations of invertebrate eggs which appear to be ice crystal-free at the resolution of the electron microscope. The mitochondria show no membranes in these preparations but can be recognized by internal spaces with the size and the distribution of the cristae. The Golgi bodies resemble those seen with diffusion fixatives, but the limiting membranes are here double; that is, they appear to be a triple-layered sandwich with two outer dark approximately 25A layers and an inner light layer of the same thickness. The endoplasmic reticulum is clearly present and resembles that seen with diffusion fixatives. Here again, the limiting membranes are double with the same dimensions as those in the Golgi bodies. The membranes of the Golgi bodies and ER are seen after permanganate but not lead hydroxide staining. The hyaloplasm (or "cell sap") is crowded with 150 to 200A particles and these are also seen lining the ER membranes. In general, the structures as seen with the present technique show considerable similarity to those seen with diffusion fixatives.

Quantitation of periodic acid-Schiff positive substances using radioactive Schiff reagent

A simple method is described which makes it possible to determine the relative amount of Schiff reagent bound to periodic acid oxidized tissue sections. It is based on the application of S35-labeled Schiff reagent. It was found that paraffin embedded tissue sections bind significant amounts of Schiff reagent without any previous treatment, but using appropriate control sections it is possible to determine the relative amounts of aldehyde groups created by periodic acid oxidation as opposed to the amounts in the controls.

Fixation of neural tissues for electron microscopy by perfusion with solutions of osmium tetroxide

This paper describes in detail a method for obtaining nearly uniform fixation of the nervous system by vascular perfusion with solutions of osmium tetroxide. Criteria are given for evaluating the degree of success achieved in the preservation of all the cellular components of the nervous system. The method permits analysis of the structural relations between cells at the electron microscopic level to an extent that has not been possible heretofore.

Polyester-methacrylate embedments for electron microscopy

It has been found that tissues fixed for electron microscopy and dehydrated in acetone can be embedded in mixtures of n-butyl methacrylate and polyester resin. Activation with 1 per cent tert-butyl hydroperoxide followed by 12 to 48 hours at 60 degrees C produces blocks that section well with glass knives. The ribbons are cleared of methacrylate by heat (200-250 degrees C for 1 hour) and/or immersion in organic solvents (CCL(4), acetone-ether). After removal of the methacrylate the residual polyester matrix provides thermostable and insoluble support for the tissue. Its insolubility permits staining by immersion of cleared preparations in organic solvents carrying heavy metal compounds in solution. Clearing by heat stabilizes section-grid relationships. The removal of volatile materials by clearing substantially reduces contamination of both specimen and microscope. Tissue fine structure is well preserved in these preparations.

Improvements in epoxy resin embedding methods

Epoxy embedding methods of Glauert and Kushida have been modified so as to yield rapid, reproducible, and convenient embedding methods for electron microscopy. The sections are robust and tissue damage is less than with methacrylate embedding.

Some electron microscopical observations on liquid-crystalline phases in lipid-water systems

OsO(4) fixation preserves some liquid-crystalline phases of soaps and phospholipids to an extent that it is possible to observe their structure in electron micrographs of thin sections. Good agreement exists between the structure observed directly and that deduced from x-ray diffraction studies of the same systems.