THE USE OF WATER-SOLUBLE GLYCOL METHACRYLATE IN ULTRASTRUCTURAL CYTOCHEMISTRY

Intracytoplasmic crystalloid structures in a malignant fibrous histiocytoma: ultrastructural and cytochemical study

Crystalloid structures were frequently observed in the cytoplasm of the tumor cells of a malignant fibrous histiocytoma arising in the left leg of a 71-year-old female. These structures were located in the cytoplasm of the fibroblastlike and histiocyte-like tumor cells. The structures consisted of an aggregate of dense granules without unit membrane. Neither glycoproteins nor polysaccharides were detected in these structures on sections stained with chromic acid-phosphotungstic acid or periodic acid-thiocarbohydrazide-silver proteinate. On sections from acrylate-embedded specimens, the structures were easily digested by trypsin and protease but were not sensitive to RNase. Although the significance and origin of these structures remain obscure, the results indicate that the crystalloid structures in the present study are mainly composed of proteinaceous substance.

Electron microscopic serial section analysis of nodes of Ranvier in lumbosacral spinal roots of the cat: ultrastructural organization of nodal compartments in fibres of different sizes

The general ultrastructural organization of nodes of Ranvier in peripheral nerve fibres from 2 to 20 microns in diameter (D) was investigated in the adult cat using serially sectioned ventral and dorsal spinal roots. The study was performed in order to collect and systematize information considered necessary for a morphometric analysis of the node of Ranvier. In all cases a node of Ranvier could be divided into a central nodal axon segment and a surrounding nodal Schwann cell compartment. The latter included a nodal gap matrix substance, more or less overlapping nodal Schwann cell collars and, as a rule, also a Schwann cell brush-border emanating from the nodal Schwann cell collars and occupying the nodal gap. The relative size and the organization level of the nodal Schwann cell compartment increased with increasing fibre size up to a fibre diameter of 8-10 microns. At this fibre size the nodal gap was of a fairly even height (1 micron) all around the nodal axon and contained a thick brush-border of densely packed, more or less radially arranged Schwann cell microvilli. In very small fibres (D less than 3 microns) the nodal gap was low (less than 0.1 microns) and contained no or few microvilli. In fibres greater than 10 microns in diameter the relative size and the degree of structural order of the nodal Schwann cell compartment decreased with increasing fibre size. Drastic sectorial variations in nodal gap height and local thinning-out of the brush-border became prominent features in the largest fibres. The possible in vivo organization of the nodal Schwann cell compartment is discussed. Preliminary calculations indicate that the extracellular space directly surrounding the nodal axon might be quite small and that the area open for free communication between this extracellular space and the endoneurial space might be very much restricted, measuring as little as 2% of the area of the nodal axolemma. Algorithms for calculating various nodal structural parameters are discussed.

Glycol methacrylate in light microscopy: nucleic acid cytochemistry

Techniques utilizing Feulgen, azure B bromide, methyl green-pyronin, gallocyanin chromalum and cresyl violet stains have been modified and adapted for visualizing nucleic acids in 0.5-2.0 micrometer sections of tissues embedded in glycol methacrylate (GMA). Methods for evaluating the stain specificity for DNA and RNA using deoxyribonuclease and ribonuclease digestions, aldehyde blocking, and acid extractions are also described. The specificity of the stains in GMA embedded tissues is comparable to that reported for paraffin-embedded tissues.

Methods in ultrastructural cytochemistry of the cell nucleus

The electron microscopical study of the cell nucleus as observed in thin sections requires the use of cytochemical methods because of the intricate pattern of the nuclear components. The in situ techniques based on electron staining and enzymatic digestion are reviewed, excluding autoradiography, cytoenzymology and immunocytochemistry. A tentative classification has been adopted according to the chemical nature of the revealed component. Thus, the staining procedures for the nucleoproteins in general, for both nucleic acids, for the proteins, and finally for the deoxyribonucleoproteins and DNA are considered separately. 1--Stains for the nucleoproteins include simple reagents such as the uranyl and lead salts which are largely used in electron microscopy but are of limited specificity. 2--A variety of methods, some of them specific, is available for the simultaneous visualization of DNA and RNA which is based on common properties: basophilia, ability to bind diaminoacridines, presence of hydroxyl groups. However, due to the recent development of specific and preferential methods for each nucleic acid, we feel that among the older methods, only rapid and simple procedures for the detection of both nucleic acids remain of interest. 3--Proteins being ubiquitous, the useful techniques must reveal subsets within the total nuclear proteins. Apart from some endogeneous enzymes, basic proteins -- practically histones -- so far represent the only group for the detection of which reliable methods exist. 4--Several techniques developed recently are available for the specific detection of DNA. In favourable cases, methods derived from the Feulgen reaction allow its visualization at a molecular level. In addition, standard procedures for the preparation of mammalian cells and tissues are described. Each staining method is at least briefly discussed, but emphasis has been placed on a small number of techniques described in detail. They comprise the EDTA regressive stain for the ribonucleoproteins, several reactions of the basic proteins and the Feulgen-like osmium ammine reaction for DNA.

An embedding method for histochemical studies of undecalcified skeletal growth plate

We have used glycol methacrylate to study undecalcified skeletal growth plate and subchondral bone. Minor modifications of the original technique including dehydration in glycol methacrylate vacuum infiltration and polymerization in the cold make it quite suitable for embedding of such tisssues. Moreover, specimens can be processed quickly and the morphologic and biochemical integrity of the tissue retained so that histochemical procedures can be readily applied. Collagen, glycosaminoglycan, glycogen, lipid, calcium and the activity of alkaline and acid phosphatase were localized. This technique appears to be very useful for studying skeletal tissues.

Enzyme histochemical investigation of glycol methacrylate embedded chick embryonic tissue

The advantages of the water-soluble glycol methacrylate (GMA) embedding procedure make it highly applicable for use with fragile early embryonic material. Not only can one obtain tissue sections containing excellent histological detail, but numerous enzymes are retained for subsequent histochemical localization. For the purpose of establishing a methodology whereby concomitant histology and histochemistry could be obtainable, various fixatives and fixation times have been evaluated on GMA embedded chick embryonic mesonephros and gonad. It was found that fixing the tissues for 1 h in a solution of 95% ethanol, 5% acetic acid and 10% neutral-buffered formalin resulted in the retention of not only excellent histology but also alkaline and acid phosphatase. Thus, with this procedure, more specific investigations of early embryonic tissue can be performed.

Ultrastructural nuclear changes of extranucleolar ribonucleoprotein structures during autolysis of normal liver cells

The ultrastructural changes of extranucleolar nuclear ribonucleoprotein structures during autolysis of normal liver cells were studied by means of usual and cytochemical procedures. The results revealed that the earliest changes were characterized by the fragmentation of the perichromatin fibrils and disappearance of the perichromatin granules. This was followed by the formation of numerous dense granules among the altered perichromatin fibrils and by the disappearance of dense fibrillar structures from the remaining interchromatin areas. In the later stages of autolysis the altered perichromatin fibrils loosed their density and the dense granules located among them disappeared. In addition, fine filamentous and cross-striated bodies appeared in the nucleoplasm as well as in the cytoplasm of some hepatocytes. The results obtained by the EDTA treatment and digestion of the sections with Pronase and RNA-ase indicated that the altered perichromatin fibrils contained ribonucleoprotein which together with that of the perichromatin granules represent nuclear components most sensitive to the autolysis. The chemical nature of the dense granules located among the altered perichromatin fibrils was different from that of the latter as well as from that of the nuclear microspherules [6]. The dense fine filamentous and cross-striated nucleoplasmic and cytoplasmic bodies are considered to represent a nonspecific structural phenomenon accompanying regressive cellular alterations since these bodies were present only in the later stages of autolysis.

The use of glycol methacrylate embedding for studies of chromatin distribution and fine structure in salmon spermatid nuclei

Glycol methacrylate has been used as an embedding medium for studies of spermiogenesis in the salmon. DNA and basic proteins are shown to stain with the same specificity in thick (0.5-1.0 mu) sections of GMA-embedded salmon testes as in sections of comparably fixed, paraffin-embedded testes. Stain can be localized far more precisely in GMA sections than in paraffin sections due to the thinness of the sections and to the excellent structural preservation of nuclei. In addition, ultra-thin sections of GMA-embedded salmon testes can be observed with the electron microscope, and this permits exact correlation between nuclear fine structure and chemical composition in consecutive sections of the same nuclei.

Acute leukaemia with eosinophilia or acute eosinophilic leukaemia: a dilemma

A young male patient is described with acute leukaemia whose bone marrow and peripheral blood contained abundant cells of the eosinophilic series in all stages of maturation. These cells, proven histochemically to be true eosinophils, were abnormal in both maturation and proliferation. Upon electron microscopic study of bone marrow and peripheral blood, abnormalities in the eosinophilic series were identified as early as the promyelocytic stage as well as in the most mature eosinophil seen. The clinical and morphologic picture of this patient's disease raises the possibility of this being an acute eosinophilic leukaemia.

Morphological and cytochemical studies on lymphocytic choriomeningitis virus

Lymphocytic choriomeningitis (LCM) virus was observed by electron microscopy in thin sections of infected tissue cultures. The particles were pleomorphic and varied greatly in size. The smaller particles (50 to 200 nm) appeared to be spherical, whereas the largest (over 200 nm) were often cup-shaped. All particles contained one to eight or more electron-dense granules which were removed by ribonuclease. The particles were formed by budding from the plasma membrane and appeared to have spikes. The morphological evidence suggests that LCM should be considered as belonging to the presently unclassified group of lipoprotein-enveloped ribonucleic acid viruses.