Teliospore Maturation in the Smut Fungus Sporisorium sorghi: An Ultrastructural Study Using Freeze Substitution Fixation

1991 ◽  
Vol 152 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Charles W. Mims ◽  
Karen M. Snetselaar
Keyword(s):  
Ultrastructural Study ◽  
Freeze Substitution ◽  
Smut Fungus

Ultrastructural study of the fission yeast Schizosaccharomyces pombe nucleolus by freeze substitution

1995 ◽  
Vol 84 (3) ◽  
pp. 228-228
Author(s):  
Leger Isabelle ◽  
Jacqueline Noaillac-Depeyre ◽  
Marie-Pierre Gulli ◽  
Michèle Caizergues-Ferrer ◽  
Nicole Gas
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Ultrastructural Study ◽  
Freeze Substitution

An ultrastructural study of nerve and glial cells by freeze-substitution

1980 ◽  
Vol 9 (2) ◽  
pp. 243-254 ◽  
Author(s):  
Nobutaka Hirokawa ◽  
Takaaki Kirino
Keyword(s):  
Glial Cells ◽  
Ultrastructural Study ◽  
Freeze Substitution

The spindle pole body cycle, meiosis, and basidial cytology of the smut fungus Microbotryum violaceum

1991 ◽  
Vol 69 (8) ◽  
pp. 1795-1803 ◽  
Author(s):  
Mary L. Berbee ◽  
Robert Bauer ◽  
F. Oberwinkler
Keyword(s):  
Spindle Pole Body ◽  
Freeze Substitution ◽  
Ustilago Maydis ◽  
Spindle Pole ◽  
Meiotic Spindle ◽  
Smut Fungus ◽  
Microbotryum Violaceum ◽  
Pole Body ◽  
Spindle Pole Bodies ◽  
Middle Piece

Freeze-substituted basidia of the smut fungus Microbotryum violaceum (Ustilaginales, Basidiomycotina) were examined electron microscopically with particular attention to the meiotic spindle pole body cycle and cytoplasmic characters of phylogenetic significance. Prophase basidia contained a subapical cluster of vesicles and tubules. During prophase, the spindle pole body consisted of two globular elements connected by a middle piece. The spindle pole body had an electron-opaque layer near the nucleus, and each globular element was bisected by an electron-opaque disk. The meiosis I spindle extended between two monoglobular, disc-containing spindle pole bodies. During interphase I and II, septa lacking pores divided the basidium between daughter nuclei. In interphase I, a putative new spindle pole body appeared between the nuclear envelope and the monoglobular spindle pole body residual from the first division. In meiosis II, a spindle was again established between two monoglobular spindle pole bodies, each of which again contained an electron-opaque disc. The cytoplasmic characters of M. violaceum are compared with those of Ustilago maydis and Sphacelotheca polygoni-serrulati. Key words: Microbotryum violaceum, basidiomycete, Ustilaginales, spindle pole body, freeze-substitution, ultrastructure.

An ultrastructural study of ascospore delimitation and maturation in Ascodesmis nigricana using freeze substitution fixation

1990 ◽  
Vol 48 (3) ◽  
pp. 630-631
Author(s):  
C. W. Mints ◽  
E. A. Richardson ◽  
J. Kimbrough
Keyword(s):  
Ultrastructural Study ◽  
Freeze Substitution ◽  
Chemical Fixation ◽  
Dialysis Membrane ◽  
Liquid Propane

Fungi belonging to the class Ascomycetes are characterized by the production of sexually derived spores termed ascospores inside a microscopic, sac-like structure termed an ascus. In the Euascomycetidae, typically uninucleate spore initials are delimited within the ascus as the result of the invagination of membranes that arise from the so-called "ascus vesicle", a discontinuous cylinder of two closely spaced unit membranes that develops around the extreme periphery of the ascus. To date, there are conflicting data regarding the origin of the ascus vesicle. We therefore decided to address the problem using freeze substitution fixation. The advantages of this procedure over conventional chemical fixation protocols for preservation of ultrastructural details in fungi have been well-documented. In this study small pieces of dialysis membrane bearing developing ascocarps of Ascodesmis nigricans were plunged into liquid propane and processed for TEM according to the procedures of Hoch and Mints et al.

Ca-Histochemistry in slime mold plasmodia

1978 ◽  
Vol 36 (2) ◽  
pp. 130-131
Author(s):  
Ulrich Dierkes
Keyword(s):  
Physarum Polycephalum ◽  
Carbon Coating ◽  
Freeze Drying ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
Uranyl Acetate ◽  
Slime Mold ◽  
Staining Procedure ◽  
Protoplasmic Streaming ◽  
Intracellular Ca

Calcium is supposed to play an important role in the control of protoplasmic streaming in slime mold plasmodia. The motive force for protoplasmic streaming is generated by the interaction of actin and myosin. This contraction is supposed to be controlled by intracellular Ca-fluxes similar to the triggering system in skeleton muscle. The histochemical localisation of calcium however is problematic because of the possible diffusion artifacts especially in aquous media.To evaluate this problem calcium localisation was studied in small pieces of shock frozen (liquid propane at -189°C) plasmodial strands of Physarum polycephalum, which were further processed with 3 different methods: 1) freeze substitution in ethanol at -75°C, staining in 100% ethanol with 1% uranyl acetate, and embedding in styrene-methacrylate. For comparison the staining procedure was omitted in some preparations. 2)Freeze drying at about -95°C, followed by immersion with 100% ethanol containing 1% uranyl acetate, and embedding. 3) Freeze fracture, carbon coating and SEM investigation at temperatures below -100° C.

Electron microscopic studies on ultrathin frozen sections of lactating mouse mammary gland

1978 ◽  
Vol 36 (2) ◽  
pp. 46-47
Author(s):  
Jan Zarzycki ◽  
Joseph Szroeder
Keyword(s):  
Mammary Gland ◽  
Protein Denaturation ◽  
Chemical Constituents ◽  
Freeze Substitution ◽  
Electron Microscopic Examination ◽  
Mouse Mammary Gland ◽  
Electron Microscopic ◽  
Preparation Methods ◽  
Microscopic Studies ◽  
Ultrathin Frozen Sections

The mammary gland ultrastructure in various functional states is the object of our investigations. The material prepared for electron microscopic examination by the conventional chemical methods has several limitations, the most important are the protein denaturation processes and the loss of large amounts of chemical constituents from the cells. In relevance to this,one can't be sure about a degree the observed images are adequate to the realy ultrastructure of a living cell. To avoid the disadvantages of the chemical preparation methods,some autors worked out alternative physical methods based on tissue freezing / freeze-drying, freeze-substitution, freeze-eatching techniqs/; actually the technique of cryoultraraicrotomy,i,e.cutting ultrathin sections from deep frozen specimens is assented as a complete alternative method. According to the limitations of the routine plastic embbeding methods we were interested to analize the mammary gland ultrastructure during lactation by the cryoultramicrotomy method.

Tumor Diagnosis

1982 ◽  
Vol 40 ◽  
pp. 262-265
Author(s):  
Bruce Mackay
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Differential Diagnosis ◽  
Light Microscopy ◽  
Clinical Examination ◽  
Ultrastructural Study ◽  
Diagnostic Procedures ◽  
Specific Diagnosis ◽  
Transmission Electron ◽  
Microscopic Diagnosis

The broadest application of transmission electron microscopy (EM) in diagnostic medicine is the identification of tumors that cannot be classified by routine light microscopy. EM is useful in the evaluation of approximately 10% of human neoplasms, but the extent of its contribution varies considerably. It may provide a specific diagnosis that can not be reached by other means, but in contrast, the information obtained from ultrastructural study of some 10% of tumors does not significantly add to that available from light microscopy. Most cases fall somewhere between these two extremes: EM may correct a light microscopic diagnosis, or serve to narrow a differential diagnosis by excluding some of the possibilities considered by light microscopy. It is particularly important to correlate the EM findings with data from light microscopy, clinical examination, and other diagnostic procedures.

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