Journal ArticleDOI
Meiosis in Coprinus lagopus: a comparative study with light and electron microscopy.
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Meiosis within fruiting bodies of Coprinus lagopus Fr.Abstract:
Meiosis within fruiting bodies of Coprinus lagopus Fr. is closely synchronized. This conveniently facilitates joint light- and electron-microscope observations. Before nuclear fusion the chromatin appears diffuse in the light microscope; after nuclear fusion individual chromosomes can be recognized. In the electron micrographs the chromatin of pre-fusion and early fusion nuclei cannot be recognized as defined structures with the fixation and staining procedures employed. At the time of synapsis the lateral components of the synaptinemal complexes can be seen in the micrographs. The pairing process of the two chromosomes of the homologous pairs is believed to involve two steps: (1) two homologous chromosomes become aligned in parallel, and (2) pairing occurs by formation of the synaptinemal complex including the central synaptic component. The term synaptic centre is coined for the central component, which is believed to be the zone where crossing-over occurs. The formation of this structure in relation to homologous pairing, and the structural organization of the synaptinemal complexes are discussed.
At meiotic metaphase, the chromosomes congregate around the central spindle microtubules. They are contracted and contain densely packed chromatin fibrils. Two types of spindle microtubules are demonstrated: (1) the chromosomal microtubules directly connecting the chromosomes to the centrosomes, and (2) the central spindle microtubules connecting the two centrosomes. The centrosomes are round, fibril-containing bodies approximately 0.3 µ in diameter. They have been observed outside the nuclear envelope at pachytene, but do not show the characteristic structure normally found in animal cells.read more
Citations
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Journal ArticleDOI
A low-viscosity epoxy resin embedding medium for electron microscopy.
TL;DR: A low-viscosity embedding medium based on ERL-4206 is recommended for use in electron microscopy and has a long pot life of several days and infiltrates readily because of its low viscosity.
Journal ArticleDOI
Life History and Developmental Processes in the Basidiomycete Coprinus cinereus
TL;DR: Coprinus cinereus has two main types of mycelia, the asexual monokaryon and the sexual dikaryon, formed by fusion of compatible monokARYons, and several genes involved in these processes have been identified.
Journal ArticleDOI
The Synaptinemal Complex
M Westergaard,D von Wettstein +1 more
TL;DR: The present review covers the three years 1968-1971 of the extensive work of Sotelo, R. Wett stein and coworkers and these articles will be�used as the main references to their work.
Book ChapterDOI
Variant mitoses in lower eukaryotes: indicators of the evolution of mitosis.
TL;DR: This chapter discusses the characteristics and evolution of mitosis, a types of nuclear division that produce two, or rarely more, daughter nuclei, each containing a chromosome complement approximately similar to that of the original nucleus.
Journal ArticleDOI
Spindles, spindle plaques, and meiosis in the yeast saccharomyces cerevisiae (hansen)
Peter B. Moens,Ellen W. Rapport +1 more
TL;DR: The intranuclear spindle of yeast has an electron-opaque body at each pole that lies on the nuclear envelope and each of the plaques at the poles of the spindle duplicates and the resulting side-by-side plaques increase in size.
References
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Preliminary Observations of the Chromosomes of Neurospora Crassa
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Journal ArticleDOI
The fine structure of chromosomes in the meiotic prophase of vertebrate spermatocytes
TL;DR: The prophase chromosomes of the first meiotic division in pigeon, cat, and man contain a central structure or core consisting of a pair of dense fibrils that are parallel to one another and equidistant from a delicate linear region of increased density midway between them.
Journal ArticleDOI
Chromosome morphology and the chromosome cycle in the ascus of neurospora crassa
Journal ArticleDOI
The ultrastructure of oogonia and oocytes in the foetal and neonatal rat
L. L. Franchi,Anita M. Mandl +1 more
TL;DR: Ovaries from eighty foetal and neonatal rats were examined under the electron microscope and patterns of degeneration (‘atretic divisions’, ‘Z’ cells and atresia at the diplotene phase), whose histological appearance and incidence have been recorded by Beaumont & Mandl (1962), were identified.
Journal ArticleDOI
The Relation between the Axial Complex of Meiotic Prophase Chromosomes and Chromosome Pairing in a Salamander (Plethodon cinereus)
TL;DR: An investigation of the structure of meiotic chromosomes from primary spermatocytes of two salamanders, Plethodon cinereus and Desmognathus fusca, has been made using correlated light and electron microscopy.
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