Fine structure in ascosporogenesis of freeze-substituted Arthroderma simii (original) (raw)
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Fine structure of ascosporogenesis in Ceratocystiopsis proteae
Canadian Journal of Botany, 1993
VAN WYK, P.W.J., and WINGFIELD, M.J. 1993. Fine structure of ascosporogenesis in Ceratocystiopsis proteae. Can. J . Bot. 71: 1212-1218. The development and ultrastructure of the ascoma, asci, and ascospores in Ceratocystiopsis proteae were studied and compared with that of other genera in Ceratocystis sensu lato. Ascospore delimitation commenced with the formation of double delimiting membranes in the ascus as is true in other species in Ceratocystis s.1. The ascospore wall developed between these membranes. In contrast with three wall layers observed in other species, only two wall layers were observed in C. proteae. Falcate sheaths previously reported in light-microscopic studies were not observed. The falcate appearance of ascospores may be ascribed to the adherence of a matrix to the outermost wall layer during ascospores release. Differences between this species and others in Ceratocystis s.1. illustrate the problems that can arise from the use of single morphological characteristics in the taxonomy of this group. It is accordingly suggested that the genus Ceratocystiopsis requires taxonomic revision.
Ultrastructure of developing ascospores in Sordaria brevicollis
Journal of Bacteriology, 1976
The ultrastructure of ascospore wall formation in the pyrenomycete Sordaria brevicollis was studied in developing asci at progressive time intervals. From early spore delimitation through final stage of maturation, the wall of the ascospore differentiated into four composite layers, the periascosporium the delineation ascosporium, the subascosproium, and the endoascosproium, While ascospores were at the hyaline stage of development,they possessed only the periascosporium and delineation ascosporium as their wall components. At about 7 to 8 days from the initiation of the cross, the spores developed a yellow color, and this coloration was always associated with the elaboration of the subascorsporium just internal to the ascosporium. Asthe spores continued to progressively darken in color, the subascosporium was seen to increase in complexity, electron density, and thickness. Soon after the formation of the subascosporium, the endoascosporium began to develop de novo and was, therefor...
Ascospore development in Ophiostoma piceae
Canadian Journal of Botany, 1992
The development of ascoma, ascus, and ascospore in Ophiostotna piceae was studied ultrastructurally and compared with that of other Ascomycetes. Ascospore delimitation commenced with the formation of double delimiting membranes in the ascus. The ascospore wall, consisting of the primary and secondary walls, was deposited between these membranes. The elongate ascospores of 0 . piceae differed from other species having similarly shaped ascospores, with respect to the shape and arrangement of asci in the ascoma, the number of wall layers of the ascospore, and formation of the secondary wall. Asci in 0 . piceae are spindle shaped, arranged along the periphery of the ascomatal wall. The ascospores have three layered walls, whereas some other species in Ceratocystis s.1. also with elongated ascospores probably have only two wall layers.
Ascus structure and ascospore formation in the lichen-forming Chaenotheca chrysocephala (Caliciales)
1985
In the thin-walled pre-meiotic asci of Chaenotheca chrysocephala a peripheral ascospore delimiting membrane cylinder was formed by transformation of membrane material generated by the proliferating plasma membrane. The ascus wall broke in parts and was degraded soon after the onset of secondary ascospore wall formation. Numerous lysosomes were observed prior to ascus deliquescence. The ascospores grew and their secondary wall layer became melanized after their release into the mazaedium.
The Journal of Cell Biology, 1960
The fine structure of cells of Saccharomyces cerevisiae engaged in the formation of ascospores was studied in electron micrographs of ultrathin sections. Although the mode of the first reduction division could not be clearly determined, the second nuclear division appeared to proceed in a manner similar to that observed previously during vegetative division. That is, division by constriction of the existing nucleus occurs without dissolution of the nuclear membrane and without involvement of discrete chromosomes. Variously shaped areas of low electron density were discerned within the nucleoplasm; these had not been previously seen in the vegetative nucleus. The significance of this nuclear differentiation and its possible similarity to nuclear structures reported in bacteria and an imperfect fungus are discussed. The cytoplasmic membrane appears first in the developing ascospore. The formation of an outer coat and an inner coat then follows. The cytoplasmic vacuole was observed not...
Histological study on the body wall of Ascaridia galli
2009
The body wall of Ascaridia galli has been investigated using 1-2 µ thick sections and stained with Toludin Blue. It is found to consist of three layers, cuticle, hypodermis or subcuticle and muscle layer. The cuticle in turn consists of three layers namely cortex or upper layer deeply stained with TB, 1.7 µ in thickness, middle layer or matrix 3.15 µ in thickness with no distinct constitutions, then fiber layer which in turn consists of several layers of dense tissue, its thickness 5.65 µ and settled on basement membrane. On the surface of the cuticle plugs a transverse annuli which divide the body into annuli, the distance between each two 0.22 µ each annulus is divided by three subannuli, large anterior 0.124 µ in length and other two are small, middle and posterior 0.047-0.054, 0.045-0.054 µ respectively. The hypodermis or dermis is thin and not well developed and of syncytial type and its nuclei are constricted to the longitudinal cords that is, dorsal, ventral, and two laterals...