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Journal ArticleDOI

Über das Antherentapetum mit besonderer Berücksichtigung seiner Kernzahl

01 Feb 1954-Vol. 101, Iss: 1, pp 1-63
TL;DR: In der vorliegenden Arbeit wurden zur Prufung der jungst aufgeworfenen Frage, ob dem Vorkommen des einkernigen Tapetums eine gewisse systematischen Bedeutung zukame, nicht nur die Angaben uber das Einkernige Tapetum (vgl. die Zusammenstellung S. 15−17) kritisch gesichtet, sondern auch alle Angabens uber e
Abstract: Da in den letzten Jahren die Beobachtungen uber ein einkerniges Tapetum weiter zugenommen haben, liegt die Vermutung nahe, das dieses eine weitere Verbreitung hat, als bisher angenommen wurde. In der vorliegenden Arbeit wurden zur Prufung der jungst aufgeworfenen Frage, ob dem Vorkommen des einkernigen Tapetums eine gewisse systematische Bedeutung zukame, nicht nur die Angaben uber das einkernige Tapetum (vgl. die Zusammenstellung S. 15–17) kritisch gesichtet, sondern auch alle Angaben uber ein mehrkerniges Tapetum gesammelt und beide Vorkommen einander gegenubergestellt (vgl. den systematischen Teil). Es schien auch angezeigt, auf die verschiedenartigen Abweichungen von der normalen Tapetumentwicklung hinzuweisen, da in einzelnen solchen Fallen (bei weiblichen Pflanzen und pollensterilen Apomikten) ein Unterbleiben oder Verzogern von Kernteilungen in den Tapetumzellen beobachtet werden konnte, wodurch eine Einkernigkeit vorgetauscht sein kann. — Das Vorhandensein sowohl eines inneren als auch eines mehrschichtigen Tapetums ist in den vorliegenden Fallen nicht an eine bestimmte Kernzahl geknupft.
Citations
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Journal ArticleDOI
TL;DR: A hypothetical phylogenesis of the tapetum is proposed on the basis of its morphological appearance and of the nutritional relations with meiocytes/spores, and the evolutionary trends of thetapeta tend towards a more and more intimate and increasingly greater contact with the spores/pollen grains.
Abstract: It appears that the tapetum is universally present in land plants, even though it is sometimes difficult to recognize, because it serves mostly as a tissue for meiocyte/spore nutrition. In addition to this main function, the tapetum has other functions, namely the production of the locular fluid, the production and release of callase, the conveying of P.A.S. positive material towards the loculus, the formation of exine precursors, viscin threads and orbicules (= Ubisch bodies), the production of sporophytic proteins and enzymes, and of pollenkitt/tryphine. Not all these functions are present in all land plants:Embryophyta. Two main tapetal types are usually distinguished in theSpermatophyta: the secretory or parietal type and the amoeboid or periplasmodial type; in lower groups, however, other types may be recognized, with greater or lesser differences. A hypothetical phylogenesis of the tapetum is proposed on the basis of its morphological appearance and of the nutritional relations with meiocytes/spores. The evolutionary trends of the tapeta tend towards a more and more intimate and increasingly greater contact with the spores/pollen grains. Three evolutionary trends can be recognized: 1) an intrusion of the tapetal cells between the spores, 2) a loss of tapetal cell walls, and 3) increasing nutrition through direct contact in narrow anthers.

346 citations

Book ChapterDOI
01 Jan 1984
TL;DR: After more than 30 years of research on the nuclear cytology of differentiated tissues, it is now clear that the “supernumerary chromonemal reproduction” at interphase, better called “chromosome endoreduplication” (Levan and Hauschka 1953), is the commonest and most widespread process of cell polyploidization in both plants and animals.
Abstract: In the older literature on angiosperm morphology many examples of very large cells with giant or “hypertrophied” nuclei within differentiated tissues, including reproductive tissues, have been reported, and the connection between nuclear size and trophic activity of the cell has been stressed (references in Schnarf 1929, Tischler 1944, Maheshwari 1950). Goldstein (1928) even attempted to establish a correlation between nuclear form and functional activities of normal and pathological cells. In the absence of adequate knowledge of the mechanisms responsible for the multiplication of the genome, the large size and the variable form (irregular, crenate, lobate, constricted, furrowed, etc.) of nuclei were generally assumed to result from fusion of nuclei and/or amitosis. The significance of restitutional mitosis as a mechanism of doubling the chromosome number was not realized, and was generally regarded as a pathological process. The situation began to change in the late 1930’s—early 1940’s following the discovery of endomitosis in Homoptera, e.g., the pondskaters of the genus Gerris (Geitler 1939), and the proposition that the tetraploid mitoses “with paired chromosomes” (now called “diplochromosomes”) in poly somatic root tips of Spinacia oleracea are due to a double chromosome reproduction at interphase (Berger 1941). After more than 30 years of research on the nuclear cytology of differentiated tissues, it is now clear that the “supernumerary chromonemal reproduction” at interphase (Lorz 1947), better called “chromosome endoreduplication” (Levan and Hauschka 1953), is the commonest and most widespread process of cell polyploidization in both plants and animals (Brodsky and Uryvaeva 1977, D’Amato 1977 a, Nagl 1978).

178 citations

Journal ArticleDOI
I.K. Vasil1
TL;DR: This article is restricted to a summary, discussion and evaluation of the knowledge of the physiology and cytology of anther development, particularly the role of tapetum and the development of pollen grains.
Abstract: An understanding of the morphology and physiology of the angiosperm flower and its component parts is of considerable importance in programmes for the development of new agricultural and horticultural varieties, in the elucidation of various hereditary processes and their control, and for an insight into various problems of cell biology, cell division and the physiology and control of reproduction. A great deal of work has been produced since the days of Amici (1824) and Hofmeister (I 848) regarding the developmental aspects of reproductive parts of the angiosperm flower, fertilization and the development of endosperm and embryo leading to the formation of a mature seed. Much of this work is summarized in the books by Schnarf (1929, 1931), and Maheshwari (1950, 1963). Unfortunately, very little effort, if any, has been made to understand the physiology of the reproductive organs of the angiosperm flower, particularly the chemical and cytochemical changes involved in the initiation and control of these processes (Vasil, 1965). The ultrastructural studies made by Rosen, Gawlik, Dashek & Siegesmung (1964) and by Sassen (1964) of the pollen tubes, by Heslop-Harrison (1962, 1963b, 1964) of the developing anther, and by Jensen (1963) of the embryo sac, fertilization and embryogenesis are, therefore, especially welcome. Some work has also been done recently on the histochemical and biochemical aspects of reproduction in higher plants (Linskens, 1 9 6 4 ~ ) . In order to limit the field of discussion and because of my own interest and familiarity with the angiosperm anther, this article is restricted to a summary, discussion and evaluation of our knowledge of the physiology and cytology of anther development, particularly the role of tapetum and the development of pollen grains." Discussion of the various aspects of the physiology of pollen grains after dehiscence is excluded as

123 citations

Journal ArticleDOI

111 citations

Journal ArticleDOI
TL;DR: The distribution of tapetal types in basal angiosperms is reviewed both from the literature and new observations in the context of recent phylogenetic analyses, finding apparent plasticity for a relatively brief but critical time in angiosperm evolution.
Abstract: The distribution of tapetal types in basal angiosperms is reviewed both from the literature and new observations in the context of recent phylogenetic analyses. Secretory tapeta predominate among land plants. The majority of basal angiosperms share a secretory tapetum with their anthophyte ancestors. Plasmodial and invasive tapeta are relatively rare in eudicots but have evolved several times among early‐branching angiosperms, especially in monocotyledons, in which they have evolved three or more times. The invasive tapetum has evolved at least four other times independently in basal angiosperms: in Nymphaeaceae, Annonaceae, Monimiaceae, and Winteraceae. Plasmodial tapeta are mostly found in monocotyledons but have evolved at least twice in basal angiosperms, in Annonaceae, and in Hernandiaceae/Lauraceae. This apparent plasticity for a relatively brief but critical time in angiosperm evolution may reflect the early evolution of highly specific pollination syndromes.

82 citations

References
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Journal ArticleDOI
TL;DR: Polyploidy and other irregularities in the maturation division indicate that these species may be hybrids, andMegasporogenesis and embryo sac development appear to be rather typical for the Gramineae.
Abstract: 1. Bromus marginatus and B. rubens are octoploid and tetraploid respectively; B. villosus is variable between octoploid and decaploid. 2. Polyploidy and other irregularities in the maturation division indicate that these species may be hybrids. 3. Lagging bivalents are found in B. villosus and B. marginatus. An irregular homeotypic division, showing much lagging and extrusion, occurs in B. villosus. 4. Varying types of chromatin extrusion are found in all three species, together with polycary and sterile pollen. 5. No examples of cytomyxis were observed. 6. Megasporogenesis and embryo sac development appear to be rather typical for the Gramineae. 7. Antipodals generally vary in number from five to eight, with a maximum of ten seen in one instance. Their nuclei are large, are often organized into cells, and finally occupy a lateral position just below the center of the sac, in which position they undergo dissolution, after an existence considerably longer than that characteristic of smaller cells.

18 citations

Journal ArticleDOI
TL;DR: The development of the sporangia in the Asclepiadaceae studied is the same in general as in other plants, while there are no indications of the phylogenetic history of the reduction in number.
Abstract: The development of the sporangia in the Asclepiadaceae studied is the same in general as in other plants, while there are no indications of the phylogenetic history of the reduction in number. The primary sporogenous cells without further division become the pollen mother cells. The latter divide each into four with the usual phenomena accompanying tetrad division, but through mutual adjustment and the close adherence of the microspores the evidences of grouping are lost.

17 citations

Journal ArticleDOI
TL;DR: The Carnoy mixture was perhaps the most useful in every respect as a killing agent, and gave very satisfactory results in studying Spiraea salicifolia.
Abstract: THE material used in preparing this paper was obtained largely from the Washington Park greenhouse, Chicago. Specimens of Spiraea salicifolia in various stages of development were secured from Grand crossing and East Chicago, Illinois, and from Marquette, Michigan. The species chosen for study was Spiraea Y7aponica, and this was supplemented by S. astilboides planidora and S. salicifolia. Specimens were killed. in chromacetic acid, Carnoy's mixture, and Flemming's mixture. All material was imbedded in paraffin, cut in serial sections with a microtome, and stained on the slide. Delafield's haematoxvlin alone or in combination with erythrosin or iron alum was used chiefly, but cyanin and erythrosin, or the safranin, gentian-violet, orange G combination were used in certain cases. The Carnoy mixture was perhaps the most useful in every respect as a killing agent, and gave very satisfactory results.

16 citations

Journal ArticleDOI
TL;DR: The account here presented is based entirely on the study of a white-spine variety of the cucumber, Cucumis sativus L., known as "Burpee's No. 38I, Arlington," which was secured from plants grown in the greenhouse at Purdue University in the autumn and winter of I923-I924.
Abstract: The account here presented is based entirely on the study of a white-spine variety of the cucumber, Cucumis sativus L., known as "Burpee's No. 38I, Arlington." Seeds were obtained from the grower in I923 and I924. Abundant material for this study, and also for a cytological investigation, was secured from plants grown in the greenhouse at Purdue University in the autumn and winter of I923-I924. Additional material was grown in the botanical greenhouse at the University of Wisconsin in the summer and autumn of I924 and the spring of I925. A few plants were grown outdoors. Material was fixed in several fixing solutions. Schaffner's chrom-acetic and Flemming's medium chrom-osmo-acetic fixatives proved to be the most satisfactory. Whole staminate inflorescences of various ages were fixed, as well as individual staminate flowers. Inflorescences and individual flowers are very pubescent, and for this reason offer difficulty in fixation. An air pump was used to remove the air bubbles in the case of inflorescences and also of some individual flowers. Very satisfactory results were also secured by treating individual staminate flowers as follows: after severing a flower from the plant, it was placed under a dissecting lens, and there, with the use of a needle and scalpel, the hairs were removed from the whole perianth tube. A few scraping strokes of the scalpel easily accomplishes this. Then, after cutting off the pedicel very close to the base of the receptacle, and in most cases also removing the perianth at about the base of the calyx lobes, the clean-shaven portion was immersed in the fixing solution. In most cases sinking took place in a short time. The material was dehydrated, cleared in chloroform, and further treated according to the usual paraffin method. Sections were cut from 4 u to 25 ,u in thickness and stained in safranin and Delafield's haematoxylin, Flemming's triple stain, and Haidenhain's iron-alum haematoxylin. Some nearly mature staminate flowers were studied by hand dissection. [The Journal for April (I4: I69-226) was issued April 26, 1927.] 227

16 citations