scispace - formally typeset
Search or ask a question
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
More filters
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
More filters
Journal ArticleDOI
01 Feb 1944

7 citations

Journal ArticleDOI
01 Jan 1939
TL;DR: In this paper, the development of the floral parts in Stachytarpheta indica has been studied and it has been shown that the calyx differentiates before the stamens and the petals.
Abstract: Organogeny of the flower and structure and development of the anther and embryo-sac have been studied in some members of the Verbenaceae. The development of the floral parts inStachytarpheta indica shows that the calyx differentiates before the stamens and the petals, and not after the stamens as has been described by Kanda (1923) inVerbena. Development of the anther and the pollen is quite normal. Cytokinesis takes place by furrowing. Tapetum is of the secretion type. The pollen grains are mostly spherical, but inStachytarpheta they are prominently three-lobed. The mature pollen grain is 3-nucleate. The ovule shows a single archesporial cell. No parietal cell is cut off and the archesporial cell directly develops into the megaspore-mother cell. A linear tetrad of megaspores is formed, of which the chalazal megaspore develops into the embryo-sac according to the normal type. The egg-apparatus has a normal structure and so is the behaviour of the polar nuclei. The antipodals are small and three in number, but inClerodendron Phlomidis they multiply by repeated divisions to form about twenty cells. The nucellus is of the typical sympetalous-type.

7 citations