Enzymatic isolation of viable nucelli at the megaspore mother cell stage and in developing embryo sacs in Nicotiana tabacum

1993 ◽  
Vol 6 (3) ◽  
Author(s):  
Yan Wu ◽  
Chang Zhou ◽  
H.-Ulrich Koop
Keyword(s):  
Nicotiana Tabacum ◽  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Cell Stage ◽  
Enzymatic Isolation

Embryological studies in the compositae, I. Sporogenesis, Gametogenesis, and Embryogeny in Cotula australis (Less.) Hook. F

1962 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
GL Davis
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Embryo Sac ◽  
Subsequent Development ◽  
Pollen Grains ◽  
Archesporial Cell ◽  
Polygonum Type ◽  
Wall Formation ◽  
Chalazal Megaspore

Cotula australis has a discoid heterogamous capitulum in which the outermost three whorls of florets are female and naked. The bisexual disk florets are fully fertile and have a four-lobed corolla with four shortly epipetalous stamens. The anthers contain only two microsporangia. Wall formation and microsporogenesis are described and the pollen grains are shed at the three-celled condition. The ovule is teguinucellate and the hypodermal archesporial cell develops directly as the megaspore mother cell. Megasporogenesis is normal and the monosporio embryo sac develops from the chalazal megaspore. Breakdown of the nucellar epidermis takes place when the embryo sac is binucleate and its subsequent development follows the Polygonum type. The synergids extend deeply into the micropyle and one persists until late in embryogeny as a haustorium. The development of the embryo is of the Asterad type, and the endosperm is cellular. C. coronopifolia agrees with C. australis in the presence of only two microsporangia in each anther and the development of a synergid haustorium.

Ultrastructural and cytological observations of apothecial tissues of Geopyxis carbonaria (Pezizales, Ascomycetes)

1990 ◽  
Vol 68 (2) ◽  
pp. 243-257 ◽  
Author(s):  
James W. Kimbrough ◽  
Jack L. Gibson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Mother Cell ◽  
Secondary Wall ◽  
Cell Stage ◽  
Wall Structures ◽  
Transmission Electron ◽  
Secondary Wall Formation ◽  
Characteristic Features

Cytological observations are made on apothecial tissues of Geopyxis carbonaria, using transmission electron microscopy. Characteristic features of both the medullary and ectal excipula are examined. Changes in ascus apex and wall structures are examined during ascus ontogeny, especially in relation to operculum position and structure. Ultrastructure of septum configuration is observed and compared in the excipulum, ascogenous hyphae, paraphyses, and at the base of young asci. Ascosporogenesis is observed from the ascus mother cell stage and initial spore delimitation until secondary wall formation. The cytological and ultrastructural observations on this species are discussed in relation to their possible taxonomic or phylogenetic value. Key words: ascosporogenesis, Discomycetes, ascospore ultrastructure, septal ultrastructure, cytochemistry.

scholarly journals Arabidopsis ICK/KRP cyclin-dependent kinase inhibitors function to ensure the formation of one megaspore mother cell and one functional megaspore per ovule

PLoS Genetics ◽  
2018 ◽  
Vol 14 (3) ◽  
pp. e1007230 ◽  
Author(s):  
Ling Cao ◽  
Sheng Wang ◽  
Prakash Venglat ◽  
Lihua Zhao ◽  
Yan Cheng ◽  
...  
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Kinase Inhibitors ◽  
Cyclin Dependent Kinase ◽  
Functional Megaspore

Female gametophyte and embryo development in western hemlock (Tsuga heterophylla)

1974 ◽  
Vol 52 (4) ◽  
pp. 885-893 ◽  
Author(s):  
Elizabeth A. Stanlake ◽  
John N. Owens
Keyword(s):  
Embryo Development ◽  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Morphological Study ◽  
Female Gametophyte ◽  
Tsuga Heterophylla ◽  
Western Hemlock ◽  
Seed Fall

A morphological study of the female gametophyte and embryo development was made for western hemlock (Tsuga heterophylla (Raf.) Sarg.) growing in the Victoria, B.C., area. Western hemlock follows a pattern of development similar to other members of the Pinaceae. A comparison was also made between development in western hemlock and other gymnosperm families. Meiosis of the megaspore mother cell in western hemlock begins in early February and is completed at the end of the first week in March. This is 3 weeks before pollination. Fertilization occurs 6 weeks after pollination, in the middle of May. Embryo development takes place throughout June and July and the embryo is mature by the middle of August. Seed fall occurs throughout September, 5 months after pollination.

Megagametogenesis, fertilization, and embryo development in Larixdecidua

1986 ◽  
Vol 16 (6) ◽  
pp. 1301-1309 ◽  
Author(s):  
Grzegorz Kosiński
Keyword(s):  
Cell Wall ◽  
Sexual Reproduction ◽  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Female Gametophyte ◽  
Nuclear Stage ◽  
Empty Seed ◽  
Development Failure ◽  
Major Factors ◽  
Female Gametophyte Development

The phenology of sexual reproduction in Larixdecidua Mill, varies from year to year, and some intra- and inter-clonal differences were also found. Megaspore mother cell meiosis occurred at the time of pollination, during the second half of April, resulting in three or four megaspores. The free nuclear stage and cell wall and archegonia formation were completed in late May and the first half of June. An average of four archegonia was observed in each ovule, but the number ranged from two to six. Fertilization occurred during the first 20 days of June, about 7 weeks after pollination. A four-tiered, 16-celled proembryo formed. Meristematic regions formed in the embryo from the end of June to mid-July. Fully developed embryos were observed in mid-August. Simple polyembryony and delayed cleavage polyembryony were observed. Lack of pollination, disturbances during megasporogenesis and female gametophyte development, failure of fertilization, and embryo degeneration are the major factors resulting in empty seed.

scholarly journals The TRAF Mediated Gametogenesis Progression (TRAMGaP) Gene Is Required for Megaspore Mother Cell Specification and Gametophyte Development

2017 ◽  
Vol 175 (3) ◽  
pp. 1220-1237 ◽  
Author(s):  
Sunil Kumar Singh ◽  
Vajinder Kumar ◽  
Ramamurthy Srinivasan ◽  
Paramvir Singh Ahuja ◽  
Shripad Ramchandra Bhat ◽  
...  
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Cell Specification ◽  
Gametophyte Development

ULTRASTRUCTURE OF THE DEVELOPING MEGASPORE MOTHER CELL OF GINKGO BILOBA

1967 ◽  
Vol 54 (3) ◽  
pp. 375-383 ◽  
Author(s):  
K. D. Stewart ◽  
E. M. Gifford
Keyword(s):  
Ginkgo Biloba ◽  
Mother Cell ◽  
Megaspore Mother Cell

scholarly journals The dyad gene is required for progression through female meiosis in Arabidopsis

Development ◽  
2000 ◽  
Vol 127 (1) ◽  
pp. 197-207 ◽  
Author(s):  
I. Siddiqi ◽  
G. Ganesh ◽  
U. Grossniklaus ◽  
V. Subbiah
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Female Gametophyte ◽  
Molecular Mechanisms ◽  
Higher Plants ◽  
Embryo Sac ◽  
Initial Step ◽  
Female Meiosis ◽  
Female Germ Cell ◽  
Further Development

In higher plants the gametophyte consists of a gamete in association with a small number of haploid cells, specialized for sexual reproduction. The female gametophyte or embryo sac, is contained within the ovule and develops from a single cell, the megaspore which is formed by meiosis of the megaspore mother cell. The dyad mutant of Arabidopsis, described herein, represents a novel class among female sterile mutants in plants. dyad ovules contain two large cells in place of an embryo sac. The two cells represent the products of a single division of the megaspore mother cell followed by an arrest in further development of the megaspore. We addressed the question of whether the division of the megaspore mother cell in the mutant was meiotic or mitotic by examining the expression of two markers that are normally expressed in the megaspore mother cell during meiosis. Our observations indicate that in dyad, the megaspore mother cell enters but fails to complete meiosis, arresting at the end of meiosis 1 in the majority of ovules. This was corroborated by a direct observation of chromosome segregation during division of the megaspore mother cell, showing that the division is a reductional and not an equational one. In a minority of dyad ovules, the megaspore mother cell does not divide. Pollen development and male fertility in the mutant is normal, as is the rest of the ovule that surrounds the female gametophyte. The embryo sac is also shown to have an influence on the nucellus in wild type. The dyad mutation therefore specifically affects a function that is required in the female germ cell precursor for meiosis. The identification and analysis of mutants specifically affecting female meiosis is an initial step in understanding the molecular mechanisms underlying early events in the pathway of female reproductive development.

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