Development of the ovule and megagametophyte in Ecdeiocolea monostachya

1990 ◽  
Vol 3 (2) ◽  
pp. 265 ◽  
Author(s):  
P Rudall
Keyword(s):  
Pollen Morphology ◽  
Embryo Sac ◽  
Mature Embryo ◽  
Egg Apparatus ◽  
Australian Family ◽  
First Time ◽  
Western Australian

Ovule and megagametophyte development is described for the first time in Ecdeiocoleaceae, a small Western Australian family that has affinities with Restionaceae. The mature embryo sac has an egg apparatus, but other nuclei usually degenerate. The nucellus proliferates at the chalazal end of the embryo sac to forma prominent cup-shaped region that has no obvious homologue among related families in Poales, or tother monocotyledons. The data confirm evidence from anatomy and pollen morphology that Ecdeiocolea does not belong in Restionaceae, but do not indicate obvious relationships with other families.

Early embryogenesis in Arabidopsis thaliana. I. The mature embryo sac

1991 ◽  
Vol 69 (3) ◽  
pp. 447-460 ◽  
Author(s):  
S. G. Mansfield ◽  
L. G. Briarty ◽  
S. Erni
Keyword(s):  
Arabidopsis Thaliana ◽  
Endoplasmic Reticulum ◽  
Embryo Sac ◽  
Mature Embryo ◽  
Central Cell ◽  
Egg Cell ◽  
Cell Cytoplasm ◽  
Intimate Contact ◽  
Egg Apparatus ◽  
Common Wall

Arabidopsis thaliana has a seven-celled eight-nucleate megagametophyte of the Polygonum type; each cell type displays a different form of structural specialization. The egg apparatus cells are highly polarized; the egg has a large micropylar vacuole and chalazally sited nucleus, whereas the opposite is true for the synergids. At the chalazal region of the egg apparatus cells there are no cell wall boundaries, although their plasmalemmas are in intimate contact. The common wall between the two synergids is thin and irregular and contains plasmodesmatal connections. The synergid cytoplasm is rich in organelles; profiles of rough endoplasmic reticulum appear in masses of parallel stacked cisternae, and large accumulations of mitochondria occur adjacent to the filiform apparatus. The egg cell cytoplasm is quiescent; ribosome concentration and frequencies of dictyosomes and endoplasmic reticulum are noticeably lower and plastids are poorly differentiated. The central cell is long and vacuolate with a large diploid nucleus; fusion of the polar nuclei occurs prior to embryo sac maturity. The cytoplasm contains numerous starch-containing plastids accumulated in a shell around the nucleus. A high ribosome concentration and the absence of vacuoles and dictyosomes typifies the antipodal cell cytoplasm. All antipodal cells are interconnected by plasmodesmata as well as being connected to the nucellus and central cell. Key words: Arabidopsis, embryo sac, embryogenesis, cell specializations, stereology.

Ultrastructural observations of the mature megagametophyte and the fertilization in wheat (Triticum aestivum)

1985 ◽  
Vol 63 (2) ◽  
pp. 163-178 ◽  
Author(s):  
Ruilin You ◽  
William A. Jensen
Keyword(s):  
Triticum Aestivum ◽  
Pollen Tube ◽  
Cell Walls ◽  
Embryo Sac ◽  
Mature Embryo ◽  
Central Cell ◽  
The Other ◽  
Egg Cell ◽  
Filiform Apparatus ◽  
Egg Apparatus

The mature embryo sac of wheat contains an egg apparatus composed of an egg cell and two synergids at the micropylar end, a central cell with two large polar nuclei in the middle, and a mass of 20 to 30 antipodals at the chalazal end. A comparison was made of the ultrastructural features of the various cells of the embryo sac. The features included the position of the nucleus and vacuoles, the number, structure, and distribution of organelles, and the extent of the cell walls surrounding each cell. The pollen tube enters one synergid through the filiform apparatus from the micropyle. The penetration and discharge of the pollen tube causes the further degeneration of that synergid, which had already undergone changes before pollination. The second synergid does not change further in appearance following the penetration of the first by the pollen-altered tube. Half an hour after pollination at 20–25 °C, two male nuclei are seen in the cytoplasm of the egg and the central cell. At about 1 h after pollination, one sperm has made contact with the egg nucleus, while the other sperm is fusing with one of the polar nuclei.

Reproductive development in two species of Darwinia Rudge (Myrtaceae)

1969 ◽  
Vol 17 (2) ◽  
pp. 215 ◽  
Author(s):  
N Prakash
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Reproductive Development ◽  
Outer Zone ◽  
Mature Embryo ◽  
Globular Embryo ◽  
Primary Endosperm Nucleus ◽  
Oil Glands ◽  
Polygonum Type ◽  
History Of

In Darwinia the floral parts are differentiated in a "calyx-orolla-gynoeciumandroecium" sequence. In individual buds stages of microsporogenesis markedly precede corresponding stages of megasporogenesis. The anther is tetrasporangiate with all sporangia lying in one plane. The secretory tapetum is one- to three-layered within the same microsporangium and a large number of Ubisch bodies are formed. The anthers dehisce by minute lateral pores and an ingenious mechanism helps disperse the twocelled pollen grains. A basal placenta in the single loculus of the ovary bears four ovules in D. micropetala and two in D. fascicularis. In both species, however, only one ovule is functional after fertilization. The fully grown ovules are anatropous, crassinucellar, and bitegmic; the inner integument forms the micropyle. The parietal tissue is most massive at the completion of megasporogenesis but is progressively destroyed later. The embryo sac follows the Polygonum type of developnlent and when mature is five-nucleate, the three antipodals being ephemeral. Following fertilization, the primary endosperm nucleus divides before the zygote. Subsequent nuclear divisions in the endosperm mother cell are synchronous and lead to a free-nuclear endosperm which becomes secondarily cellular, starting from the micropylar end at the time the globular embryo assumes an elongated shape. Embryogeny is irregular and the mature embryo is straight with a massive radicle and a hypocotyl which terminates in two barely recognizable cotyledons. Sometimes the minute cotyledons are borne on a narrow neck-like extension of the hypocotyl. A suspensor is absent. Both integuments are represented in the seed coat and only the outer layer of the outer and the inner layer of the inner integuments, with their thick-walled tanniniferous cells, remain in the fully grown seed. The ovary wall is demarcated into an outer zone containing oil glands surrounded by cells containing a tannin-like substance and an inner zone of spongy parenchyma. In the fruit this spongy zone breaks down completely but the outer zone is retained. The two species of Darwinia, while closely resembling each other in their embryology, differ significantly from other Myrtaceae. However, no taxonomic conclusions are drawn at this stage, pending enquiry into the life history of other members of the tribe Chamaelaucieae.

scholarly journals Pollen morphology of Ukrainian species of the genus Pedicularis L. (Orobanchaceae Vent.)

2012 ◽  
Vol 24 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Olena M. Peregrym ◽  
Zoya M. Tsymbalyuk ◽  
Sergei L. Mosyakin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Taxonomic Revision ◽  
Palynological Data ◽  
First Time ◽  
Scanning Electron

Abstract Pollen grains of 10 species of Pedicularis occurring in Ukraine were investigated using light and scanning electron microscopy. Palynological data on 6 species are reported for the first time. General pollen morphology of the genus Pedicularis is presented. Three types of apertures (2-syncolpate, 3-colpate, and 3-syncolpate) and seven subtypes of sculpture (3-syncolpate pilate, 3-syncolpate microscabrate-tubeculate, 2-syncolpate microscabrate, 2-syncolpate microscabrate-tubeculate, 2-syncolpate microscabrate-tubeculate-perforate, 2-syncolpate microfoveolate, and 2-syncolpate microscabrate-perforate) are indentified. The subgenus Pedicularis is heterogeneous in its types of apertures and sculpture of the surface, which indicates the need of further taxonomic revision of the group.

scholarly journals Pollen morphology of the Balkan-Carpathian endemic Campanula lingulata Waldst. & Kit. (Campanulaceae)

2016 ◽  
pp. 75-82
Author(s):  
Marina Macukanovic-Jocic ◽  
Snezana Jaric
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Endemic Species ◽  
Pollen Morphology ◽  
Average Length ◽  
Pollen Grains ◽  
Polar Axis ◽  
First Time ◽  
Scanning Electron

Palynomorphological characteristics of Campanula lingulata, the Balkan-Carpathian endemic species growing in Serbia, have been investigated using light microscopy and scanning electron microscopy for the first time, in order to provide some information helpful for a better understanding of the taxonomic position of this species within the genus, as well as to contribute to the pollen atlas of Serbian apiflora. The pollen grains are radially symmetrical, isopolar, 3-zonoporate and medium-sized monads oblate-sphaeroidal in shape. Mean of the polar axis (P) is 27.6?1.9 ?m, while the average length of the equatorial axis (E) is 28.8?1.6 ?m. The apertures are operculate. The sculpturing pattern of the exine is microre?ticulate-microechinatae. The exine surface is covered with evenly distributed supratectal spinules of variable length and sparse granules. The longest supratectal spinules are 0.64?0.05 ?m in length and the smallest sculptural elements are less than 0.2 ?m high. The microechinae density per sample area of 5 ?m x 5 ?m averages 17.4?2.4.

Symplastic communication between the central cell and the egg apparatus cells in the embryo sac of Torenia fournieri Lind. before and during fertilization

Planta ◽  
2000 ◽  
Vol 211 (1) ◽  
pp. 158-162 ◽  
Author(s):  
Yu-Zhen Han ◽  
Bing-Quan Huang ◽  
Sze-Yong Zee ◽  
Ming Yuan
Keyword(s):  
Embryo Sac ◽  
Central Cell ◽  
Torenia Fournieri ◽  
Egg Apparatus

Australian pirates: systematics and phylogeny of the Australasian pirate spiders (Araneae:Mimetidae), with a description of the Western Australian fauna

2009 ◽  
Vol 23 (3) ◽  
pp. 231 ◽  
Author(s):  
Danilo Harms ◽  
Mark S. Harvey
Keyword(s):  
New Species ◽  
New Zealand ◽  
Morphological Character ◽  
Systematic Position ◽  
Taxonomic Changes ◽  
Species Groups ◽  
First Time ◽  
Expanded Concept ◽  
Western Australian ◽  
The Web

Pirate spiders (Mimetidae) are well known for their specialised feeding ecology. They are vagrant araneophagic predators, enter the webs of their prey spiders and exhibit patterns of aggressive mimicry to overcome the web owner. The mimetid fauna of Australia and New Zealand currently consists of 26 species in the following three genera: Australomimetus Heimer, 1986 (18 species), Mimetus Hentz, 1832 (six species), and Ero C.L. Koch, 1836 (two species). The systematic position of the majority of Australasian mimetids was investigated through phylogenetic techniques utilising morphological character systems of 29 exemplar taxa and 87 characters, including the first examination of spinneret structure in species of Australomimetus. The results support an expanded concept for Australomimetus, which, apart from the introduced Ero aphana (Walckenaer, 1802), is found to contain the entire Australian and New Zealand mimetid fauna, also recorded from Asia. The following taxonomic changes are proposed: A. catulli (Heimer, 1989), comb. nov., A. hannemanni (Heimer, 1989), comb. nov., A. japonicus (Uyemura, 1938), comb. nov., A. mendicus (O. P. Cambridge, 1879), comb. nov. and A. sennio (Urquhart, 1891), comb. nov.; Ero luzoniensis Barrion & Litsinger, 1995 is synonymised with Ero aphana, and A. andreae Heimer, 1989 is synonymised with A. daviesianus Heimer, 1986; Mimetus tikaderi Gajbe, 1992 from India is excluded from Mimetidae, and referred to Liocranidae. The Western Australian mimetid fauna is described for the first time and comprises nine species of Australomimetus, including the following five new species: A. diabolicus, sp. nov., A. djuka, sp. nov., A. dunlopi, sp. nov., A. nasoi, sp. nov. and A. stephanieae, sp. nov. Several species-groups of Australomimetus are identified.

scholarly journals Assessment of Cognition and Personality as Potential Endophenotypes in the Western Australian Family Study of Schizophrenia

2017 ◽  
Vol 44 (4) ◽  
pp. 908-921 ◽  
Author(s):  
Nina S McCarthy ◽  
Johanna C Badcock ◽  
Melanie L Clark ◽  
Emma E M Knowles ◽  
Gemma Cadby ◽  
...  
Keyword(s):  
Family Study ◽  
Australian Family ◽  
Western Australian

scholarly journals New data on Salix anatolica (Salicaceae) endemic to Turkey

Phytotaxa ◽  
2014 ◽  
Vol 167 (1) ◽  
pp. 111 ◽  
Author(s):  
SALİH TERZİOĞLU ◽  
BEDRİ SERDAR ◽  
MUSTAFA KARAKÖSE ◽  
KAMİL COŞKUNÇELEBİ ◽  
MUTLU GÜLTEPE
Keyword(s):  
Pollen Morphology ◽  
Conservation Status ◽  
Female Flower ◽  
Male And Female ◽  
Anatomical Features ◽  
First Time

The endemic Anatolian willow, Salix anatolica (Salicaceae), was described based on solely female individuals in 2008. It was re-collected and the description was emended based on both male and female flower properties in the present study. Additionally, the pollen morphology, wood anatomical features and conservation status of S. anatolica are presented for the first time.

Ultrastructural Aspects of the Mature Embryo Sac of Soybean, Glycine max (L.) Merr.

1984 ◽  
Vol 145 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Michael W. Folsom ◽  
Curt M. Peterson
Keyword(s):  
Glycine Max ◽  
Embryo Sac ◽  
Mature Embryo ◽  
Glycine Max L
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