Embryo sac development in soybean: cellularization and egg apparatus expansion

1990 ◽  
Vol 68 (10) ◽  
pp. 2135-2147 ◽  
Author(s):  
M. W. Folsom ◽  
D. D. Cass
Keyword(s):  
Ultrastructural Study ◽  
Cell Walls ◽  
Embryo Sac ◽  
Chain Structure ◽  
Mitotic Division ◽  
The Other ◽  
Synergid Cell ◽  
Egg Apparatus ◽  
Embryo Sac Development

An ultrastructural study of soybean embryo sac development was performed. Prior to the final mitotic division and cellularization a nuclear rearrangement occurs that involves the chalazal movement of one of the two micropylar nuclei. During cellularization this nucleus divides to form the egg and micropylar polar nuclei and produces the wall that separates the central ceil from title space occupied by the egg apparatus. Within this space the other nucleus divides to form the two synergid nuclei and one of the two walls that separate the egg and synergid cells from one another. Egg apparatus cells are initially densely cytoplasmic, each is enclosed by thick, highly dissected walls, and they are all similar with respect to distribution of organelles except that synergid nuclei are micropylar to the egg nucleus. There is a progressive thinning and segmentation of egg apparatus walls during cellular expansion until they resemble the beaded chain structure seen in the mature egg and synergid cell walls. Taken as a whole these observations suggest that the chalazal movement of one of the two micropylar nuclei during the 4-nucleate stage is pivotal in determining future patterns of egg apparatus development.

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.

scholarly journals Induction of Diploid Eggs With Colchicine During Embryo Sac Development in Populus

2010 ◽  
Vol 59 (1-6) ◽  
pp. 40-48 ◽  
Author(s):  
J. Wang ◽  
X. Y. Kang ◽  
D. L. Li ◽  
H. W. Chen ◽  
P. D. Zhang
Keyword(s):  
Generative Cell ◽  
Embryo Sac ◽  
Mitotic Division ◽  
Chromosome Counting ◽  
Paraffin Sections ◽  
Stigma Receptivity ◽  
The Third ◽  
Embryo Sac Development ◽  
2N Eggs ◽  
Colchicine Solution

Abstract Diploid (2n) eggs were induced by treating developing embryo sacs of Populus with colchicine solution, in order to produce triploid plants. The optimal pollinated time of female catkins was confirmed as timing point for each treatment. When female catkins of P. pseudo-simonii x P. nigra ‘Zheyin3#’ had become 5.62 ± 0.13 cm long 84 h after they emerged from their bract scales and all stigmas were exposed, pistils all over the entire catkin had optimal stigma receptivity. Observation of paraffin sections showed that embryo sac development of ‘Zheyin3#’, which initiated 12 h before pollination and finished 132 h after pollination, was a successive and asynchronous process. Generative cell division of pollen of the male parent P. x beijingensis took place 3-16 h after pollination. Catkins of 18-96 h after pollination of ‘Zheyin3#’ were treated with colchicine solution. In the progeny, twenty three triploids were detected by chromosome counting and the highest rate of triploids was 66.7% in one treatment. The rate of triploid yield was positively correlated with the frequency of four-nucleate embryo sacs (r = 0.6721, p = 0.0981) and was not significantly correlated with the percentages of uni-, twoand eight-nucleate embryo sac (r = -0.1667, p = 0.7210, r = -0.3069, p = 0.5031 and r = 0.0189, p = 0.9679, respectively), suggesting that the third mitotic division of embryo sac may be the effective stage to induce 2n eggs. Through this approach, completely homozygous 2n eggs can be produced. Its significance for plant breeding is discussed.

Analysis of Nondisjunction Induced by the R-X1 Deficiency during Microsporogenesis in Zea Mays L.

Genetics ◽  
1988 ◽  
Vol 119 (4) ◽  
pp. 975-980
Author(s):  
Z Y Zhao ◽  
D F Weber
Keyword(s):  
Zea Mays L ◽  
Embryo Sac ◽  
Mitotic Division ◽  
The Other ◽  
Chromosome 6 ◽  
Nucleolar Organizing Region ◽  
Sperm Nuclei ◽  
Embryo Sac Formation ◽  
And Control ◽  
Generative Nuclei

Abstract The r-X1 deficiency in maize induces nondisjunction at the second mitotic division during embryo sac formation. However, it was not known if this deficiency also induces nondisjunction during the microspore divisions. Microsporogenesis in plants lacking or containing this deficiency was compared using two approaches. First, chromosome numbers were determined in generative nuclei. Many (8.3%) of the generative nuclei in r-X1-containing plants were aneuploid; however, those from control plants were all haploid. Thus, this deficiency induces nondisjunction during the first microspore division. Second, nucleoli were analyzed in microspores. The only nucleolar organizing region in maize is on chromosome 6. If chromosome 6 underwent nondisjunction during the first microspore division, one nucleus in binucleate microspores would contain no nucleolus and the other would contain two nucleoli (or one nucleolus if the nucleoli fused). Only one (0.03%) microspore of this type was observed in control plants while 1.12% were found in r-X1-containing plants. Thus, the r-X1 deficiency induces nondisjunction of chromosome 6 during the first microspore division. However, both of the sperm nuclei in trinucleate microspores contained one nucleolus in r-X1-containing and control plants; thus, this deficiency does not induce nondisjunction of chromosome 6 (and presumably other chromosomes) during the second microspore division.

Cellularization of the female gametophyte in Ranunculus sceleratus

1989 ◽  
Vol 67 (5) ◽  
pp. 1325-1330 ◽  
Author(s):  
N. N. Bhandari ◽  
P. Chitralekha
Keyword(s):  
Female Gametophyte ◽  
Horizontal Cell ◽  
Embryo Sac ◽  
Cell Plate ◽  
Mitotic Division ◽  
The Other ◽  
Central Vacuole ◽  
Distinct Cell ◽  
Antipodal Cells ◽  
Vertical Cell

Wall formation in Ranunculus sceleratus takes place simultaneously at the micropylar and chalazal poles of the embryo sac. During the last (third) mitotic division resulting in an eight-nucleate embryo sac, three distinct cell plates are formed at either pole. Of the three cell plates, CPI (horizontal), CPE (oblique), and CPIII (vertical), the first two are formed between the separating chromatin masses of the two dividing nuclei. CPIII (vertical cell plate) arises subsequently between the first two plates. CPI (horizontal cell plate) extends perpendicular to the long axis of the embryo sac to separate the central vacuole and one nucleus (polar) from the quartet of nuclei. The other two cell plates extend simultaneously between the three remaining nuclei; CPII (oblique plate) cuts off one of the nuclei while CPIII (vertical cell plate) separates the other two. Consequently, the egg apparatus, central cell with two polar nuclei, and three antipodal cells are formed.

Early Development of the Macadamia Ovary

1981 ◽  
Vol 29 (2) ◽  
pp. 185 ◽  
Author(s):  
M Sedgley
Keyword(s):  
Light Microscopy ◽  
Early Development ◽  
Cell Walls ◽  
Cell Formation ◽  
Embryo Sac ◽  
The Other ◽  
Globular Embryo ◽  
Macadamia Integrifolia

Macadamia integrifolia ovaries were sampled for light microscopy from anthesis to 8 weeks after flowering. Both ovules increased in size following anthesis but only one was normally fertilized. Fertilization of one ovule appeared to inhibit fertilization of the other. The unfertilized ovule was eventually crushed by the fertilized ovule which developed a globular embryo with a short suspensor. Division of the endosperm preceded division of the embryo, and cell formation in the initially free nuclear endosperm progressed by the development of cell walls inwards from the embryo sac wall at the micropylar end of the embryo sac only. Thickenings developed on the walls of the embryo sac, persistent synergid and embryo and a hypostase developed at the base of the nucellus between the cavity occupied by the embryo sac and the integument. Both specializations are suggested to be important in the nutrition of the developing embryo. Ovaries which abscissed 4-5 weeks after anthesis had a similar anatomy to ovaries retained on the tree. Some embryos showed signs of degeneration but this was not considered to be the cause of abscission.

An ultrastructural study of vegetative incompatibility in plants

1978 ◽  
Vol 36 (2) ◽  
pp. 436-437
Author(s):  
Randy Moore
Keyword(s):  
Ultrastructural Study ◽  
Cell Walls ◽  
Growth And Development ◽  
Solanum Pennellii ◽  
Initial Product ◽  
Basic Aspect ◽  
Tissue Interactions ◽  
Graft Interface ◽  
Antigen Antibody ◽  
Standard Fixation

Cell and tissue interactions are a basic aspect of eukaryotic growth and development. While cell-to-cell interactions involving recognition and incompatibility have been studied extensively in animals, there is no known antigen-antibody reaction in plants and the recognition mechanisms operating in plant grafts have been virtually neglected.An ultrastructural study of the Sedum telephoides/Solanum pennellii graft was undertaken to define possible mechanisms of plant graft incompatibility. Grafts were surgically dissected from greenhouse grown plants at various times over 1-4 weeks and prepared for EM employing variations in the standard fixation and embedding procedure. Stock and scion adhere within 6 days after grafting. Following progressive cell senescence in both Sedum and Solanum, the graft interface appears as a band of 8-11 crushed cells after 2 weeks (Fig. 1, I). Trapped between the buckled cell walls are densely staining cytoplasmic remnants and residual starch grains, an initial product of wound reactions in plants.

Golgi Apparatus and Melanogenesis: Ultrastructural Study of a Human Cellular Blue Nevus (Melanocytoma)

1973 ◽  
Vol 31 ◽  
pp. 380-381
Author(s):  
S.R. Allegra
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Ultrastructural Study ◽  
The Other ◽  
Blue Nevus ◽  
Normal Complement ◽  
Golgi Vesicles ◽  
Golgi System ◽  
The Subject ◽  
Cellular Blue Nevus

The respective roles of the ribo somes, endoplasmic reticulum, Golgi apparatus and perhaps nucleus in the synthesis and maturation of melanosomes is still the subject of some controversy. While the early melanosomes (premelanosomes) have been frequently demonstrated to originate as Golgi vesicles, it is undeniable that these structures can be formed in cells in which Golgi system is not found. This report was prompted by the findings in an essentially amelanotic human cellular blue nevus (melanocytoma) of two distinct lines of melanocytes one of which was devoid of any trace of Golgi apparatus while the other had normal complement of this organelle.

An ultrastructural study on the shark liver

1990 ◽  
Vol 48 (3) ◽  
pp. 512-513
Author(s):  
Masako Yamada ◽  
Yutaka Tanuma
Keyword(s):  
Portal Vein ◽  
Kupffer Cells ◽  
Ultrastructural Study ◽  
Lipid Droplets ◽  
Microscopic Level ◽  
The Other ◽  
Fish Stock ◽  
Structural Studies ◽  
Light Microscopic Level ◽  
Perfusion Fixation

Although many fine structural studies on the vertebrate liver have been reported on mammals, avians, reptiles, amphibians, teleosts and cyclostomes, there are no studies on elasmobranchii liver except one by T. Ito etal. (1962) who studied it on light microscopic level. The purpose of the present study was to as certain the ultrastructural details and cytochemical characteristics of normal elasmobranchii liver and was to compare with the other higher vertebrate ones.Seventeen Scyliorhinus torazame, one kind of elasmobranchii, were obtained from the fish stock of the Ueno Zoo aquarium, Ueno, Tokyo. The sharks weighing about 300-600g were anesthetized with MS-222 (Sigma), and the livers were fixed by perfusion fixation via the portal vein according to the procedure of Y. Saito et al. (1980) for 10 min. Then the liver tissues were immersed in the same fixative for 2 hours and postfixed with 1% OsO4-solution in 0.1 Mc acodylate buffer for one hour. In order to make sure a phagocytic activity of Kupffer cells, latex particles (0.8 μm in diameter, 0.05mg/100 g b.w.) were injected through the portal vein for one min before fixation. For preservation of lipid droplets in the cytoplasm, a series of these procedure were performed under ice cold temperature until the end of dehydration.

Rapid Isolation of High Molecular Weight Urokinase from Native Human Urine

1982 ◽  
Vol 47 (03) ◽  
pp. 197-202 ◽  
Author(s):  
Kurt Huber ◽  
Johannes Kirchheimer ◽  
Bernd R Binder
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Urine ◽  
Gel Filtration ◽  
Chain Structure ◽  
The Other ◽  
Single Chain ◽  
Apparent Homogeneity ◽  
Sequential Adsorption

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.

Ultrastructural Observation on Embryo Sac Development inPhaius tankervilliae(Aiton)Bl.

2012 ◽  
Vol 30 (2) ◽  
pp. 188 ◽  
Author(s):  
Dong-Mei LI ◽  
Cheng-Hou WU ◽  
Xiu-Lin YE ◽  
Cheng-Ye LIANG
Keyword(s):  
Embryo Sac ◽  
Ultrastructural Observation ◽  
Embryo Sac Development
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