scholarly journals A Contribution to the Embryology of Rhynchelytrum repens (Willd) C.E. Hubbard

1970 ◽  
Vol 7 (7) ◽  
pp. 37-40 ◽  
Author(s):  
Mohammed Inamuddin ◽  
Beatrice Were ◽  
Mohammad Saquib
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Pollen Grains ◽  
Middle Layer ◽  
Microspore Mother Cell ◽  
Polygonum Type ◽  
Dense Cytoplasm ◽  
Scientific World ◽  
Tapetal Cells ◽  
Functional Megaspore

The present investigation deals with morphological and embryological studies of Rhynchelytrum repens (Willd) C.E. Hubbard. The development of anther walls are found to be Monocotyledonous type. The tapetal cells are substantially large, glandular and uninucleate. The middle layer is ephemeral and their cells are small in size. It is sandwiched between endothecial and tapetal layer. The endothecial cells are large and develop fibrous thickenings. The microspore mother cell undergoes two successive reduction divisions, giving rise to isobilateral microspore tetrad. The tetrad separates and give rise to four pollen grains. Occasionally, the anther show degenerating pollen grains before dehiscence. Formation of Ubisch's bodies has also been observed. The pollen grains shed at three celled stage. The exine is thick while intine is thin. The ovule is anatropous, bitegmic and crassinucellate. The female archesporial cell becomes large with dense cytoplasm. It directly functions as megaspore mother cell and undergoes two meiotic divisions to produce a linear megaspore tetrad. The micropylar three cells degenerate and chalazal one becomes functional. The chalazal functional megaspore undergoes three mitotic divisions without wall formation and produces 8-nucleate embryosac. Such 8-nucleate embryosac organizes into Polygonum type of embryosac. It is interesting to note that some somatic cells of the ovule undergo nuclear divisions and give rise to facultative apomictic embryosacs. Key Words: Eldoret; Microsporangium; Ubisch's bodies; Facultative apomixis; Female gametophyte. DOI: 10.3126/sw.v7i7.3822 Scientific World Vol.7(7) 2009 pp.37-40

Sporogenesis, Gametogenesis, and embryogeny of Wahlenbergia bicolor N. Lothian

1963 ◽  
Vol 11 (2) ◽  
pp. 152 ◽  
Author(s):  
G Want
Keyword(s):  
Mother Cell ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Type A ◽  
Middle Layer ◽  
Anther Wall ◽  
Suspected Case ◽  
Polygonum Type ◽  
Chalazal Megaspore ◽  
Coastal Species

In Wahlenbergia bicolor, the anther wall is composed of four layers: epidermis, endothecium, middle layer, and tapetum. Wall formation and microsporogenesis are described, and the pollen grains are shed at the two-celled condition. The ovules are tenuinucellate, with a hypodermal archesporial cell which develops directly as the megaspore mother cell. Megasporogenesis is normal, and a monosporic eight-nucleate embryo sac of the most common Polygonum type develops from the chalazal megaspore. The antipodals degenerate before fertilization. The development of the embryo is of the solanad type. A suspected case of polyembryony was observed. The endosperm is cellular from its inception, and so conforms to the Codonopsis type. A micropylar and a chalazal haustoriurn, both consisting of two uninucleate cells, are formed from the endosperm. Comparative studies were made with a known but as yet undescribed coastal species of Wahlenbergia, and no differences were found.

Comparative study of gametophyte development in the some species of the genus Onobrychis: Systematic significance of gametophyte futures

Biologia ◽  
2011 ◽  
Vol 66 (2) ◽  
Author(s):  
Abdilkarim Chehregani ◽  
Fariba Mohsenzadeh ◽  
Nayereh Tanaomi
Keyword(s):  
Light Microscopy ◽  
Female Gametophyte ◽  
Male Gametophyte ◽  
Outer Integument ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Polygonum Type ◽  
Male And Female ◽  
Number Of Layers ◽  
Functional Megaspore

AbstractMale and female gametophytes have special characters that show a great variety in different taxa. In this study, gametophytes of four species belonging to three sections of the genus Onobrychis Mill. were studied with light microscopy. Results showed that the ovular primordium is tetra-zonate and gives rise to an anatropous ovule. The archesporium may consist of one or more archeosporial cells, but only one of them undergoes meiosis, forming a linear or T-shaped tetrad. Normally, only a single megaspore is functional which is located in the chalazal position while the others degenerate very soon. The young ovule is hemi-anatropous but the mature is anatropous, crassinucellar and bitegmic; integuments form a zig-zag micropyle. A 7-celled embryo-sac is formed corresponding to the Polygonum type. Based on our results, the ovular variable characters are the form and condition of ovary, presence or absence of ovary peduncle, the number and condition of ovule in ovary, length and width of ovule, length and width of embryo sac, number of layers in outer integument, condition of megaspore, alignment pattern of the integuments, asymmetrical initiation of the outer integument, shape of tetrad with the presence of one functional megaspore and so on. The separator characters in male gametophyte are including tri-cellular pollen grains and the number of tapetum nuclei. According to our study the female gametophyte characters are more variable than male gametophyte. The present study provides the first report on embryological description in the genus Onobrychis and also in section Heliobrychis.

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.

scholarly journals Dynamics of Polysaccharides and Neutral Lipids during Anther Development in Castor (Ricinus communis)

2015 ◽  
Vol 140 (4) ◽  
pp. 356-361 ◽  
Author(s):  
Dongmei Wei ◽  
Huimin Xu ◽  
Ruili Li
Keyword(s):  
Neutral Lipids ◽  
Ricinus Communis ◽  
Starch Content ◽  
Single Layer ◽  
Pollen Grains ◽  
Middle Layer ◽  
Anther Development ◽  
Anther Wall ◽  
Starch Grains ◽  
Tapetal Cells

Anthers contain starch and neutral lipids, which have key roles in microspore ontogeny and gametophyte development. In this study, we observed the dynamic changes in starch and neutral lipids in the anther developmental processes of castor (Ricinus communis) by cytochemical methods. Starch grains and neutral lipids presented a regular dynamic distribution during anther development. In young anthers, some neutral lipids accumulated in sporogenous cells, whereas neutral lipids disappeared with microspore growth. At the late microspore stage, starch grains began to accumulate in microspores, and the starch content of bicellular pollen significantly increased after microspore mitosis. At anthesis, starch grains and neutral lipids accumulated in the mature pollen grains. Visible changes occurred in anther wall cells. The epidermis, middle layer, and tapetum were degenerated, and only a single layer of endothecium remained at anthesis. The dynamic variation of starch grains and neutral lipids in tapetal cells was consistent with the changes in microspores and pollen during anther development. All these findings demonstrated that tapetal cells directly interacted with the developing gametophytes. The tapetal cells play an important role in supplying nutritional substances for microspore absorption. Moreover, the endothecium protects the pollen and contributes to anther dehiscence. The results of this study provide a foundation for the further research on sexual reproduction in angiosperms.

Anther and Ovule Development in Tasmannia (Winteraceae)

1992 ◽  
Vol 40 (6) ◽  
pp. 877 ◽  
Author(s):  
N Prakash ◽  
AL Lim ◽  
FB Sampson
Keyword(s):  
Mother Cell ◽  
Female Gametophyte ◽  
Cell Plate ◽  
Basic Type ◽  
Ovule Development ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Secretory Type ◽  
Mother Cells ◽  
Female Gametophyte Development

Three species of Tasmannia R.Br. ex DC., T. glaucifolia, T. insipida and T. stipitata are studied. The anther is tetrasporangiate and its waU development conforms to the Basic type. The tapetum follows the secretory type of development. Cytokinesis in the microspore mother cells is simultaneous but an evanescent cell plate is present at telophase I and anaphase I1 during meiosis. Pollen tetrads are permanent and tetrahedral. The mature pollen is anaulcerate, reticulate and 2-celled. The ovule. is anatropous, bitegmic and crassinucellate. The micropyle in T. stipitata and T. Glaucifolia is formed by the inner integument only whereas in T. insipida it is formed by both the integuments and is zigzag in outline. Meiosis in the single megaspore mother cell produces a linear or T-shaped megaspore tetrad in T. stipitata and T. glaucifolia but only a linear tetrad in T. insipida. Female gametophyte development is of the monosporic Polygonum type. Fertilisation is porogamous; triple fusion and syngamy occur simultaneously.

Floral morphology and embryology of two Australian species of Citrus (Rutaceae)

2001 ◽  
Vol 49 (2) ◽  
pp. 199 ◽  
Author(s):  
Kerri Clarke ◽  
Nallamilli Prakash
Keyword(s):  
Female Gametophyte ◽  
Floral Morphology ◽  
Anther Wall ◽  
Microspore Development ◽  
Common Occurrence ◽  
Citrus Species ◽  
Polygonum Type ◽  
Australian Species ◽  
Tapetal Cells ◽  
Antipodal Cells

The floral morphology and embryology of two species of Australian Citrus L. occurring in the most southerly range of the genus, C. australasica F.Muell. and C. australis (Mudie) Planchon, have been studied. Cytokinesis in the microsporocytes was simultaneous resulting in tetrahedral tetrads. Tapetal cells were bi- to multinucleate and unevenly one- or two-layered. Microspore development was frequently asynchronous. Anther wall consisted of a layer of endothecium, three to five middle layers and one or two layers of Secretory tapetum. The ovules were anatropous, bitegmic and crassinucellate. Although multiple sporogenous cells that grew into multiple megasporocytes were common, occurrence of twin or multiple gametophytes was rare. Development of the female gametophyte was of the Polygonum type, with antipodal cells frequently persisting until after fertilisation. Endosperm was of the Nuclear type while embryogeny was of the Onagrad type. Both integuments contributed to the seed coat. Cells of the outer layer of the testa developed fibrous thickenings and secreted mucilage. Seeds were monoembryonate and seed germination was hypogeal. The recent move incorporating Australian native citrus species in to the genus Citrus was supported on the grounds of close embryological similarities.

Embryology and Reproductive Ecology of the Darling Lily, Crinum flaccidum Herbert

1990 ◽  
Vol 38 (5) ◽  
pp. 433 ◽  
Author(s):  
G Howell ◽  
N Prakash
Keyword(s):  
Pollen Grains ◽  
Mature Embryo ◽  
Microspore Mother Cell ◽  
Polygonum Type ◽  
Binucleate Cells ◽  
Cell Layers ◽  
Nectar Sugar ◽  
Endosperm Formation ◽  
Successive Cytokinesis ◽  
Seed Coats

In Crinum flaccidum the anthers are versatile and tetrasporangiate with a secretory tapetum of binucleate cells. Successive cytokinesis in microspore mother cell results in isobilateral and decussate microspore tetrads. The mature pollen grains are single, spheroidal, disulculate, echinate and 2-celled. In the mature anthers, fibrous thickenings develop not only in the endothecium but also in two or three middle cell layers and the connective tissue before latrorse dehiscence. A lobed tissue in each of the three locules of the ovary serves ovular and placental functions. Each extension of the 5-7 paired lobes represents an ategmic ovule. The development of the female gametophyte conforms to the Polygonum type. Usually only one gametophyte is present in each lobe but occasionally several may occur. Bulb growth is monopodial with normally three umbels produced per plant, each carrying an average of 10 flowers, only two or three of which are open at any one time. Nectar sugar concentration was measured at 14.2% (w/w), of which 44.8% of solids was sucrose and 3.9% either glucose or fructose. The protandrous flowers are phalenophilous, pollinated by sphingid moths. The endosperm formation is of the nuclear type. In the absence of seed coats and the nucellus at maturity, the outer layers of the endosperm become corky following the activity of a phellogen. Embryogeny appears to be of the Asterad type. The mature embryo is straight and chlorophyllous. The large (5.3 g) seeds are 89% water and show no dormancy, germinating without an external supply of water, sometimes while still on the parent plant.

Sexual reproduction in subalpine fir (Abies lasiocarpa)

1981 ◽  
Vol 59 (12) ◽  
pp. 2650-2666 ◽  
Author(s):  
Hardev Singh ◽  
John N. Owens
Keyword(s):  
Female Gametophyte ◽  
Pollen Grains ◽  
Reproductive Phenology ◽  
Abies Lasiocarpa ◽  
Subalpine Fir ◽  
Young Embryo ◽  
Tapetal Cells ◽  
Well Differentiated ◽  
Mother Cells ◽  
Embryonal Mass

Reproductive phenology and anatomy of postdormancy phases of a population of Abies lasiocarpa (Hook.) Nutt. (subalpine fir) from a natural stand near Prince George, B.C., have been studied. The plants exhibited a 1-year type of reproductive cycle. By the end of March, the pollen cones had broken dormancy and contained pollen mother cells (PMC) in premeiotic stages. The PMCs entered meiosis in the 1st week of April and formed tetrads in the 3rd week. The tapetal cells, meanwhile, became binucleate, and then several went through endomitoses. The tapetal cell walls dissolved as the microspores separated from the tetrads. Orbicules were present around the degenerating cytoplasms of tapetal cells. Pollen grains were shed at the five-celled stage in the 3rd week of May.By the end of March, the ovulate cones had also broken dormancy and the ovules contained one to three hypodermal archesporial cells. Initiation of the integument and the formation of megaspore triads were observed in the 3rd week of April. By the 3rd week of May, at the time of pollination, the integument had developed a stigmatic micropylar funnel which received the pollen grains. During the postpollination stages the flange of the funnel became folded, and the nucellus grew up closer to the pollen grains. The nucellar cells at its tip degenerated to form a pollen chamber which contained the pollen grains. Pollen germination, pollen tube growth through the nucellus, and syngamy took only 4–6 days, and occurred at the end of June.The female gametophyte was rather long and narrow and bore two to three archegonia. The proembryo comprised four tiers of four cells each. The first set of suspensors developed from the subterminal tier of cells. The four terminal cells formed the embryonal mass but they contributed unequally. The proximal cells of the embryonal mass formed a massive secondary suspensor. Differentiation of root initials and the initiation of cotyledons in the young embryo took place in the 4th week of July, and the seeds matured in the 3rd week of August. The mature seed comprised a long and well-differentiated embryo, the female gametophyte, most of whose cells were gorged with protein bodies and lipid droplets, and a thick seed coat which was internally differentiated into three tissue layers. The outermost layer of gametophytic cells was devoid of any storage products.

Embryology of Polygonatum (Asparagaceae) and its systematic significance

Phytotaxa ◽  
2018 ◽  
Vol 350 (3) ◽  
pp. 235
Author(s):  
YUAN-YUAN SONG ◽  
YUN-YUN ZHAO ◽  
JIA-XI LIU
Keyword(s):  
Female Gametophyte ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Mature Pollen ◽  
Polygonum Type ◽  
Male And Female ◽  
Systematic Significance ◽  
Embryo Sac Development

In this study, we systematically studied the microsporogenesis, megasporogenesis, as well as development of male and female gametophyte of Polygonatum macropodum and P. sibiricum using the conventional paraffin sectioning technique. Our results showed that 1) microsporocytes cytokinesis is of the successive type; 2) microspore tetrads are tetragonal or tetrahedral; 3) mature pollen grains are two-celled or three-celled; 4) ovary is superior and trilocular, with axile placentas bearing 4–6 anatropous per locule; 5) ovules are anatropous, crassinucellate and bitegmic, with micropyle formed by the inner integument; 6) megaspore tetrads are linear or T-shaped; 7) embryo sac development is typically of Polygonum-type. The embryological features of Polygonatum support its inclusion of Asparagaceae in Asparagales.

scholarly journals Cytochemical and ultrastructural observations of anthers and pollen grains in Lathyrus undulatus Boiss

2011 ◽  
Vol 70 (1) ◽  
pp. 53-64 ◽  
Author(s):  
Filiz Vardar ◽  
Meral Ünal
Keyword(s):  
Morphological Characteristics ◽  
Pollen Grains ◽  
Middle Layer ◽  
Mature Pollen ◽  
Anther Wall ◽  
Tapetal Cells ◽  
Microspore Stage ◽  
Pollen Stage ◽  
Mature Anther ◽  
Insoluble Polysaccharides

Cytochemical and ultrastructural observations of anthers and pollen grains inLathyrus undulatusBoissInLathyrus undulatusBoiss. (Fabaceae), the young microspore stage of anther development was characterized by the enlarged secretory tapetal cells, which presented an intense reaction with regard to protein, insoluble polysaccharides and lipids. At bicellular pollen stage, the middle layer and the tapetum degenerated. After degradation of the tapetum, epidermis and single row U-shaped endothecium existed in the mature anther wall, and pollen grains remained in the locus. Young microspores had a spherical and centrally located nucleus with one or two nucleoli, many spherical lipid bodies and starchy plastids. A mature pollen grain contains insoluble polysaccharides, proteins, lipids and calcium. The mature pollen had the following morphological characteristics: 3-zonocolporate, prolate, tectate (imperforate) type of exine and perforate type of structure. The intine formed an important constituent portion of the wall, and consisted two sublayers: an outer intine (exintine) and an inner intine (endintine). The well-defined exine was made up of lipoidal substances and protein, but the intine composed of insoluble polysaccharides and protein. The bicellular state of the pollen grains persisted to anthesis.

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