Hypostase development in Ornithogalum caudatum (Liliaceae) and notes on other types of modifications in the chalaza of angiosperm ovules

1980 ◽  
Vol 58 (19) ◽  
pp. 2059-2066 ◽  
Author(s):  
Varien R. Tilton
Keyword(s):  
Embryo Sac ◽  
Mitotic Division ◽  
Integral Function ◽  
Developmental Changes ◽  
Storage Tissue ◽  
Storage Product ◽  
The Third ◽  
Carbohydrate Storage ◽  
Mature Ovule ◽  
Ornithogalum Caudatum

Seven types of chalazal modifications have been reported to occur as normal developmental changes in angiosperm ovules. Among them is the hypostase, a group of usually lignified cells. In Ornithogalum, hypostase differentiation becomes evident during the meiotic–mitotic interphase. Differentiation proceeds toward the micropylar end of the ovule at first but later becomes bidirectional. Differentiation is usually completed after the third mitotic division of the megagametophyte has occurred. One to three hypostase cells per ovule have what appears to be a nonstarch carbohydrate storage product. The greatest proportion of starch reserves in the mature ovule occurs in the chalazal end of the nucellus and, although the hypostase does not seem to be an important storage tissue, it probably has an integral function in the translocation of nutrients into the megagametophyte and, after fertilization, into the embryo sac.

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.

Detection of the time of occurrence of nondisjunction induced by the r-X1 deficiency in Zea mays L.

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 782-785 ◽  
Author(s):  
Kevin D. Simcox ◽  
Jeffery D. Shadley ◽  
David F. Weber
Keyword(s):  
Zea Mays ◽  
Key Words ◽  
Zea Mays L ◽  
Embryo Sac ◽  
Mitotic Division ◽  
Polar Nucleus ◽  
Chromosome 6 ◽  
High Frequencies ◽  
The Third ◽  
Β Carotene

The r-X1 deficiency in maize produces high frequencies of aneuploid progeny by inducing nondisjunction during embryo sac development. The purpose of this investigation was to determine the embryo sac division at which the nondisjunctive event takes place. Monosomic-6 individuals were generated by crossing r-X1 containing plants by those carrying the y-pastel-8549 allele of the Y locus on chromosome 6. A strict dosage relationship exists between the number of dominant alleles of the Y locus and the level of β-carotene in the endosperm. We found that the level of β-carotene in the endosperm of kernels containing monosomic-6 embryos was comparable with that found in endosperms with one Y allele. This indicated that they contained only one maternally contributed chromosome 6. Only nondisjunction at the second postmeiotic division could have produced such an endosperm; thus, the nondisjunctive event occurs at this division. Another endosperm type expected from nondisjunction at this same division, with three dominant Y alleles, was not found. The absence of this endosperm type suggests that the egg nucleus and the polar nucleus originating at the micropylar pole are sister nuclei that arose from the same cell at the third embryo sac mitotic division. Key words: aneuploidy, embryo sac, nondisjunction, r-X1 deficiency, Zea.

Growth and moulting in nematodes: moulting and development of the hatched larva of Rotylenchulus reniformis

Parasitology ◽  
1984 ◽  
Vol 89 (1) ◽  
pp. 107-120 ◽  
Author(s):  
A. F. Bird
Keyword(s):  
Developmental Changes ◽  
Adult Males ◽  
Rotylenchulus Reniformis ◽  
Head Region ◽  
Immature Female ◽  
The Third ◽  
Final Moult ◽  
Developmental Sequences ◽  
Transmission Electron ◽  
Moist Environment

SummaryThe morphology of the post-hatch moulting and developmental sequence of an amphimictic population of Rotylenchulus reniformis has been examined in living and fixed material. Under suitable conditions of temperature and in a moist environment the 2nd-stage larva (L2) undergoes a series of 3 moults and developmental changes which result in the formation of males and immature females. After hatching and prior to the start of the first of these moults (the second moult), there is a pre-moult period, usually of 3–5 days duration. The morphology of the entire moulting and developmental sequences, from L2 to just after the final moult, has been followed in single living specimens of a parasitic nematode using differential interference contrast optics, and sections cut through different stages have been observed under the transmission electron microscope. These moulting sequences (at 24 °C) take place at similar times in developing males and females. The second moult takes place on the second day after commencement of moulting, the third on the third or fourth days and the fourth and final moult on the sixth or seventh days, followed by further development over several days to give rise to the adult male and the immature female. The ultrastructure associated with some of the more obvious of these developmental changes is described and includes the morphology of the head region and cuticles of L2, L4, adult males and immature females, the oesophageal glands of the immature female and the copulatory spicules and spermatozoa of the male.

scholarly journals On the Embryology of Two Species of Genus Lepidium (Brassicaceae)

HortScience ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 582-588
Author(s):  
Elina Yankova-Tsvetkova ◽  
Ivanka B. Semerdjieva ◽  
Rozalia Nikolova ◽  
Valtcho D. Zheljazkov
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Middle Layer ◽  
Reproductive Capacity ◽  
Marginal Lands ◽  
Potential Development ◽  
The Family ◽  
Mature Ovule ◽  
The Stability ◽  
Cultivation Techniques

Some species of genus Lepidium of the family Brassicaceae are ruderal plants, and they can grow well on less fertile soils and may have potential as oilseed crops for marginal lands. To develop cultivation techniques for wild species, the reproductive capacity of the species needs to be revealed. The objective of this work was embryological study of two Lepidium species (L. campestre and L. ruderale). As a result of the study, the main features of male and female generative spheres were established. Male generative sphere: The anther is tetrasporangiate and its wall, the development of which follows the monocotyledonous-type, consists of epidermis, endothecium, one middle layer, and glandular tapetum. Predominantly, tetrahedral microspore tetrads form after simultaneous type of microsporogenesis. The mature pollen grains are two-celled. Female generative sphere: The mature ovule is ana-amphytropous, crassinucellate, and bitegmic with unicellular archesporium that functions as a megaspore mother cell without cutting off of parietal cells. The development of the embryo sac follows the polygonum-type development. The embryo and endosperm develop after the onagrad-type embryogenesis. The established peculiarities of the reproductive biology characterize the studied species as sexually reproducing taxa that guarantee the stability of size of their populations. This is important for the conservation of these species as part of the Bulgarian flora biodiversity given their status of valuable medicinal plants. The data obtained will contribute to the knowledge of the embryological characteristic of genus Lepidium. The results contribute to the understanding of Lepidium biology and potential development of Lepidium species as oilseed cash crops for marginal lands.

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.

Embryological studies in Taraxacum udum Jordan (sect. Palustria)

Botany ◽  
2013 ◽  
Vol 91 (9) ◽  
pp. 614-620 ◽  
Author(s):  
Krystyna Musiał ◽  
Patrycja Górka ◽  
Maria Kościńska-Pająk ◽  
Paweł Marciniuk
Keyword(s):  
Rare Species ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Type Ii ◽  
Additional Source ◽  
Storage Tissue ◽  
Mode Of Reproduction ◽  
Autonomous Endosperm ◽  
Endosperm Formation ◽  
Single Locality

The present paper reports our observations on the mode of reproduction in Taraxacum udum (sect. Palustria), a very rare species in Poland, known only from a single locality. Based on the analysis of the developmental processes in the ovules, it can be concluded that this bog dandelion is an obligate and autonomous apomict. Its reproduction involves (i) restitutional diplospory, also known as Taraxacum type; (ii) parthenogenesis; and (iii) autonomous endosperm formation. Moreover, observations on the anatomy of ovules confirmed the occurrence of a special storage tissue around the embryo sac, which is considered to be an additional source of nutrition for the embryo. An examination of the anthers showed that, in spite of highly disturbed meiosis, apomictic T. udum produces pollen but pollen grains are heterogeneous in size and stainable using an acetocarmine test.

Series summable as Arithmetical Progressions

1925 ◽  
Vol 23 ◽  
pp. 14-15
Author(s):  
A. A. Krishnaswami Ayyangar
Keyword(s):  
Integral Function ◽  
The Third ◽  
Image Position ◽  
Rational Integral

We may group the terms of the A. P. a, a + d, a + 2d, …… as follows: the first p terms, the next p + t terms, the next p + 2t terms, and so on. The sum of the terms comprising the nth group iswhich is a rational integral function of n of the third degree.

scholarly journals The formation of integuments, megasporogenesis and megagametogenesis in Dendrobium catenatum, with special discussions on embryo sac types and section techniques

2021 ◽  
Vol 45 (2) ◽  
pp. 177-184
Author(s):  
Yong Chen ◽  
Xiaofeng Wang ◽  
Liang Li ◽  
Chengqi Ao
Keyword(s):  
Meiotic Division ◽  
Embryo Sac ◽  
Mitotic Cell ◽  
Mature Embryo ◽  
Archesporial Cell ◽  
Nucellar Cell ◽  
Polygonum Type ◽  
Cell Divisions ◽  
Mature Ovule ◽  
Branching System

The formation of integuments, megasporogenesis and megagametogenesis in Dendrobium catenatum, an economically important orchid, are observed. After pollination, mitotic cell divisions of the placental epidermis result in the formation of a branching system of outgrowths. The tip of each branch consists of an archesporial cell derived from the differentiation of the terminal subepidermal nucellar cell. It differentiates directly into a megasporocyte. The first division of the meiosis of the megasporocyte produces a dyad approximately equal in size, in which the micropylar cell promptly degenerates. The second meiotic division of the remaining dyad cell results in the formation of two megaspores of unequal size. The larger chalazal cell becomes functional and eventually develops into a mature megagametophyte. The development of the megagametophyte conforms to the Monosporic Polygonum type. The final arrangement of the mature embryo sac conforms to a sevencelled/ eight-nucleate structure. The mature ovule is bitegmic, tenuinucellate and has an anatropous orientation. In the present study, we also discuss the differences between three main types of embryo sac development and the improvement of section techniques.

scholarly journals II. On the attractions of an extensive class of spheroids

1812 ◽  
Vol 102 ◽  
pp. 46-82 ◽  
Keyword(s):  
Integral Function ◽  
Attractive Force ◽  
General Description ◽  
Separate Paper ◽  
The Third ◽  
Algebraic Expressions ◽  
The Earth ◽  
Extensive Class ◽  
The Subject ◽  
Ingenious Method

In this discourse I propose to investigate the attractions of a very extensive class of spheroids, of which the general description is, that they have their radii expressed by rational and integral functions of three rectangular co-ordinates of a point in the surface of a sphere. Such spheroids may be characterized more precisely in the following manner: conceive a sphere of which the radius is unit, and three planes intersecting one another at right angles in the centre; from any point in the surface of the sphere draw three perpendicular co-ordinates to the fixed planes, and through the same point in the surface likewise draw a right line from the centre, and cut off from that line a part equal to any rational and integral function of the three co-ordinates: then will the extremity of the part so cut off be a point in the surface of a spheroid of the kind alluded to; and all the points in the same surface will be determined by making the like construction for every point in the surface of the sphere. The term of a rational and integral function is not to be strictly confined here to such functions only as consist of a finite number of terms; it may include infinite serieses, provided they are converging ones; and it may even be extended to any algebraic expressions that can be expanded into such serieses. This class of spheroids comprehends the sphere, the ellipsoid, both sorts of elliptical spheroids of revolution, and an infinite number of other figures, as well such as can be described by the revolving of curves about their axes, as others which cannot be so generated. In the second chapter of the third book of the Mécanique Céleste , Laplace has treated of the attractions of spheroids of every kind; and in particular he has given a very ingenious method for computing the attractive forces of that class which in their figures approach nearly to spheres. In studying that work, I discovered that the learned author had fallen into an error in the proof of his fundamental theorem; in consequence of which he has represented his method as applicable to all spheroids whatever, provided they do not differ much from spheres; whereas in truth, when the error of calculation is corrected, and the demonstration made rigorous, his analysis is confined exclusively to that particular kind, described above, which it is proposed to make the subject of this discourse. I have already treated of this matter in a separate paper, in which I have pointed out the source of Laplace’s mistake, and likewise have strictly demonstrated his method for the instances that properly fall within its scope. In farther considering the same subject, it occurred to me that the investigation in the second chapter of the third book of the Mécanique Céleste , however skilfully and ingeniously conceived, is nevertheless indirect, and is besides liable to another objection of still greater weight; it does not exhibit the several terms of the series for the attractive force in separate and independent expressions: it only points out in what manner they may be derived successively, one after another; in so much that the terms of the series near the beginning cannot be found without previously computing all the rest. This remark gave occasion to the following paper, in which it is my design to give a solution of the problem which is not chargeable with the imperfections just mentioned: the analysis is direct, and every term of the series for the attractive force is deduced immediately from the radius of the spheroid. As the ellipsoid, which comprehends both sorts of elliptical spheroids of revolution, falls within the class of figures here treated of, I have derived, as a corollary from my investigation, the formulas for the attractions of that figure which are required in the theory of the earth: this paper therefore will contain all that is useful on the subject of the attractions of spheroids, as far as our knowledge at present extends, deduced by one uniform mode of analysis.

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