Ovule
(ovule), a multicellular formation in the ovary of seed plants, from which, after fertilization, the seed develops. Usually consists of outer and inner covers (instruments). They do not close, leaving a narrow opening - the pollen (micropyle). The integuments cover a multicellular closed layer - the nucellus, in which the embryo sac is enclosed. It, in turn, consists of an egg apparatus - three cells concentrated at the end closest to the pollen. One of them, with a larger nucleus, is an ovum (female gamete), the other two are auxiliary cells, or synerigudas. At the opposite end of the pollen, 3 antipodal cells develop. In the middle of the embryo sac is the central cell. The ovum and the central cell are involved in fertilization.
Encyclopedia Biology. 2012
See also interpretations, synonyms, meanings of the word and what is OVAL in Russian in dictionaries, encyclopedias and reference books:
- Ovule
the same as... - Ovule in the Big Russian Encyclopedic Dictionary:
Ovules, the same as the ovule ... - Ovule in the dictionary of Synonyms of the Russian language.
- Ovule in the Dictionary of the Russian Language Lopatin:
ovule, ... - Ovule in the Complete Spelling Dictionary of the Russian Language:
ovule... - Ovule in the Spelling Dictionary:
ovule, ... - Ovule in Modern explanatory dictionary, TSB:
the same as... - CONIFEROUS in the Encyclopedia of Biology:
, a class of gymnosperms; the largest and most widespread group. Includes 7 families, approx. 55 births and more than 560 ... - OVULE in the Encyclopedia of Biology:
, the same as the ovule ... - PLACENTA in the Encyclopedia of Biology:
1) in placental animals and humans - an organ that provides (through the umbilical cord) communication and metabolism between the body of the mother and the fetus ... - FERTILIZATION in the Encyclopedia of Biology:
, the fusion of male and female germ cells (gametes) in plants, animals and humans, resulting in the formation of a fertilized egg (zygote), ... - OVULE in the Big Encyclopedic Dictionary:
(ovule) the formation in seed plants from which (usually after fertilization) the seed develops. At angiosperms the ovule is located in the cavity of the ovary, ... - PLACENTA in the Big Encyclopedic Dictionary:
(Latin placenta from Greek plakus - cake) (children's place), 1) an organ that communicates and exchanges substances between the mother's body and ... - POLLINATION in the Big Encyclopedic Dictionary:
the transfer of pollen from the anther to the stigma of the pistil in flowering plants or to the ovule in gymnosperms. precedes fertilization. Pollination within... - Yew
(Taxaceae), a family of gymnosperms. Evergreen trees and shrubs, usually strongly branched, mostly needle-shaped, linear or linear-lanceolate, often asymmetrical ... - OVULE in the Great Soviet Encyclopedia, TSB:
ovule, a multicellular formation in seed plants from which a seed develops. The main parts of S. are nucellus, integument (or integuments) ... - SEED in the Great Soviet Encyclopedia, TSB:
ovule, same as ovule... - POLLINATION in the Modern Encyclopedic Dictionary:
- POLLINATION in the Encyclopedic Dictionary:
the transfer of pollen from the anthers to the stigma of the pistil in flowering plants or to the ovule in gymnosperms. It is carried out mainly through…
Questions for a colloquium on the topic
for 2nd year biology students DO
What is an ovule? List its constituent parts in Gymnosperms.
ovule, or ovule(lat. ovulum) - formation in seed plants, from which (usually after fertilization) a seed develops. It is a female sporangium (megasporangium) of seed plants. In gymnosperms - on the surface of the seed scales in female cones, located openly in the axil of the megasporophyll. In the central part of the ovule (nucellus), four megaspores are formed as a result of meiosis of the spore mother cell, then three of them die, and a female gametophyte is formed from one megaspore. In gymnosperms, it is sometimes called the endosperm, since it stores nutrients in the mature seed.
S. consists of a nucellus (central part containing a megasporocyte), one or two integuments (integuments), and a seed stalk (funicular). At the top of the S., the integument usually does not close, leaving a narrow opening, the micropyle.
What is nucellus? How is the laying and development of the ovule?
Nutsellus(from Latin nucella - nut), the central part (core) of the ovule of seed plants; homologous megasporangium ferns. Includes nutrient tissue and a membrane-covered embryo sac with a small opening called micropylem.
Theories of the origin of the ovule integument.
Telomnaya
The integument is the result of the fusion of peripheral initially vegetative telomes around one spore-bearing one. This theory is consistent with paleobotanical findings that refer to protogymnosperms and extinct gymnosperms - seed ferns.
synangial
According to this hypothesis, first put forward by the English paleobotanist Margarita Benson (1908), the integument is a ring of sterilized, fused and fused sporangia surrounding the central functioning megasporangium, and the micropyle corresponds to the initial gap between the tops of the sporangia. In other words, the ovule is in fact a synangium, in which all sporangia, except for one, have become sterilized and form a cover (integument) of a single, fertile sporangium. A good confirmation of the "synancial" hypothesis is the primitive ovules of seed ferns, which often retain very clear traces of their synangial origin. The ovules of a number of seed ferns had segmented integuments with a vascular bundle in each segment (chamber).
Micropylar and chalazal poles of the ovule
In the seed rudiment, the chalaza is located opposite the micropyle, opening the integument. Chalaza is the tissue where the integument and nucellus meet.
The two poles of the embryo correspond to the root and shoot poles.
Embryo: hypocotyl and cotyledons
Features of the ovule as a modified megasporangium of seed plants in comparison with the megasporangium of higher spores.
The seed is a new type of diasporas.
The process of megasporogenesis
On the scales of female cones are 2 ovules. The ovule consists of the nucellus (nucleus) and the integument (cover). A small hole remains at the top - the micropyle (pollen inlet). In late spring, the scales of the female cone open and pollen enters the nucellus through the micropyle. After that, the seed scales are compressed, forming the protection of the ovules. At the time of pollination, there are no male gametes in the speck of dust, and the sprout with archegonia has not yet developed in the ovule. A month after pollination, one of the nucellus cells begins to divide by meiosis. As a result, 4 haploid (n) cells are formed - megaspores. 3 die off, and 1 turns into a growth (n). The female gametophyte is a colorless multicellular thallus. ^ There are many storage substances in the tissue. 14-15 months after pollination, two archegonia are formed on the gametophyte. Archegonium consists of a large egg with a large nucleus, over which lies an early disappearing abdominal tubular cell, and a neck of eight small cells. At this time, the pollen tube grows very slowly inside the nucellus. After the pollen tube with two sperm reaches the archegonium, one of the sperm merges with the egg, the other dies. The embryo develops from the zygote. The ovule turns into a seed. The vegetative body of the female gametophyte becomes the primary endosperm (n). From the nuceus a membranous peel is formed, from the integument - woody. Thus, parts of 3 generations can be distinguished in the seed:
Woody and membranous peel - old sporophyte (2n)
Endosperm - gametophyte (n)
The embryo is a new sporophyte (2n)
A typical variant of the development of the female gametophyte of gymnosperms
What structures are the anthers and pollen grains of gymnosperms homologous to?
Anther - microsporangium, speck - pollen grain
10. 2 variants of the structure of a mature male gametophyte, its cellular elements
11. Further fate of the male gametophyte of gymnosperms.
12. Does the pollen grain always leave the anther mature? Which option is more progressive?
13. Pollination (definition)
In plants, the transfer of pollen from the anthers to the stigma of the pistil (in flowering plants) or to the ovule (in gymnosperms). After O., a pollen tube develops from a speck of dust, which grows towards the ovary and is delivered by the husband. sex cells - sperm - to the egg, located in the ovule, where fertilization and development of the embryo takes place.
14. Fertilization of the cycad type, its features
After pollination, the ovules begin to increase and soon reach the size of a seed, although fertilization has not yet occurred in them. This period, from pollination to fertilization, is very long and usually takes half a year (for example, pollination occurs in December-January, and fertilization in May-June).
Microspores that have entered the pollen chamber with a drop of pollinating fluid germinate. At the same time, the exine bursts and grows through the gap, stretching the intina, the gaustorium cell (Fig. 168, 13). It penetrates into the wall of the pollen chamber and sucks nutrients out of the nucellus tissue (Fig. 168, 13). At this time, the generative cell divides into two, and one of the formed cells - spermatogenic - begins to grow intensively. In it, and not immediately, but after a few months, male gametes are formed - spermatozoa (Fig. 168, 15).
By the time of fertilization, the overgrown spermatogenic cell is in the immediate vicinity of the entrance to the archegonium. The spermatozoa released from it are left to “swim” in the liquid that poured out with them from the spermatogenic cell, only a short distance to the archegonium, in which the contents of the spermatozoon merge with the egg (Fig. 168, 17).
Thus, in cycads, two mechanisms are combined in a single process, one of which - the formation of a mobile spermatozoon - is characteristic of distant ancestors fertilized with the help of water, and the second - the formation of a pollen tube (growing spermatogenic cell) - is typical of all others standing higher on the "evolutionary ladder". » seed plants.
15. Siphonogamy
(fertilization of the pine type) - fertilization with a pollen tube; the sexual process that takes place inside the ovules and does not depend on the presence of moisture. The function of delivering male gametes is carried out by special cells.
16. What is the fundamental difference between these variants of fertilization in gymnosperms?
17. What cells (or their features) in the first and second cases can be called atavistic?
The seed develops on the surface of the seed scale. It is a multicellular structure that combines storage tissue - endosperm, embryo and a special protective cover (seed peel). Before fertilization, the central part of the ovule contains the nucellus, which is gradually replaced by the endosperm. The endosperm is haploid and is formed from the tissues of the female gametophyte.
At cycads and ginkgo the outer layer of the seed coat ( sarcotesta) soft and fleshy, middle layer ( sclerotesta) is solid, and the inner layer(endotest) at the time of maturation of the seed membranous. The seeds are dispersed by various animals that eat the sarcotesta without damaging the sclerotesta.
At yew and podocarpus seeds are surrounded by fleshy aryllus- strongly modified scales of the female cone. The juicy and brightly colored arillus attracts birds that spread the seeds of these conifers. Arillus of many species of podocarpus are also edible for humans.
19. From what structures of the ovule do the corresponding parts of the seed develop?
20. Structures of what stages of the life cycle does the seed include?
22. Compare the structure of the ginkgo seed and pine. What are the signs of the primitiveness of the first?
The developed suspension, characteristic of pines, degenerates by the time of full development of the embryo. A pine seed consists of an embryo, a seed coat and a megagametophyte, which is a store of nutrients.
In cycads and ginkgoes, the outer layer of the seed coat (sarcotesta) is soft and fleshy, the middle layer (sclerotesta) is hard, and the inner layer (endotesta) is membranous by the time the seed ripens.
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Ginkgo ovules platyspermic |
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Additional structures are grouped under the term angiospermization. |
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The pollen chamber is unitegmal |
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Fertilization after abscission |
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23. What is the primary endosperm of the seed? What is its name related to?
The primary endosperm of gymnosperms is formed BEFORE FERTILIZATION from the megaspore and corresponds to the female gametophyte. Gymnosperm endosperm cells are initially haploid, then become polyploid as a result of nuclear fusion.
secondary endosperm- tissue formed in the seeds of most flowering plants DURING FERTILIZATION.
24. Evolutionary advantages of seed reproduction.
Seeds are more viable, thanks to animals, wind, water can be carried over long distances. There is a supply of nutrients, the embryo is protected by seed coats. Reproduction is not related to water.
ovule ovule
ovule, ovule (ovulum), multicellular formation of seed plants, from which the seed develops. Mn. embryologists consider S. a structure homologous to the megasporangium of spore plants. C consists of a nucellus containing a megasporocyte, two or one integument (integument), which, when closed, forms a narrow channel - a micropyle, through which the pollen tube penetrates to the embryo sac, and also a funiculus (seed) that attaches C. to the placenta. The part of S., opposite to the micropyle, is called. chalaza. C. of flowering plants is formed in the ovary. C. gymnosperms are naked, sitting on a megasporophyll. In the chalazal part of S., hypostasis is formed as a result of cell differentiation. For many flowering plants in C. are characterized by obturators—areas of tissue that grow in the form of papillae toward the micropyle and facilitate the penetration of the pollen tube into the embryo sac, its growth, and nutrition. S. is formed on the placenta in the form of a meristematic tubercle. cells from outside epidermis layer; near its apex, one or two archesporial cells (archesporium) appear from the subepidermal layer, and at the base, integuments appear in the form of one or two annular ridges. The megasporocyte (mother cell of megaspores) gives rise to megaspores, of which the lower (chalazal), less often the upper (micropylar) ones give rise to wives. gametophyte (the embryo sac in flowering plants or the primary endosperm in gymnosperms). After fertilization, with the beginning of the development of the embryo, S. turns into a developing seed. Distinguish 5 main. C. types, depending on the location of the micropyle, funiculus, and longitudinal axis of the nucellus: orthotropic, or direct (in buckwheat, pepper, aroid); anatropic, or reversed (the most common type, perhaps the original); hemitropic, or half-turned (in some norichnikov, in primroses); campylotropic, or unilaterally curved (in many species of cloves, legumes, etc.); amphitropic, or bilaterally curved (in some species of the same orders as the previous type). C. with a powerful nucellus, thick, sometimes lignified integuments (the so-called crassinucellate) is considered primitive (predominant in gymnosperms), with a weakly expressed nucellus (tenuinucellate) and with one cover - more progressive, arising from the first by gradual reduction (predominant in flowering). The number of S. in the ovary of flowering plants varies from one (in cereals) to 1 million (in orchids).
.(Source: Biological encyclopedic Dictionary." Ch. ed. M. S. Gilyarov; Editorial: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin and others - 2nd ed., corrected. - M.: Sov. Encyclopedia, 1986.)
ovule(ovule), a multicellular formation in the ovary of seed plants, from which, after fertilization, the seed develops. Usually consists of outer and inner covers (instruments). They do not close, leaving a narrow opening - the pollen (micropyle). The integuments cover a multicellular closed layer - the nucellus, in which the embryo sac is enclosed. It, in turn, consists of an egg apparatus - three cells concentrated at the end of the pollen conduit closest to the pollen. One of them, with a larger nucleus, is an ovum (female gamete), the other two are auxiliary cells, or synerigudas. At the opposite end of the pollen, 3 antipodal cells develop. In the middle of the embryo sac is the central cell. The ovum and the central cell are involved in fertilization.
.(Source: "Biology. Modern Illustrated Encyclopedia." Editor-in-Chief A.P. Gorkin; M.: Rosmen, 2006.)
Synonyms:
See what "OVELS" is in other dictionaries:
The ovules of cycads differ in size (from 5-6 cm in length in some species of cycad to 5-7 mm in dwarf zamia) and in shape. But at the same time, they are quite similar in the main features of development and internal structure. seated openly... Biological Encyclopedia
Semyapochka Dictionary of Russian synonyms. ovule n., number of synonyms: 2 ovule (2) ... Synonym dictionary
Same as ovule... Big Encyclopedic Dictionary
weaving; m. Botan. The germ of the seed; ovule. * * * The ovule is the same as the ovule. * * * Ovule Ovules, the same as the ovule (see. ONUCLES) ... encyclopedic Dictionary
The location of the ovules in the flower of hellebore smelly (Helleborus foetidus) Ovule, or ovule (lat. ... Wikipedia
Ovule ovule, ovule. The multicellular organ of seed plants, from which the seed develops, in angiosperms is formed in the ovary; C. consists of nucellus
ovule- Synonyms: ovule of megasporangia of seed plants, surrounded by one or two covers - integuments. It is formed on megasporophylls or in female strobili (cones) of gymnosperms, in angiosperms - inside the ovary of the pistil of the flower (see ... Plant anatomy and morphology
Same as ovule... Natural science. encyclopedic Dictionary
ovule- ovule atok, tka ... Russian spelling dictionary
Ovule- ovule (ovulum), a multicellular formation in the reproductive organs of seed early, from which a seed develops during development (usually after fertilization). In angiosperms, S. is formed hidden inside the ovary, in gymnosperms it is located ... ... Agricultural Encyclopedic Dictionary
its location in the body cavity. What organ system does it belong to? Where are the kidneys located in fish, in which body cavity? What organ system do they belong to? What function do they perform?
1. where are the lungs located? what is their structure?2. Why is each lung in a hermetically sealed space?
3. The pulmonary pleura has elasticity: it continuously stretches and contracts. Due to what fabric is this possible?
4. What is common and what is the difference between gas exchange in the lungs and tissues?
1. What is called an escape?
a) a plant without a root; b) method of plant propagation; c) a stem with leaves and buds located on it; d) plant science; e) flowering at least once in a lifetime.
2. What attracts pollinating insects to a flower?
a) stamens and pistils; b) pestle; c) a cup; d) cup and whisk; e) calyx and pedicel.
3. What is indicated by the number 4?
a) a flower b) stem; c) sheet; d) roots; e) seeds.
4. Who invented the first microscope?
a) Leonardo da Vinci b) Aristotle; c) I. P. Pavlov; d) Antonio Van Leeuwenhoek; e) Democritus.
5. What is the name of the simplest magnifying device that gives an increase of 2-25 times?
a) a magnifying glass b) electron microscope; c) a magnifying glass; d) microscope; e) eyepiece.
6. What is indicated by the number 4?
a) shell; b) core; c) vacuole; d) cytoplasm; e) pores.
7. What are green plastids called?
a) cytoplasm; b) core; c) chloroplasts; d) pores; e) vacuole.
8. What number indicates the vacuoles?
a) 1; b) 2; at 3; d) 4; e) 5.
9. What is the name of the root that develops from the root of the embryo?
a) accessory; b) lateral; c) main; d) additional; e) embryonic.
10. What is soil?
a) plant habitat; b) the place where the roots of flowering plants grow; c) a mixture of clay, humus, sand; d) the upper, loose, fertile layer of the earth on which plants grow; e) upper, loose, fertile layer of the lithosphere.
11. Which plant has a fibrous root system?
a) peas; b) beans; c) beans; d) wheat; e) carrots.
12. What is indicated by the number 4?
a) kidney scales; b) rudimentary stem; c) germinal leaf; d) rudimentary escape; e) embryonic bud.
13. Due to division, which cells do the apical and intercalary growth of plant shoots occur?
a) internodes; b) growth cone; c) growth cones and internodes; d) growth cone and leaf bases; e) roots.
14. What is the function of leaves?
a) air supply and gas exchange; b) reproduction and storage of substances; c) transport of substances and reproduction; d) evaporation of water and transport of substances; e) attract insects.
15. What number indicates the stomatal fissure?
a) 14 b) 2; at 3; d) 4; e) 5.
16. What is an annual ring?
a) all layers of wood formed in spring, summer and autumn;
b) growth of plants in one year; c) rings on a tree cut; d) a narrow layer of cells with thin membranes; e) a layer of cells under the cortex.
17. In what part of the woody stem does the accumulation of reserve substances occur?
a) in the cambium; b) in wood; c) in the core; d) in the cortex; e) in the luba.
18. What is the function of the peel and cork?
a) protective; b) educational; c) storage; d) mechanical.
19. What is shown in the figure by the number 4?
a) stigma; b) pestle; c) column; d) cup; e) anther.
20. Where are the ovules (ovules) located?
a) in stamens; b) in the receptacle; c) in the ovary; d) in the stigma; d) petals.
