| 单词 | micropyle |
| 例句 | When a pollen grain reaches the stigma, a pollen tube extends from the grain, grows down the style, and enters through the micropyle: an opening in the integuments of the ovule. Fundamentals of Biology 2015-01-01T00:00:00Z Inverted and straight, with the micropyle next the hilum and the radicle consequently inferior. The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee 2012-04-12T02:00:30.140Z At one end a cap-like portion of this forms a detachable operculum, in the middle of which is a minute opening, the micropyle. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8 "Cube" to "Daguerre, Louis" 2012-01-31T03:00:17.257Z The female flower is enveloped in a closely fitting sac-like investment, which must be regarded as a perianth; within this is an orthotropous ovule surrounded by a single integument prolonged upwards as a beak-like micropyle. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" 2011-12-26T03:00:11.613Z This is seen in the passion-flower, where the covering arises from the placenta or extremity of the funicle at the base of the ovule and passes upwards towards the apex, leaving the micropyle uncovered. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z An opening called a micropyle allows entry of the pollen tube from the base. Fundamentals of Biology 2015-01-01T00:00:00Z Seeds globular, with a crustaceous coat, ascending, imperfectly anatropous, the rhaphe not adherent quite down to the micropyle, the persistent seed-stalk thus forming a sort of lateral beak. The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee 2012-04-12T02:00:30.140Z The micropyle indicates the organic apex of the ovule. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 5 "Fleury, Claude" to "Foraker" 2011-04-03T02:00:20.883Z A complete and functional female flower consists of a single ovule with two integuments, the inner of which is prolonged into a narrow tubular micropyle, like that in the flower of Gnetum. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" 2011-12-26T03:00:11.613Z The base of the nucellus is indicated by the chalaza ch, while the apex is at the micropyle m. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z The integuments, while protecting the megasporangium, do not enclose it completely, but leave an opening called the micropyle. Fundamentals of Biology 2015-01-01T00:00:00Z The pollen-tube does not penetrate the ovule through the micropyle but enters at the opposite end—the chalaza. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 4 "Carnegie Andrew" to "Casus Belli" The ovule is curved upon itself, so that the micropyle is near the funicle. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 5 "Fleury, Claude" to "Foraker" 2011-04-03T02:00:20.883Z A young ovule consists of a conical nucellus surrounded by a single integument terminating as a two-lipped micropyle. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" 2011-12-26T03:00:11.613Z Hence, by ascertaining the position of the micropyle and chalaza, the two extremities of the embryo can in general be discovered. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z Three nuclei position themselves on the end of the embryo sac opposite the micropyle and develop into the antipodal cells, which later degenerate. Fundamentals of Biology 2015-01-01T00:00:00Z Every ovule has a tiny opening, or micropyle as it is called, and it is now easy to guess what that is for. The Renewal of Life; How and When to Tell the Story to the Young In angiosperms when the pollen-tube reaches the micropyle it passes down into the canal, and this portion of it increases considerably in size. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 5 "Fleury, Claude" to "Foraker" 2011-04-03T02:00:20.883Z Secondine and nucleus, with the bulbous end that projects through the micropyle. Vegetable Teratology An Account of the Principal Deviations from the Usual Construction of Plants This arillode, after growing downwards, may be reflected upwards so as to cover the micropyle. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z The micropyle allows the pollen tube to enter the female gametophyte for fertilization. Fundamentals of Biology 2015-01-01T00:00:00Z This opening is called the “micropyle,” and allows the pollen tube to enter. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses The integuments do not completely invest the apex of the nucellus, but an opening termed the micropyle is left. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 5 "Fleury, Claude" to "Foraker" 2011-04-03T02:00:20.883Z In Casuarina, Juglans and the order Corylaceae, the pollen-tube does not enter by means of the micropyle, but passing down the ovary wall and through the placenta, enters at the chalazal end of the ovule. Encyclopaedia Britannica, 11th Edition, Volume 2, Part 1, Slice 1 At the micropyle in the bean is observed a small process of integument, which, when the young plant sprouts, is pushed up like a lid; it is called the embryotega. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z The integument contains an opening called the micropyle, through which the pollen tube enters the embryo sac. Fundamentals of Biology 2015-01-01T00:00:00Z By carefully opening the ovary and slightly crushing it in a drop of water, the pollen tube may sometimes be seen growing along the stalk of the ovule until it reaches and enters the micropyle. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses In such an ovule a straight line drawn from the hilum to the micropyle passes along the axis of the ovule. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 5 "Fleury, Claude" to "Foraker" 2011-04-03T02:00:20.883Z Such a method of entrance is styled chalazogamic, in contrast to the porogamic or ordinary method of approach by means of the micropyle. Encyclopaedia Britannica, 11th Edition, Volume 2, Part 1, Slice 1 The radicular extremity points towards the micropyle, while the cotyledonary extremity is pointed towards the base of the ovule or the chalaza. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z I know it is not new; but how wonderful his account of the spermatozoa of some dioecious alga or conferva, swimming and finding the minute micropyle in a distinct plant, and forcing its way in! More Letters of Charles Darwin — Volume 2 In these two points, the reception of the pollen by the micropyle and the nursing of the embryo, it appears that many Palaeozoic seeds were imperfect, as compared with the typical seeds of later times. Darwin and Modern Science Again, in others I found small mammillary bodies, which appeared to be true ovules, though I could not perfectly satisfy myself as to the existence of the micropyle or nucleus. More Letters of Charles Darwin — Volume 2 The primary root of the embryo in all Angiosperms points towards the micropyle. Encyclopaedia Britannica, 11th Edition, Volume 2, Part 1, Slice 1 It has been already stated that the radicle of the embryo is directed to the micropyle, and the cotyledons to the chalaza. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z If I have time I will have another look at pollen-tubes, as, from what you say, they ought to find their way to the micropyle. More Letters of Charles Darwin — Volume 2 |
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