| 单词 | antheridium |
| 例句 | Male antheridia and female archegonia grow at the tip of the stem. Fundamentals of Biology 2015-01-01T00:00:00Z Sperm are produced in antheridia and need standing water to swim to the eggs to form a diploid zygote. Miller & Levine Biology 2018-01-01T00:00:00Z Once released from the antheridium, the clock begins to count down their survival probability. How Mosses Have Sex in Spite of Their Swimming-Challenged Sperm 2012-07-28T11:45:00.203Z One of the minute organs developed in an antheridium, corresponding to pollen-grains. 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 One of the mobile male reproductive bodies in the antheridia of cryptograms. Webster's Unabridged Dictionary 2012-03-24T02:00:23.513Z In the sexual life cycle, a round structure called an antheridium buds from the male strain, and a similar structure called the ascogonium buds from the female strain. Fundamentals of Biology 2015-01-01T00:00:00Z The sperm and eggs are produced on gametophytes in antheridia and archegonia, and fertilization requires a thin film of water, so that the sperm can swim to the eggs. Miller & Levine Biology 2018-01-01T00:00:00Z The sperm need all the help they can get in moving toward the egg, seldom travelling more than four inches from the structure called an antheridium that produced them. How Mosses Have Sex in Spite of Their Swimming-Challenged Sperm 2012-07-28T11:45:00.203Z Cryptogamous plants with a distinct axis or stem, growing from the apex, and commonly not with later increase in diameter, usually furnished with distinct leaves; reproduction by antheridia and archegonia, sometimes also by gemmation. 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 endochrome is believed to be fertilized by bodies developed in antheridia, the contents of each fertilized cell dividing into four ovate zoospores. Sea-Weeds, Shells and Fossils 2011-08-20T02:00:11.557Z The “male” strain produces an antheridium and the “female” strain develops an ascogonium. Fundamentals of Biology 2015-01-01T00:00:00Z In Cystopus Bliti the oosphere contains numerous nuclei, and all the male nuclei from the antheridium pass into it, the male and female nuclei then fusing in pairs. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z The plants are of three kinds, viz. ♂, bearing antheridia; ♀, bearing oogonia; and neuter, producing tetraspores. The New Gresham Encyclopedia Volume 4, Part 1: Deposition to Eberswalde 2011-04-14T02:00:57.977Z Thallus decumbent, irregularly lobed, 1–2´ long, 3–5´´ wide; involucre none; pedicel ¾–1´ long, sometimes folded upon itself and remaining within the calyptra, the capsule thus appearing sessile; antheridia on elongated receptacles.—Wooded swamps. 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 Middle portion of the young one, much magnified, showing below, partly among the rootlets, the antheridia or fertilizing organs, and above, near the notch, three pistillidia to be fertilized. The Elements of Botany For Beginners and For Schools Flagellated sperm released from the antheridium swim on a wet surface to the archegonium, where the egg is fertilized. Fundamentals of Biology 2015-01-01T00:00:00Z The ordinary mycelium is the gametophyte since it bears the ascogonia and antheridia when present; the ascogenous hyphae with their asci represent the sporophyte since they are derived from the fertilized ascogonium. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 "Frost" to "Fyzabad" 2011-08-15T02:00:28.473Z At the base of these oocysts appear the presumed antheridia, that is to say, one or two slender filaments, which generally turn their extremities towards the oocysts, and which more rarely are applied to them. Fungi: Their Nature and Uses It is called an “antheridium,” and within are produced, by internal division, numerous excessively small spermatozoids. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses A fruiting portion, magnified, showing the structure; a sporocarp, and an antheridium. The Elements of Botany For Beginners and For Schools The gametophyte contains antheridia that produce, sperm and archegonia that produce eggs. Fundamentals of Biology 2015-01-01T00:00:00Z When mature the antheridium opens on being moistened and the spermatozoids become free in the water by the dissolution of the mucilaginous cell-walls enclosing them. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" After the evacuation of the antheridia the gonospheres are found to be covered with cellulose; they then constitute so many oospores, with solid walls. Fungi: Their Nature and Uses Unlike the antheridium, the oögonia contain a great deal of chlorophyll, appearing deep green. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses The fructification consists of a globular sporocarp of considerable size, which is spirally enwrapped by tubular cells twisted around it: by the side of this is a smaller and globular antheridium. The Elements of Botany For Beginners and For Schools This becomes the organ termed the antheridium, from its analogy in function to the anther of flowering plants. Scientific American Supplement, No. 460, October 25, 1884 Each antheridium or archegonium arises from a single cell, and while the mature structure is similar in the two groups, the development presents differences in liverworts and mosses. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" These particles become globose cells, grouped in the centre of the antheridium. Fungi: Their Nature and Uses The diameter of the antheridium now increases rapidly, and the central cells separate, leaving a large space within. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses A bursting antheridium, and some of the accompanying jointed threads, highly magnified. The Elements of Botany For Beginners and For Schools The upper part of the antheridium becomes separated from the parent stem by a septum, and its contents are converted into ciliated motile antherozoids. Scientific American Supplement, No. 460, October 25, 1884 The individual antheridia are sunk in depressions from which the spermatozoids are in some cases forcibly ejected. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" Afterwards the contents of these latter cells become divided into numerous bacillary spermatozoids, which first break the wall of their mother cell, and then issue from the antheridium. Fungi: Their Nature and Uses The yellow masses are masses of antheridia; the round bodies, the oögonia. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses The minute motile filaments of the antheridia fertilize the large spores after injection into the water: and then the latter promptly acquire a cell-wall and germinate. The Elements of Botany For Beginners and For Schools At the top of the axis in the male plant rise the antheridia, surrounded by an envelope of modified leaves called the perigonium. Scientific American Supplement, No. 531, March 6, 1886 The small thallus bears the antheridia and archegonia, each of which is surrounded by a tubular involucre, on the upper surface of distinct individuals. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" These same fruits, he says, which owe their origin to sexual organs, should bear the names of oogonia and antheridia, according to the terminology proposed by Pringsheim for analogous organs in the Algæ. Fungi: Their Nature and Uses K, mass of spermatozoids surrounded by the inner membrane of the antheridium. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses The antheridium consists at first of a basal cell and a terminal one. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses The antheridia are stalked sacs, with a single wall of cells, and the spiral antherozoids arise by free-cell formation from the cells of the interior. Scientific American Supplement, No. 531, March 6, 1886 The antheridia are protected by leaves which are often modified in shape. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" The slightly thickened membrane of the antheridia encloses protoplasm which is finely granular. Fungi: Their Nature and Uses The antheridium undergoes no further change, but the archicarp soon divides into two cells,—a small basal one and a larger upper cell. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses These cells, especially the outer ones, develop a great amount of a red pigment, giving the antheridium its characteristic color. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses They are discharged by the bursting of the antheridium, together with a mucilage formed of the degraded walls of their mother cells. Scientific American Supplement, No. 531, March 6, 1886 The stalked globular antheridia are exceptional in being formed endogenously, and are situated in groups in special intercellular spaces. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" It is seldom that more than one antheridium applies itself to an oogonium. Fungi: Their Nature and Uses The small side branchlets bear the antheridia, × 2. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses If a ripe antheridium is crushed in a drop of water, after lying a few minutes the spermatozoids will escape through small openings in the side of the cells. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses The sexual generation is a small green thalloid structure called a prothallium, which bears antheridia and archegonia, each archegonium having a neck-canal and oosphere, which is fertilized just as in the moss. Scientific American Supplement, No. 531, March 6, 1886 The superficial layer of cells bounding the cavity does not break down until the antheridia are nearly mature. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" It is remarkable that amongst these fungi the tube projected by the antheridium effects fecundation only by contact. Fungi: Their Nature and Uses When ripe, if brought into water, the antheridium bursts at the top into a number of irregular lobes that curl back and allow the mass of sperm cells to escape. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses The act of fertilization may be easily observed by laying fresh antheridia into a drop of water containing recently discharged egg cells. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses Within a few minutes after putting the oögonia into water, the egg cells may be seen to escape into the water, when some of the antheridia may be added. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses Occasionally antheridia develop on the surface of shaded portions of the thallus. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" Its extremity never opens, and we never find antherozoids; on the contrary, the antheridium presents, up to the maturity of the oospore, the appearance which it presented at the moment of fecundation. Fungi: Their Nature and Uses In studying the development of the antheridia, it is only necessary to mount the plants in water and examine them directly; but the study of the archegonia requires careful longitudinal sections of the prothallium. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses If these are carefully separated, the antheridia can just be seen as minute whitish globules, barely visible to the naked eye. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses K, L, young antheridia, in optical section, × 300. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses The sexual organs, with the exception of the antheridia of Sphagnum, are borne at the apices of the main shoot or of branches. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" This new septum defines a terminal short obtuse cell, the antheridium, which is thus borne on a narrow tube like a sort of pedicel. Fungi: Their Nature and Uses Under favorable conditions, the first antheridia are ripe in about five weeks; the archegonia, which are borne on separate plants, a few weeks later. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses N, O, antheridia that have partially discharged their contents, × 300. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses B, a small spore of Pilularia, with the ripe antheridium protruding, × 180. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses Their general similarity to the mature antheridia and archegonia of liverworts and the main difference in their development have been referred to. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" Immediately after the formation of the antheridia new productions show themselves, both around the oocyst and within it. Fungi: Their Nature and Uses When ripe, the antheridium opens at the end and discharges the spermatozoids, which are, however, so very small as scarcely to be visible except with the strongest lenses. Elements of Structural and Systematic Botany For High Schools and Elementary College Courses The antheridia are globular and have long stalks. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" The male plant has no definite stem, and consists of a single concave leaf protecting the antheridium. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" The antheridia open by means of a cap cell or groups of cells with mucilaginous contents. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" The antheridium remains for a long time recognizable without undergoing any essential modification, but the dark colour of the perithecium soon hides it from the observer’s eye. Fungi: Their Nature and Uses |
| 随便看 |
|
英语例句辞典收录了117811条英语例句在线翻译词条，基本涵盖了全部常用单词及词组的例句翻译及用法，是英语学习的有利工具。