| 单词 | blastopore |
| 例句 | Upon gastrulation, part of the ball of cells invaginates, forming a cavity called a blastopore. Fundamentals of Biology 2015-01-01T00:00:00Z It has usually been regarded as representing both endoderm and mesoderm, and the groove which usually leads to its formation has been compared to the abnormally elongated blastopore of a typical gastrula. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 4 "Hero" to "Hindu Chronology" 2012-04-04T02:00:56.447Z The blastopore persists as the anal opening of the adult. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8 "Cube" to "Daguerre, Louis" 2012-01-31T03:00:17.257Z The blastopore generally occupies a position corresponding to the posterior end of the body. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z Then the large cells recommence the process of division and sink into the hollow of the sphere, leaving an elongated groove, the blastopore, on the surface. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5 "Gassendi, Pierre" to "Geocentric" 2011-09-02T02:00:20.450Z Recent evidence has challenged this view of the development of the blastopore of protostomes, however, and the theory remains under debate. Fundamentals of Biology 2015-01-01T00:00:00Z In the above-mentioned abnormal development of the frog's egg it happened that one edge of the blastopore, on account of its weight, was very much bent outwards. The Biological Problem of To-day Preformation Or Epigenesis? The Basis of a Theory of Organic Development 2011-08-29T02:01:04.170Z It is no doubt the impress of some remarkable larval condition of the blastopore of a stage of evolution now long past. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z Segmentation is total and at first regular, and is followed by invagination, the blastopore passing to the position of the future mouth. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 2 "Chicago, University of" to "Chiton" When the middle and hinder regions of the blastopore are closing in, an equatorial ridge of ciliated cells is formed, converting the embryo into a typical trochosphere. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5 "Gassendi, Pierre" to "Geocentric" 2011-09-02T02:00:20.450Z Animals belonging to superphylum Lophotrochozoa are protostomes, in which the blastopore, or the point of involution of the ectoderm or outer germ layer, becomes the mouth opening to the alimentary canal. Fundamentals of Biology 2015-01-01T00:00:00Z In consequence of this the cleft of the blastopore lay between the normal blastopore-lip and the everted border of the other lip. The Biological Problem of To-day Preformation Or Epigenesis? The Basis of a Theory of Organic Development 2011-08-29T02:01:04.170Z These thickened tracts of ectoderm in Peripatus and a few other forms can be clearly seen to surround the blastopore. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The inner layer we call the entoderm, the outer the ectoderm; and the "primitive mouth" is known as the blastopore. The World's Greatest Books — Volume 15 — Science The blastopore now closes along the middle part of its course, which coincides in position with the future “foot.” Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5 "Gassendi, Pierre" to "Geocentric" 2011-09-02T02:00:20.450Z In deuterostomes, two groups of gastrula cells in the blastopore grow inward to form the mesoderm. Fundamentals of Biology 2015-01-01T00:00:00Z The notochord arises from a set of cells which are in close relation with the fused tips of the blastopore. The Biological Problem of To-day Preformation Or Epigenesis? The Basis of a Theory of Organic Development 2011-08-29T02:01:04.170Z This cup-stage is called the gastrula stage; the outer wall of the gastrula is the ectoderm, and its inner the endoderm; while its cavity is the enteron, and the opening to the exterior the blastopore. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The entoderm, which has the appearance of being thickened because of the fact that the notochord has not yet completely separated from it, is continuous, through the blastopore, with the ectoderm. Development of the Digestive Canal of the American Alligator One end of the blastopore becomes nearly closed, and an ingrowth of ectoderm takes place around it to form the stomodaeum or fore-gut and mouth. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5 "Gassendi, Pierre" to "Geocentric" 2011-09-02T02:00:20.450Z The blastopore is the indentation formed during the initial stages of gastrulation. Fundamentals of Biology 2015-01-01T00:00:00Z The primitive streak is, in fact, the scar of a closed blastopore. Text Book of Biology, Part 1: Vertebrata On the contrary, there are distinct reasons for thinking that the Vertebrate mouth is a derivate of the blastopore. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z Posterior to the blastopore 2 the primitive streak, ps, is seen as a collection of scattered cells between the ectoderm and the entoderm, apparently formed by proliferation from the ventral side of the ectoderm. Development of the Digestive Canal of the American Alligator In other respects Sedgwick's speculations link on more closely to the Gastræa theory, for one of his main contentions is that the blastopore or Urmund is homologous throughout at least the three metameric phyla. Form and Function A Contribution to the History of Animal Morphology The archenteron develops into the alimentary canal, and a mouth opening is formed by invagination of ectoderm at the pole opposite the blastopore of the gastrula. Fundamentals of Biology 2015-01-01T00:00:00Z Figure 6 shows a slightly later ovum than Figure 5, seen from the dorsal side. b.p. is the blastopore. Text Book of Biology, Part 1: Vertebrata Here there is always found at the lips of the blastopore, and extending for a short distance inwards as enteric lining, a certain amount of tissue, which by its characters must be regarded as ectoderm. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The foregut is here more inclosed, and the notochord, nt, having separated from the entoderm, en, is seen as a distinct layer of cells extending from the foregut to the blastopore. Development of the Digestive Canal of the American Alligator Outer layer is the ectoderm; inner layer, the entoderm; internal cavity, the archenteron; mouth of cavity, blastopore. The Whence and the Whither of Man A Brief History of His Origin and Development through Conformity to Environment; Being the Morse Lectures of 1895 By a comparison of the figures of frog and fowl the student will easily perceive the complete correspondence of the position of this with the blastopore of the frog. Text Book of Biology, Part 1: Vertebrata Figure 9 gives a similar diagram of a later stage, but here the blastopore is closed. Text Book of Biology, Part 1: Vertebrata This stage is called the gastrula stage; ar. is the cavity of the gastrula, the archenteron; b.p. is its opening or blastopore. Text Book of Biology, Part 1: Vertebrata The space occupied by the yolk corresponds to the archenteron or primitive digestive cavity; and the opening at the end to the primitive mouth or blastopore. The Whence and the Whither of Man A Brief History of His Origin and Development through Conformity to Environment; Being the Morse Lectures of 1895 |
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