| 单词 | allantois |
| 例句 | The allantois stores nitrogenous wastes produced by the embryo and also facilitates respiration. Fundamentals of Biology 2015-01-01T00:00:00Z Some grow to form the extra-embryonic membranes needed to support and protect the growing embryo: the amnion, the yolk sac, the allantois, and the chorion. Anatomy and Physiology 2013-06-19T00:00:00Z The division of Vertebrata in which the embryo develops an allantois. Webster's Unabridged Dictionary 2012-03-24T02:00:23.513Z In Mammalia the allantois is not so largely developed as in Birds, and it enters largely into the formation of the placenta. The New Gresham Encyclopedia. Vol. 1 Part 1 A to Amide The third is the chorion, forming the outer membrane which encloses the fetus, and within which is the amnion, or innermost membrane which surrounds the fetus, and between which is another membrane, called the allantois. What a Young Husband Ought to Know The allantois stores nitrogenous waste and facilitates respiration. Fundamentals of Biology 2015-01-01T00:00:00Z Together, the stalks of the yolk sac and allantois establish the outer structure of the umbilical cord. Anatomy and Physiology 2013-06-19T00:00:00Z The division of Vertebrata in which no allantois is developed. Webster's Unabridged Dictionary 2012-03-24T02:00:23.513Z Diagram of chick showing relations of amnion, allantois and yolk. A Critique of the Theory of Evolution The literal references to the foregoing are: am, amnion; al, allantois; v, vitellus; h, encephalon; i, eye; c, heart; f, liver; g, gizzard; ms, upper, and mi, lower member. Was Man Created? The allantois is composed of two layers, which form a closed sac in connection with the urachus, or the tube which extends from the fetal bladder through the umbilical cord. Special Report on Diseases of Cattle Four embryonic membranes form to support the growing embryo: the amnion, the yolk sac, the allantois, and the chorion. Anatomy and Physiology 2013-06-19T00:00:00Z The fasciculus attached to the embryo is the allantois which becomes the umbilical cord. The Sexual Question A Scientific, psychological, hygienic and sociological study Her blood seeps over into the transformed allantois which is now called a placenta. The Meaning of Evolution The union of the allantois and the gut accounts for the elongated outline of the enteron in this section. Development of the Digestive Canal of the American Alligator The allantois also contains a fluid which is known as the allantoid liquid. Special Report on Diseases of Cattle Figures to illustrate the relative function and importance of allantois and yolk sac in bird and mammal. Text Book of Biology, Part 1: Vertebrata Thus in many mammals the mesodermal part of the allantois often appears long before the endodermal part, though this is phylogenetically older. Form and Function A Contribution to the History of Animal Morphology So the allantois of the reptile has become the placenta of the mammal. The Meaning of Evolution Just anterior to these openings the cloaca opens ventrally into a small, anteriorly-projecting pouch, the rudiment of the allantois. Development of the Digestive Canal of the American Alligator In the uterus the fetus is surrounded by several membranes which are known as the amnion or inner layer, the allantois or central layer, and the chorion or outer layer. Special Report on Diseases of Cattle The structure thus formed by the union of the wall of the maternal uterus, allantois, and the intermediate structures is called the placenta. Text Book of Biology, Part 1: Vertebrata And, given the marsupial mode of development and an embryo possessing an allantois, it is almost a physiological necessity that in some forms at least a placenta should develop. 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 The allantois of the chick now gains a new development and an altered function. The Meaning of Evolution The allantois, al, extends cephalad for some distance from the floor of the cloaca. Development of the Digestive Canal of the American Alligator The one layer of the allantois is spread over the outer surface of the amnion and the other over the inner surface of chorion. Special Report on Diseases of Cattle At an early stage, the outgrowing allantois, pushing in front of it the serous membrane, is closely applied to the lining of the mother's uterus. Text Book of Biology, Part 1: Vertebrata An embryonic appendage, the allantois, used in reptiles and birds for respiration, has here been turned to another purpose. 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 It draws its oxygen and throws off its wastes through the instrumentality of the allantois, which covers it over. The Meaning of Evolution In the region of the posterior appendages, pa, the section passes through the hindgut, hg, and allantois, al. Development of the Digestive Canal of the American Alligator These eggs are objectionable to the fastidious housewife, because of the appearing of the white and scummy looking allantois on the yolk. The Dollar Hen Blood is taken out to the allantois, however, by the arteries of the latter type. Text Book of Biology, Part 1: Vertebrata This is the placenta, developed, in part from the allantois of the embryo, in part from the uterus of the mother. 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 The blood vessels of the allantois take in oxygen and give out carbon dioxide through the porous shell. The Meaning of Evolution Ventrad to the large intestine, and almost in contact with it, is seen the allantois, al, whose general outline was noted in connection with figure 7. Development of the Digestive Canal of the American Alligator The embryos of Reptiles, Birds, and Mammals all develop two embryonic or foetal membranes, the amnion and the allantois. Hormones and Heredity In the fowl, however, the blood-vessels of the allantois also probably absorb the albumen of the egg, and may excrete urea into the egg-space. Text Book of Biology, Part 1: Vertebrata Covering the external face of the amnion and lining the inner face of the chorion is a double membrane, the allantois. Common Diseases of Farm Animals The ancestors of these Amniotes develop an amnion and allantois, and gradually assume the mammal, and finally the specifically human, form. The Evolution of Man — Volume 2 The allantois is probably somewhat larger here than in the other embryos used for this stage, in which it was torn away. Development of the Digestive Canal of the American Alligator It is impossible to reconcile the conception of mutation with the adaptive relation between this allantois and the expulsion of the egg enclosed in a shell on land. Hormones and Heredity From the hinder end of the fowl's intestine, in a position corresponding to the so-called, urinary bladder of the frog, a solid outgrowth, the allantois, which speedily becomes hollow, appears. Text Book of Biology, Part 1: Vertebrata Immediately surrounding it is the liquor amnii, and within allantois is the allantoic fluid. Common Diseases of Farm Animals It is very probable that the urinary bladder of the Dipneusts is the first structure of the allantois. The Evolution of Man — Volume 2 The allantois is cut near its opening into the hindgut; its walls 14 are thin, the epithelium consisting of but a single layer of more or less flattened cells. Development of the Digestive Canal of the American Alligator It seems possible that it is merely the mechanical result of the weight of the embryo and the development of the allantois. Hormones and Heredity We find solid mesoblastic somites, we find primitive streak, allantois and amnion, features we have just been explaining as the consequence of an excess of yolk in the egg. Text Book of Biology, Part 1: Vertebrata When the allantois has attached itself to the inner wall of the chorion and been converted into the placenta, its blood-vessels alone effect the nourishment of the embryo. The Evolution of Man — Volume 1 The thin wall of the allantois consists of the same two layers or membranes as the wall of the gut—the gut-gland layer within and the gut-fibre layer without. The Evolution of Man — Volume 2 From the ventral wall of the large intestine, at a point about one-third the distance from the cloaca to the caecum, projects ventrad and cephalad the stalk of the allantois, al. Development of the Digestive Canal of the American Alligator One of the most obvious examples of this is the allantois in the Amniota. Hormones and Heredity But the allantois and yolk sac of the rabbit, though they correspond in development, differ entirely in function from the similar organs of the fowl. Text Book of Biology, Part 1: Vertebrata The further development of the allantois varies considerably in the three sub-classes of the mammals. The Evolution of Man — Volume 1 The formation of the amnion and the allantois and the complete disappearance of the gills are the chief characteristics that distinguish the Amniotes from the lower Vertebrates we have hitherto considered. The Evolution of Man — Volume 2 Owing to its thin walls and small lumen the allantois was traced only a short distance into the umbilical stalk. Development of the Digestive Canal of the American Alligator They act for a time as kidneys, absorbing unusable juices from the embryonic body and conducting them to the cloaca—afterwards to the allantois. The Evolution of Man — Volume 2 For a clear understanding of the allantois and amnion, this last is almost indispensable. Text Book of Biology, Part 1: Vertebrata The wall of the allantois and the enveloping serolemma remains smooth and without villi, as in the birds. The Evolution of Man — Volume 1 Two of these embryonic structures, the yelk-sac and allantois, are already known to us. The Evolution of Man — Volume 2 There the primitive urine accumulates, and thus the allantois acts as bladder or urinary sac in the embryos of man and the other Amniotes. The Evolution of Man — Volume 2 In this most advanced group of the mammals the allantois is very small, soon loses its cavity, and then, in common with the amnion, undergoes certain peculiar changes. The Evolution of Man — Volume 1 This is the allantois or "primitive urinary sac," an important embryonic organ, only found in the three higher classes of vertebrates. The Evolution of Man — Volume 1 The gut-fibre layer of the allantois, richly supplied with branches of the umbilical vessel, presses into these tufts of the primary chorion, and forms the "secondary chorion." The Evolution of Man — Volume 1 As the permanent kidneys grow rapidly and advance forward, their passage, the ureter, detaches altogether from its birth-place, the posterior end of the nephroduct; it passes to the posterior surface of the allantois. The Evolution of Man — Volume 2 These vessels naturally atrophy with the degeneration of the umbilical vesicle, and the vitelline circulation is replaced by a second, that of the allantois. The Evolution of Man — Volume 1 The allantois has grown out of the gut behind. The Evolution of Man — Volume 1 We now know from Selenka that the much-discussed ventral pedicle is merely the pedicle of the allantois, combined with the pedicle of the amnion and the rudimentary pedicle of the yelk-sac. The Evolution of Man — Volume 1 Two of these appendages—the amnion and the allantois—are only found in the three higher classes of vertebrates, while the third, the yelk-sac, is found in most of the vertebrates. The Evolution of Man — Volume 1 Phylogenetically we must suppose that the allantois originated as a pouch-like growth from the cloaca-wall in consequence of the expansion caused by the urine accumulated in it and excreted by the kidneys. The Evolution of Man — Volume 2 But the other two vesicles, the yelk-sac and the allantois, are equipped with large blood-vessels, and these effect the nourishment of the embryonic body. The Evolution of Man — Volume 1 |
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