英语词汇“coelom”造句的方法、技巧、例句及翻译-英语例句辞典

This layer multiplies into a band and then splits internally to form the coelom; this protostomic coelom is hence termed schizocoelom. Fundamentals of Biology 2015-01-01T00:00:00Z

A true coelom arises entirely within the mesoderm germ layer. Concepts of Biology 2013-04-25T00:00:00Z

Beating cilia at the opening of the nephridium draw water from the coelom into a tubule. Biology for AP Courses 2022-06-09T00:00:00Z

Most complex animals have a body cavity, or coelom. Miller & Levine Biology 2018-01-01T00:00:00Z

The kidney duct is seen running along the roof of the coelom on either side. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8 "Cube" to "Daguerre, Louis" 2012-01-31T03:00:17.257Z

These animals possess a true coelom that is modified into a unique circulatory system called a water vascular system. Fundamentals of Biology 2015-01-01T00:00:00Z

Other developmental characteristics differ between protostomes and deuterostomes, including the mode of formation of the coelom and the early cell division of the embryo. Concepts of Biology 2013-04-25T00:00:00Z

These organisms produce sperm and eggs from undifferentiated cells in their coelom and store them in that cavity. Biology for AP Courses 2022-06-09T00:00:00Z

Development shows that the glandular tube is mesoblastic in origin and is of the nature of a coelomoduct, while the end-sac is to be regarded as a vestigial portion of the coelom. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z

When the pus escapes from the tubes into the coelom it sets up pelvic peritonitis. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" 2011-12-26T03:00:11.613Z

The presence of a coelom affords many advantages, and animals with a coelom may be termed true coelomates or pseudocoelomates, depending on which tissue gives rise to the coelom. Fundamentals of Biology 2015-01-01T00:00:00Z

Two of these differences include the origin of the mouth opening and the way in which the coelom is formed. Concepts of Biology 2013-04-25T00:00:00Z

The organs of the coelom are supported by the aqueous fluid, which also resists external compression. Biology for AP Courses 2022-06-09T00:00:00Z

The former, to which they limited the use of the word coelom, and which is developed directly or indirectly from the enteron, is found in Annelida, Arthropoda, Echinodermata, Chordata, &c. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z

Into the space between the walls of the coelom and the outer body-wall, originally filled with jelly, definite cells now wandered, chiefly derived from the coelomic walls. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 10 "Echinoderma" to "Edward" 2011-01-19T03:00:19.027Z

Organs housed within the coelom can grow and move freely, which promotes optimal organ development and placement. Fundamentals of Biology 2015-01-01T00:00:00Z

Using the following terms, explain what classifications and groups humans fall into, from the most general to the most specific: symmetry, germ layers, coelom, embryological development. Concepts of Biology 2013-04-25T00:00:00Z

Movement in a hydrostatic skeleton is provided by muscles that surround the coelom. Biology for AP Courses 2022-06-09T00:00:00Z

It is generally, though not always, developed from the endoderm, either as hollow outgrowths containing prolongations of the enteric cavity, which become the coelom, or as solid proliferations. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z

I, II, III, coelom of the first, second and third somites. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 6 "Armour Plates" to "Arundel, Earls of"

The coelom also provides space for the diffusion of gases and nutrients, as well as body flexibility, promoting improved animal motility. Fundamentals of Biology 2015-01-01T00:00:00Z

Annelids have a true coelom in which organs are distributed and bathed in coelomic fluid. Concepts of Biology 2013-04-25T00:00:00Z

The muscles in a hydrostatic skeleton contract to change the shape of the coelom; the pressure of the fluid in the coelom produces movement. Biology for AP Courses 2022-06-09T00:00:00Z

In Arthropoda the origin of the coelom is similar to that of Annelids, but its history is not completely known in any group, with the exception of Peripatus. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z

They contain the same fluid as the general coelom. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 3 "Borgia, Lucrezia" to "Bradford, John"

This membrane also lines the organs within the coelom, connecting and holding them in position while allowing them some free motion. Fundamentals of Biology 2015-01-01T00:00:00Z

These animals have a true coelom, a portion of which is modified into a unique circulatory system called a water vascular system. Concepts of Biology 2013-04-25T00:00:00Z

The two lateral lobes contain the coelom; each separates off in front a segment which forms the head and presumably then divides again to form anteriorly the trunk, and posteriorly the tail regions. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

This chamber is formed by the coelomic or peritoneal wall; the space enclosed is originally part of the coelom, and in Sepia and Loligo is, in the adult, part of the viscero-pericardial chamber. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics"

In Crania it is completely shut off from the main coelom, but in Lingula it communicates freely with this cavity. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 3 "Borgia, Lucrezia" to "Bradford, John"

A third group of triploblasts has a slightly different coelom derived partly from mesoderm and partly from endoderm, which is found between the two layers. Fundamentals of Biology 2015-01-01T00:00:00Z

Animals with three germ layers, called triploblasts, are further characterized by the presence or absence of an internal body cavity called a coelom. Concepts of Biology 2013-04-25T00:00:00Z

In another sense also the coelom is not a closed cavity, for it communicates in several ways with the external medium. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The gonad develops from the wall of the coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics"

Some of the endothelial cells lining the coelom are ciliated, the cilia keeping the corpusculated fluid contents in movement. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 3 "Borgia, Lucrezia" to "Bradford, John"

The coelom is divided into two symmetrical parts that are separated by two spokes of mesoderm. Fundamentals of Biology 2015-01-01T00:00:00Z

Eucoelomates have a body cavity within the mesoderm, called a coelom, which is lined with mesoderm tissue. Concepts of Biology 2013-04-25T00:00:00Z

It is remarkable, in view of the spaciousness of the coelom, that the funnels of the latter have not been seen. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

After the pericardium and pleurae have been separated off the remainder of the coelom becomes the peritoneum. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 6 "Cockaigne" to "Columbus, Christopher"

The chief difference is that the gonad or generative portion of the coelom is single and median, opening into the pericardium by a single posterior aperture. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 2 "Chicago, University of" to "Chiton"

In protostomes, two circular layers of mesoderm form inside the gastrula, containing the coelom cavity. Fundamentals of Biology 2015-01-01T00:00:00Z

Of these divisions of the coelom the first two communicate with the exterior by means of a pair of ciliated pore-canals placed at the posterior end of their respective segments. Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy"

Furthermore, in the mid region of the body this coelom is broken up by metamerically arranged septa, as in Acanthobdella. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

In the intestinal region the coelom is only present on the left side. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 6 "Cockaigne" to "Columbus, Christopher"

Demonstrate in a dog-fish the pathetic nerve, the opening between pericardium and coelom. the abdominal pores, and the ureter. Text Book of Biology, Part 1: Vertebrata

These pouches eventually fuse to form the mesoderm, which then gives rise to the coelom. Fundamentals of Biology 2015-01-01T00:00:00Z

In the direct development Bateson showed that the three divisions of the coelom arise as pouches constricted off from the archenteron or primitive gut, thus resembling the development of the mesoblastic somites of Amphioxus. Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy"

Here also the blood system has no communication with the sinus system of the coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The coelom theory brought some light and order into this infinite confusion by establishing the following points: 1. The Evolution of Man — Volume 1

The coelom of the dog-fish is peculiar-- among the types we treat of-- in the possession of two direct communications with the exterior, in addition to the customary indirect way through the oviduct. Text Book of Biology, Part 1: Vertebrata

One such structure that is used in classification of animals is the coelom. Fundamentals of Biology 2015-01-01T00:00:00Z

Many more instances of organs, of which the beginning and end have been cut off, might be mentioned; e.g. the muscle-plate coelom of Aves, the primitive streak and the neurenteric canal of amniote blastoderms. Darwin and Modern Science

These tubes are lined by flattened epithelium and often contain blood capillaries; they communicate with the coelom and are to be regarded as prolongation of it into the thickness of the body wall. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The many new points of view and fresh ideas suggested by my gastraea theory and Hertwig's coelom theory led to the publication of a number of writings on the theory of germinal layers. The Evolution of Man — Volume 1

A true coelom arises entirely within the mesoderm germ layer and is lined by an epithelial membrane. Fundamentals of Biology 2015-01-01T00:00:00Z

A coelom is a body cavity that forms during early embryonic development. Fundamentals of Biology 2015-01-01T00:00:00Z

The coelom of most protostomes is formed through a process called schizocoely, meaning that during development, a solid mass of the mesoderm splits apart and forms the hollow opening of the coelom. Fundamentals of Biology 2015-01-01T00:00:00Z

Gonads and Gonad Ducts.—The gonads and their ducts in the Hirudinea invariably form a closed system of cavities entirely shut off from the coelom in which they lie. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Simple animals, such as worms and jellyfish, do not have a coelom. Fundamentals of Biology 2015-01-01T00:00:00Z

These animals are thought to have evolved from coelomates and may have lost their ability to form a coelom through genetic mutations. Fundamentals of Biology 2015-01-01T00:00:00Z

The coelom allows for compartmentalization of the body parts, so that different organ systems can evolve and nutrient transport is possible. Fundamentals of Biology 2015-01-01T00:00:00Z

Thus, this step in early embryogenesis—the formation of the coelom—has had a large evolutionary impact on the various species of the animal kingdom. Fundamentals of Biology 2015-01-01T00:00:00Z

On the other hand, it has been held that in these leeches there is no vascular system at all and that the entire system of spaces is coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

There are a series of other developmental characteristics that differ between protostomes and deuterostomes, including the mode of formation of the coelom and the early cell division of the embryo. Fundamentals of Biology 2015-01-01T00:00:00Z

Finally, there are certain Polychaeta, e g. the Capitellidae, in which the vascular system has vanished altogether, leaving a coelom containing haemoglobin-impregnated corpuscles. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Additionally, because the coelom is a fluid-filled cavity, it protects the organs from shock and compression. Fundamentals of Biology 2015-01-01T00:00:00Z

Chaetopoda are characterized by a spacious coelom, which is divided into a series of chambers in accordance with the general metamerism of the body. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The body wall of the Chaetopoda consists of a “dermo-muscular” tube which is separated from the gut by the coelom and its peritoneal walls, except in most leeches. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

It has been held that the condition shown in certain leeches tend to prove that the coelom and haemocoel are primitively one series of spaces which have been gradually differentiated. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Nephridia.—The nephridia in this group are invariably coiled tubes with an intracellular lumen and nearly invariably open into the coelom by a funnel. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

All vertebrates have a coelom that helped them evolve complex organ systems. Fundamentals of Biology 2015-01-01T00:00:00Z

Its cavity also is at first independent of the coelom though later invaded by the latter. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The ganglia are crowded at the posterior end of the body as in leeches, and there is much tendency to the obliteration of the coelom as in that group. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

In these and other Chaetopods the coelom is also put into indirect relations with the outside world by the nephridia and by the gonad ducts. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Vascular System.—In addition to the coelom, another system of fluid-holding spaces lies between the body wall and the gut in the Chaetopoda. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The development of a closed circulatory system derived from the coelom is a significant difference seen in this species compared to other pseudocoelomate phyla. Fundamentals of Biology 2015-01-01T00:00:00Z

Nerve cord lies in coelom; brain in first segment or prostomium in many forms. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

These regions of the coelom end at the ends of the body and communicate with each other by means of a branched system of coelomic sinuses, which are in places very fine tubes. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Carry the process but a little farther and the coelom disappears and its place is taken by a blood space or haemocoel. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

In this worm the ventral blood-vessel is so swollen as to occupy nearly the whole of the available coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Annelids show the presence of a true coelom, derived from embryonic mesoderm and protostomy. Fundamentals of Biology 2015-01-01T00:00:00Z

In both the cavity originally or immediately continuous with the coelom appears first in the funnel and grows backwards. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Neither in this genus nor in the last is there any communication between coelom and vascular system. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Coelom.—The coelom of the Hirudinea differs in most genera from that of the Oligochaeta and Polychaeta. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The coelom is lined throughout by cells, which upon the intestine become large and loaded with excretory granules, and are known as chloragogen cells. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

In some animals, such as mammals, the part of the coelom called the pleural cavity provides space for the lungs to expand during breathing. Fundamentals of Biology 2015-01-01T00:00:00Z

Several forms of cells float freely in the fluid of the coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

This state of affairs has no antecedent improbability about it, since in the Vertebrata the coelom is unquestionably confluent with the haemal system through the lymphatic vessels. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Among the simpler Chaetopoda the coelom retains the character of a series of paired chambers, showing the above relations to the exterior and to the gonads. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The division and, indeed, partial suppression of the coelom culminates in the leeches, which in this, as in some other respects, are the most modified of Annelids. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The evolution of the coelom is associated with many functional advantages. Fundamentals of Biology 2015-01-01T00:00:00Z

With a few exceptions among the Polychaeta the vascular system is always present among the Chaetopoda, and always consists of a system of vessels with definite walls, which rarely communicate with the coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

The cavity of the former has nothing to do with coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

It has been indeed largely upon the conditions characterizing the Chaetopoda that the conception of the coelom in the Coelomocoela has been based. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

To this pericardial coelom is frequently added a gonocoel enclosing the gonads and the funnels of their ducts. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Primarily, the coelom provides cushioning and shock absorption for the major organ systems. Fundamentals of Biology 2015-01-01T00:00:00Z

In others, it lies in the coelom, often surrounded by a special and occasionally rather thick sheath. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

In the Oligochaeta there is a closer correspondence between external metamerism and the divisions of the coelom than is apparent in some Chaetopods. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

Both series of organs consist essentially of a ciliated tube leading from the coelom to the exterior. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

This coelom is lined by peritoneal cells and is divided into a series of metameres by septa which correspond to the segmentation of the body, the arrangement being thus precisely like that of typical Chaetopoda. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"

单词	coelom
例句	coelom This layer multiplies into a band and then splits internally to form the coelom; this protostomic coelom is hence termed schizocoelom. Fundamentals of Biology 2015-01-01T00:00:00Z A true coelom arises entirely within the mesoderm germ layer. Concepts of Biology 2013-04-25T00:00:00Z Beating cilia at the opening of the nephridium draw water from the coelom into a tubule. Biology for AP Courses 2022-06-09T00:00:00Z Most complex animals have a body cavity, or coelom. Miller & Levine Biology 2018-01-01T00:00:00Z The kidney duct is seen running along the roof of the coelom on either side. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8 "Cube" to "Daguerre, Louis" 2012-01-31T03:00:17.257Z These animals possess a true coelom that is modified into a unique circulatory system called a water vascular system. Fundamentals of Biology 2015-01-01T00:00:00Z Other developmental characteristics differ between protostomes and deuterostomes, including the mode of formation of the coelom and the early cell division of the embryo. Concepts of Biology 2013-04-25T00:00:00Z These organisms produce sperm and eggs from undifferentiated cells in their coelom and store them in that cavity. Biology for AP Courses 2022-06-09T00:00:00Z Development shows that the glandular tube is mesoblastic in origin and is of the nature of a coelomoduct, while the end-sac is to be regarded as a vestigial portion of the coelom. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z When the pus escapes from the tubes into the coelom it sets up pelvic peritonitis. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" 2011-12-26T03:00:11.613Z The presence of a coelom affords many advantages, and animals with a coelom may be termed true coelomates or pseudocoelomates, depending on which tissue gives rise to the coelom. Fundamentals of Biology 2015-01-01T00:00:00Z Two of these differences include the origin of the mouth opening and the way in which the coelom is formed. Concepts of Biology 2013-04-25T00:00:00Z The organs of the coelom are supported by the aqueous fluid, which also resists external compression. Biology for AP Courses 2022-06-09T00:00:00Z The former, to which they limited the use of the word coelom, and which is developed directly or indirectly from the enteron, is found in Annelida, Arthropoda, Echinodermata, Chordata, &c. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z Into the space between the walls of the coelom and the outer body-wall, originally filled with jelly, definite cells now wandered, chiefly derived from the coelomic walls. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 10 "Echinoderma" to "Edward" 2011-01-19T03:00:19.027Z Organs housed within the coelom can grow and move freely, which promotes optimal organ development and placement. Fundamentals of Biology 2015-01-01T00:00:00Z Using the following terms, explain what classifications and groups humans fall into, from the most general to the most specific: symmetry, germ layers, coelom, embryological development. Concepts of Biology 2013-04-25T00:00:00Z Movement in a hydrostatic skeleton is provided by muscles that surround the coelom. Biology for AP Courses 2022-06-09T00:00:00Z It is generally, though not always, developed from the endoderm, either as hollow outgrowths containing prolongations of the enteric cavity, which become the coelom, or as solid proliferations. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z I, II, III, coelom of the first, second and third somites. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 6 "Armour Plates" to "Arundel, Earls of" The coelom also provides space for the diffusion of gases and nutrients, as well as body flexibility, promoting improved animal motility. Fundamentals of Biology 2015-01-01T00:00:00Z Annelids have a true coelom in which organs are distributed and bathed in coelomic fluid. Concepts of Biology 2013-04-25T00:00:00Z The muscles in a hydrostatic skeleton contract to change the shape of the coelom; the pressure of the fluid in the coelom produces movement. Biology for AP Courses 2022-06-09T00:00:00Z In Arthropoda the origin of the coelom is similar to that of Annelids, but its history is not completely known in any group, with the exception of Peripatus. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z They contain the same fluid as the general coelom. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 3 "Borgia, Lucrezia" to "Bradford, John" This membrane also lines the organs within the coelom, connecting and holding them in position while allowing them some free motion. Fundamentals of Biology 2015-01-01T00:00:00Z These animals have a true coelom, a portion of which is modified into a unique circulatory system called a water vascular system. Concepts of Biology 2013-04-25T00:00:00Z The two lateral lobes contain the coelom; each separates off in front a segment which forms the head and presumably then divides again to form anteriorly the trunk, and posteriorly the tail regions. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" This chamber is formed by the coelomic or peritoneal wall; the space enclosed is originally part of the coelom, and in Sepia and Loligo is, in the adult, part of the viscero-pericardial chamber. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" In Crania it is completely shut off from the main coelom, but in Lingula it communicates freely with this cavity. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 3 "Borgia, Lucrezia" to "Bradford, John" A third group of triploblasts has a slightly different coelom derived partly from mesoderm and partly from endoderm, which is found between the two layers. Fundamentals of Biology 2015-01-01T00:00:00Z Animals with three germ layers, called triploblasts, are further characterized by the presence or absence of an internal body cavity called a coelom. Concepts of Biology 2013-04-25T00:00:00Z In another sense also the coelom is not a closed cavity, for it communicates in several ways with the external medium. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The gonad develops from the wall of the coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" Some of the endothelial cells lining the coelom are ciliated, the cilia keeping the corpusculated fluid contents in movement. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 3 "Borgia, Lucrezia" to "Bradford, John" The coelom is divided into two symmetrical parts that are separated by two spokes of mesoderm. Fundamentals of Biology 2015-01-01T00:00:00Z Eucoelomates have a body cavity within the mesoderm, called a coelom, which is lined with mesoderm tissue. Concepts of Biology 2013-04-25T00:00:00Z It is remarkable, in view of the spaciousness of the coelom, that the funnels of the latter have not been seen. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" After the pericardium and pleurae have been separated off the remainder of the coelom becomes the peritoneum. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 6 "Cockaigne" to "Columbus, Christopher" The chief difference is that the gonad or generative portion of the coelom is single and median, opening into the pericardium by a single posterior aperture. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 2 "Chicago, University of" to "Chiton" In protostomes, two circular layers of mesoderm form inside the gastrula, containing the coelom cavity. Fundamentals of Biology 2015-01-01T00:00:00Z Of these divisions of the coelom the first two communicate with the exterior by means of a pair of ciliated pore-canals placed at the posterior end of their respective segments. Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Furthermore, in the mid region of the body this coelom is broken up by metamerically arranged septa, as in Acanthobdella. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" In the intestinal region the coelom is only present on the left side. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 6 "Cockaigne" to "Columbus, Christopher" Demonstrate in a dog-fish the pathetic nerve, the opening between pericardium and coelom. the abdominal pores, and the ureter. Text Book of Biology, Part 1: Vertebrata These pouches eventually fuse to form the mesoderm, which then gives rise to the coelom. Fundamentals of Biology 2015-01-01T00:00:00Z In the direct development Bateson showed that the three divisions of the coelom arise as pouches constricted off from the archenteron or primitive gut, thus resembling the development of the mesoblastic somites of Amphioxus. Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Here also the blood system has no communication with the sinus system of the coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The coelom theory brought some light and order into this infinite confusion by establishing the following points: 1. The Evolution of Man — Volume 1 The coelom of the dog-fish is peculiar-- among the types we treat of-- in the possession of two direct communications with the exterior, in addition to the customary indirect way through the oviduct. Text Book of Biology, Part 1: Vertebrata One such structure that is used in classification of animals is the coelom. Fundamentals of Biology 2015-01-01T00:00:00Z Many more instances of organs, of which the beginning and end have been cut off, might be mentioned; e.g. the muscle-plate coelom of Aves, the primitive streak and the neurenteric canal of amniote blastoderms. Darwin and Modern Science These tubes are lined by flattened epithelium and often contain blood capillaries; they communicate with the coelom and are to be regarded as prolongation of it into the thickness of the body wall. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The many new points of view and fresh ideas suggested by my gastraea theory and Hertwig's coelom theory led to the publication of a number of writings on the theory of germinal layers. The Evolution of Man — Volume 1 A true coelom arises entirely within the mesoderm germ layer and is lined by an epithelial membrane. Fundamentals of Biology 2015-01-01T00:00:00Z A coelom is a body cavity that forms during early embryonic development. Fundamentals of Biology 2015-01-01T00:00:00Z The coelom of most protostomes is formed through a process called schizocoely, meaning that during development, a solid mass of the mesoderm splits apart and forms the hollow opening of the coelom. Fundamentals of Biology 2015-01-01T00:00:00Z Gonads and Gonad Ducts.—The gonads and their ducts in the Hirudinea invariably form a closed system of cavities entirely shut off from the coelom in which they lie. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Simple animals, such as worms and jellyfish, do not have a coelom. Fundamentals of Biology 2015-01-01T00:00:00Z These animals are thought to have evolved from coelomates and may have lost their ability to form a coelom through genetic mutations. Fundamentals of Biology 2015-01-01T00:00:00Z The coelom allows for compartmentalization of the body parts, so that different organ systems can evolve and nutrient transport is possible. Fundamentals of Biology 2015-01-01T00:00:00Z Thus, this step in early embryogenesis—the formation of the coelom—has had a large evolutionary impact on the various species of the animal kingdom. Fundamentals of Biology 2015-01-01T00:00:00Z On the other hand, it has been held that in these leeches there is no vascular system at all and that the entire system of spaces is coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" There are a series of other developmental characteristics that differ between protostomes and deuterostomes, including the mode of formation of the coelom and the early cell division of the embryo. Fundamentals of Biology 2015-01-01T00:00:00Z Finally, there are certain Polychaeta, e g. the Capitellidae, in which the vascular system has vanished altogether, leaving a coelom containing haemoglobin-impregnated corpuscles. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Additionally, because the coelom is a fluid-filled cavity, it protects the organs from shock and compression. Fundamentals of Biology 2015-01-01T00:00:00Z Chaetopoda are characterized by a spacious coelom, which is divided into a series of chambers in accordance with the general metamerism of the body. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The body wall of the Chaetopoda consists of a “dermo-muscular” tube which is separated from the gut by the coelom and its peritoneal walls, except in most leeches. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" It has been held that the condition shown in certain leeches tend to prove that the coelom and haemocoel are primitively one series of spaces which have been gradually differentiated. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Nephridia.—The nephridia in this group are invariably coiled tubes with an intracellular lumen and nearly invariably open into the coelom by a funnel. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" All vertebrates have a coelom that helped them evolve complex organ systems. Fundamentals of Biology 2015-01-01T00:00:00Z Its cavity also is at first independent of the coelom though later invaded by the latter. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The ganglia are crowded at the posterior end of the body as in leeches, and there is much tendency to the obliteration of the coelom as in that group. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" In these and other Chaetopods the coelom is also put into indirect relations with the outside world by the nephridia and by the gonad ducts. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Vascular System.—In addition to the coelom, another system of fluid-holding spaces lies between the body wall and the gut in the Chaetopoda. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The development of a closed circulatory system derived from the coelom is a significant difference seen in this species compared to other pseudocoelomate phyla. Fundamentals of Biology 2015-01-01T00:00:00Z Nerve cord lies in coelom; brain in first segment or prostomium in many forms. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" These regions of the coelom end at the ends of the body and communicate with each other by means of a branched system of coelomic sinuses, which are in places very fine tubes. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Carry the process but a little farther and the coelom disappears and its place is taken by a blood space or haemocoel. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" In this worm the ventral blood-vessel is so swollen as to occupy nearly the whole of the available coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Annelids show the presence of a true coelom, derived from embryonic mesoderm and protostomy. Fundamentals of Biology 2015-01-01T00:00:00Z In both the cavity originally or immediately continuous with the coelom appears first in the funnel and grows backwards. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Neither in this genus nor in the last is there any communication between coelom and vascular system. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Coelom.—The coelom of the Hirudinea differs in most genera from that of the Oligochaeta and Polychaeta. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The coelom is lined throughout by cells, which upon the intestine become large and loaded with excretory granules, and are known as chloragogen cells. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" In some animals, such as mammals, the part of the coelom called the pleural cavity provides space for the lungs to expand during breathing. Fundamentals of Biology 2015-01-01T00:00:00Z Several forms of cells float freely in the fluid of the coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" This state of affairs has no antecedent improbability about it, since in the Vertebrata the coelom is unquestionably confluent with the haemal system through the lymphatic vessels. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Among the simpler Chaetopoda the coelom retains the character of a series of paired chambers, showing the above relations to the exterior and to the gonads. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The division and, indeed, partial suppression of the coelom culminates in the leeches, which in this, as in some other respects, are the most modified of Annelids. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The evolution of the coelom is associated with many functional advantages. Fundamentals of Biology 2015-01-01T00:00:00Z With a few exceptions among the Polychaeta the vascular system is always present among the Chaetopoda, and always consists of a system of vessels with definite walls, which rarely communicate with the coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The cavity of the former has nothing to do with coelom. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" It has been indeed largely upon the conditions characterizing the Chaetopoda that the conception of the coelom in the Coelomocoela has been based. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" To this pericardial coelom is frequently added a gonocoel enclosing the gonads and the funnels of their ducts. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Primarily, the coelom provides cushioning and shock absorption for the major organ systems. Fundamentals of Biology 2015-01-01T00:00:00Z In others, it lies in the coelom, often surrounded by a special and occasionally rather thick sheath. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" In the Oligochaeta there is a closer correspondence between external metamerism and the divisions of the coelom than is apparent in some Chaetopods. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" Both series of organs consist essentially of a ciliated tube leading from the coelom to the exterior. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" This coelom is lined by peritoneal cells and is divided into a series of metameres by septa which correspond to the segmentation of the body, the arrangement being thus precisely like that of typical Chaetopoda. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross"
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