| 单词 | ectoderm |
| 例句 | In an unexpected twist, no part of the sea star ectoderm expresses a "trunk" genetic patterning program, suggesting that sea stars are mostly headlike. Where is a sea star's head? Maybe just about everywhere 2023-11-01T04:00:00Z After gastrulation, the embryo can be thought of as an onion with three layers: the ectoderm, the mesoderm and the endoderm. Career choice in stem cells: Predetermined or self-selected? 2023-09-19T04:00:00Z Sandwiched between the endoderm and the ectoderm is a non-living layer. Fundamentals of Biology 2015-01-01T00:00:00Z The ectoderm gives rise to the nervous system and the epidermis, among other tissues. Concepts of Biology 2013-04-25T00:00:00Z These disks eventually formed the three main cell layers of the body: the endoderm, mesoderm and ectoderm. Lab-Grown Monkey Embryos Reveal in 3-D How Organs Begin 2023-05-15T04:00:00Z The three germs layers, shown in Figure 34.23, are the endoderm, the ectoderm, and the mesoderm. Biology for AP Courses 2022-06-09T00:00:00Z Embryonic animal cells differentiate into three germ layers—endoderm, mesoderm, and ectoderm—each developing into different organs and systems. Miller & Levine Biology 2018-01-01T00:00:00Z The inner layer is the endoderm, and the outer layer is the ectoderm. Fundamentals of Biology 2015-01-01T00:00:00Z Triploblasts develop a third layer—the mesoderm—between the endoderm and ectoderm. Concepts of Biology 2013-04-25T00:00:00Z Within the first 8 weeks of gestation, a developing embryo establishes the rudimentary structures of all of its organs and tissues from the ectoderm, mesoderm, and endoderm. Anatomy and Physiology 2013-06-19T00:00:00Z The ectoderm gives rise to the nervous system and the epidermis. Biology for AP Courses 2022-06-09T00:00:00Z Animals with radial symmetry only have the endoderm and ectoderm. Miller & Levine Biology 2018-01-01T00:00:00Z The ectoderm develops into the outer epithelial covering of the body surface, the central nervous system, and a few other structures. Fundamentals of Biology 2015-01-01T00:00:00Z The animal phyla of this and subsequent modules are triploblastic and have an embryonic mesoderm sandwiched between the ectoderm and endoderm. Concepts of Biology 2013-04-25T00:00:00Z Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. Anatomy and Physiology 2013-06-19T00:00:00Z For example, some cells in the ectoderm will express the genes specific to skin cells. Biology for AP Courses 2022-06-09T00:00:00Z For instance, the gut tube and liver derive from the endoderm; muscle and connective tissue from the mesoderm; and neural tissue and skin from the ectoderm. A decade of questions about the fluidity of cell identity 2020-02-23T05:00:00Z The mesoderm is the third germ layer; it forms between the endoderm and ectoderm in triploblasts. Fundamentals of Biology 2015-01-01T00:00:00Z The dorsal hollow nerve cord is derived from ectoderm that sinks below the surface of the skin and rolls into a hollow tube during development. Concepts of Biology 2013-04-25T00:00:00Z As the embryo develops, a portion of the ectoderm differentiates into a specialized region of neuroectoderm, which is the precursor for the tissue of the nervous system. Anatomy and Physiology 2013-06-19T00:00:00Z The ectoderm forms epithelial cells and tissues, and neuronal tissues. Biology for AP Courses 2022-06-09T00:00:00Z In gastrulation, the epiblast differentiates into the three germ layers of cells — the ectoderm, mesoderm and endoderm — that will form the fetus. Human embryo implantation modelled in microfluidic channels 2019-09-10T04:00:00Z 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 The three germ layers are the endoderm, the ectoderm, and the mesoderm. Concepts of Biology 2013-04-25T00:00:00Z All cells and tissues in the body derive from three germ layers in the embryo: the ectoderm, mesoderm, and endoderm. Anatomy and Physiology 2013-06-19T00:00:00Z During the formation of the neural system, special signaling molecules called growth factors signal some cells at the edge of the ectoderm to become epidermis cells. Biology for AP Courses 2022-06-09T00:00:00Z Complementing these previous studies, our results suggest that it may play a central role in mediating the transition from pluripotency to early ectoderm. Transcription factor binding dynamics during human ES cell differentiation : Nature : Nature Publishing Group 2015-02-17T05:00:00Z Outside this digestive cavity are three tissue layers: an inner endoderm, a central mesoderm, and an outer ectoderm. Fundamentals of Biology 2015-01-01T00:00:00Z This tube will eventually become the brain and spinal cord, while the rest of the ectoderm goes on to form skin. The man who grew eyes 2014-08-26T04:00:00Z Note that epithelial tissue originates in all three layers, whereas nervous tissue derives primarily from the ectoderm and muscle tissue from mesoderm. Anatomy and Physiology 2013-06-19T00:00:00Z If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue. Biology for AP Courses 2022-06-09T00:00:00Z Complementing these previous studies, our results suggest that it may play a central role in mediating the transition from pluripotency to early ectoderm. Transcription factor binding dynamics during human ES cell differentiation : Nature : Nature Publishing Group 2015-02-17T05:00:00Z 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 After several days of growth in the suspended culture, Sasai’s ectoderm cells spontaneously change shape. The man who grew eyes 2014-08-26T04:00:00Z The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. Anatomy and Physiology 2013-06-19T00:00:00Z Figure 34.25 The central region of the ectoderm forms the neural tube, which gives rise to the brain and the spinal cord. Biology for AP Courses 2022-06-09T00:00:00Z We maintained the cells for three days in feeder-free culture and then induced directed differentiation towards mesendoderm, endoderm, mesoderm, and ectoderm using different media conditions. Transcription factor binding dynamics during human ES cell differentiation : Nature : Nature Publishing Group 2015-02-17T05:00:00Z Both are derived from ectoderm, the outer layer of cells in an embryo. Psychodermatology: An emotional response 2012-12-19T18:21:00.890Z Sasai’s lab-grown pituitaries form from interactions between tissues from two distinct regions of the embryo; their meeting causes part of the ectoderm to fold in on itself and detach, making a small pouch. The man who grew eyes 2014-08-26T04:00:00Z As the neural folds come together and converge, the underlying structure forms into a tube just beneath the ectoderm called the neural tube. Anatomy and Physiology 2013-06-19T00:00:00Z The endoderm, mesoderm, and ectoderm are germ layers. Biology for AP Courses 2022-06-09T00:00:00Z We stopped at each house, allowing our paying customers to rub the ectoderm and work the stem, choosing the one they wanted. Opinion: The Pumpkin Cartel of Corning, N.Y. 2012-10-13T23:27:01Z S, serosa; A, amnion; E, ectoderm; N, rudiment of nerve-cord; M, mesodermal pouches. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 4 "Hero" to "Hindu Chronology" 2012-04-04T02:00:56.447Z During embryonic development, all the body's organs and tissues develop from one of the three germ layers: endoderm, mesoderm and ectoderm. Stem Cells: Flexible friends 2012-02-29T18:21:27.080Z Cells from the neural folds then separate from the ectoderm to form a cluster of cells referred to as the neural crest, which runs lateral to the neural tube. Anatomy and Physiology 2013-06-19T00:00:00Z How do the ectoderm cells determine which type of cells to form? Biology for AP Courses 2022-06-09T00:00:00Z The rudiment of the central nervous system has the form of a solid keel-like ingrowth of ectoderm along the mid-dorsal line, which only secondarily becomes hollowed out—just as happens in Teleostean fishes. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 8 "Cube" to "Daguerre, Louis" 2012-01-31T03:00:17.257Z The micromeres give rise to the ectoderm; each of the sixteen macromeres, after budding off a small mesoblast cell, passes on as endoderm. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" 2012-01-22T03:00:24.397Z Evidently then this ectoderm or outer layer is of the very greatest importance in embryology, since from it arise all those parts of the embryo itself which are the most important in its future life. Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z As the two sides of the neural groove converge, they form the neural tube, which lies beneath the ectoderm. Anatomy and Physiology 2013-06-19T00:00:00Z The mesoderm, located at the border of the neural plate and the non-neural ectoderm, develops into various connective tissues such as the facial cartilage, ribs, and lungs. Biology for AP Courses 2022-06-09T00:00:00Z Farther up, within the velar area, the rudiments of the cerebral nerve-ganglion ng are seen separating from the ectoderm. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5 "Gassendi, Pierre" to "Geocentric" 2011-09-02T02:00:20.450Z These layers are severally called ectoderm and endoderm. Marvels of Pond-life A Year's Microscopic Recreations 2011-08-01T02:00:12.067Z This cavity is termed by embryologists the “amniotic cavity,” and the cells which line it, and which in their turn become arranged as a separate layer, form what is termed the “embryonic ectoderm.” Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z As the neural tube separates from the rest of the ectoderm, the side closest to the surface is dorsal, and the deeper side is ventral. Anatomy and Physiology 2013-06-19T00:00:00Z The cells of the ectoderm are not homogeneous. Freshwater Sponges, Hydroids & Polyzoa 2011-06-25T02:00:17.833Z 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 lens of the lateral eye of the vertebrates is derived by an invagination of the ectoderm, which meets and fits in the retinal cup at the end of the optic vesicle. Degeneracy Its Causes, Signs and Results 2011-05-02T02:00:17.657Z The shading is due to an increased growth of cells, because here the three germinal layers—embryonic ectoderm, mesoderm, and entoderm—are in contact. Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z The outer layer of the embryo, the ectoderm, gives rise to the skin and the nervous system. Anatomy and Physiology 2013-06-19T00:00:00Z Adhesion between the tentacles and the prey is effected partly by the gummy secretion of the glands of the ectoderm, which is perhaps poisonous as well as adhesive, and partly by the threads. Freshwater Sponges, Hydroids & Polyzoa 2011-06-25T02:00:17.833Z Finally, in certain Echinodermata the ventral part of the central nervous system arises by the invagination of a linear streak of ectoderm, the cavity of the invagination persisting as the epineural canal. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z In the typical invertebrate eye, on the contrary, the retinal cells are differentiated from the external ectoderm. Degeneracy Its Causes, Signs and Results 2011-05-02T02:00:17.657Z Amongst other structures which arise from the important layer of ectoderm are the teeth. Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z The pineal gland also arises from the ectoderm. Anatomy and Physiology 2013-06-19T00:00:00Z The embryo is held in position partly by means of the cup of elongated ectoderm cells and partly by a delicate film of mucus secreted by the parent. Freshwater Sponges, Hydroids & Polyzoa 2011-06-25T02:00:17.833Z Huxley, who compared the serous and mucous layers of Pander with the ectoderm and endoderm of the Coelenterata. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z Identify the endoderm and ectoderm cells, the spicules or fibers, and, among the spicules or fibers, irregular amœboid cells, sometimes called mesoderm cells. A Guide for the Study of Animals 2011-01-18T03:00:14.913Z These layers we saw were termed the germinal layers, and were named respectively the “ectoderm,” the “entoderm,” and the “mesoderm”—the last appearing between the two former. Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z In contrast, endocrine glands that arise from the endoderm and ectoderm produce the amine, peptide, and protein hormones. Anatomy and Physiology 2013-06-19T00:00:00Z The egg of Hydra is said to be fertilized as it lies at the base of the ectoderm, through which the fertilizing spermatozoon bores its way. Freshwater Sponges, Hydroids & Polyzoa 2011-06-25T02:00:17.833Z This in almost all animals develops from the ectoderm. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The external layer, or ectoderm, is made up of cells, and contains also muscular and nervous elements. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" Then the ectoderm on the surface over the cup begins to thicken, grows into the cup itself, and ultimately forms a rounded hollow mass which we afterwards recognise as the lens of the eye. Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z The two structures of the adrenal glands arise from two different germ layers: the adrenal cortex from the mesoderm and the adrenal medulla from ectoderm neural cells. Anatomy and Physiology 2013-06-19T00:00:00Z It then makes its way by amœboid movements between the cells of the ectoderm until it reaches the surface. Freshwater Sponges, Hydroids & Polyzoa 2011-06-25T02:00:17.833Z 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 In the course of development, however, cells from the ectoderm and endoderm may migrate into it. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" The first part to appear is a portion of the inner ear, which shows itself as a round, hollowing of the ectoderm. Embryology The Beginnings of Life 2011-09-12T02:00:28.483Z The endocrine system originates from all three germ layers of the embryo, including the endoderm, ectoderm, and mesoderm. Anatomy and Physiology 2013-06-19T00:00:00Z The issuing ovum does not destroy the ectoderm cells as it passes out, but squeezes them together round the aperture it makes. Freshwater Sponges, Hydroids & Polyzoa 2011-06-25T02:00:17.833Z It arises, however, by delamination from the ectoderm, the tube being a secondary acquisition. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z It has been shown that these asulcar filaments are derived from the ectoderm, the remainder from the endoderm. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" The brain, like the rest of the nervous system, is developed from the ectoderm or outer layer of the embryo by the formation of a groove in the mid-dorsal line. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 4 "Bradford, William" to "Brequigny, Louis" Whereas the ectoderm and endoderm form tightly connected epithelial sheets, the mesodermal cells are less organized and exist as a loosely connected cell community. Anatomy and Physiology 2013-06-19T00:00:00Z The plexus of nerve-fibrils which underlie the ectoderm and are in places gathered up into nerves, and the great development of connective tissue, are worthy of notice. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 3 "Borgia, Lucrezia" to "Bradford, John" Although the central nervous system is almost always developed from the ectoderm of the embryo, the same cannot be said of the peripheral nerve trunks. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z Most commonly the spicule-forming cells pass out of the ectoderm and are imbedded in the mesogloea, where they may remain separate from one another or may be fused together to form a strong mass. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" Into these fins, which are largely cuticular and strengthened by radiating bars, a single layer of ectoderm cells projects. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The ectoderm gives rise to cell lineages that differentiate to become the central and peripheral nervous systems, sensory organs, epidermis, hair, and nails. Anatomy and Physiology 2013-06-19T00:00:00Z The otocysts and eyes are formed as invaginations of ectoderm, the former behind the eyes, at the sides of the funnel. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" 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 A ring-shaped plate of calcite, secreted by the ectoderm, is then formed, lying between the embryo and the surface of attachment. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" In addition to the eyes and the olfactory circle on the head scattered tactile papillae are found on the ectoderm. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" The Coelentera may thus be briefly defined as Metazoa which exhibit two embryonic cell-layers only,—the ectoderm and endoderm,—their body-cavities being referable to a single cavity or coelenteron in the endoderm. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 6 "Cockaigne" to "Columbus, Christopher" The mesoderm also originates at the anal side of the ectoderm and extends in two bands right and left between ectoderm and endoderm. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" Thus the ectoderm gives rise to the epidermis, to the nervous system, and to the lining of the stomodaeum and proctodaeum, if such parts of the alimentary canal are present. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The ectoderm beneath each fold becomes detached from the surface of the basal plate, and both it and the mesogloea are folded conformably with the endoderm. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" The whole of this system has retained its primitive connexion with the ectoderm. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 7 "Cerargyrite" to "Charing Cross" In the Coelentera the ectoderm and endoderm are set apart from one another at a very early period in the life-history; generally either by delamination or invagination, processes described in the article Embryology. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 6 "Cockaigne" to "Columbus, Christopher" Later on the same anal edge of the ectoderm forms another cellular layer, the endoderm proper, which forms a continuous sheet below the ectoderm. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" It is also sometimes formed from ectoderm, as in the Vertebrata at the nerve crest and other places. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z It is formed, not from fused spicules, but as a secretion of a special layer of cells derived from the basal ectoderm, and known as calicoblasts. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" The ectoderm behind the ciliated ring develops spicules, and the post-oral region of the larva elongates. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 2 "Chicago, University of" to "Chiton" The ectoderm rarely consists of more than one layer of cells: these are divisible by structure and function into nervous, muscular and secretory cells, supported by interstitial cells. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 6 "Cockaigne" to "Columbus, Christopher" The region of proliferation marks the anal side of the ectoderm, and the layer of nuclei forms the perivitelline membrane. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" As a general rule the ectoderm and endoderm, which may be called the primary layers, come first, and later the mesoderm is developed from one or other of them. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The body-wall is highly muscular and, except in a few probably specialized cases, possesses chitinous spines, the setae, which are secreted by the ectoderm and are embedded in pits of the skin. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" From the mucous layer, or endoderm, is developed the apparatus of nutrition; while from the serous layer, or ectoderm, is developed the apparatus of external action. Essays: Scientific, Political, & Speculative, Vol. I In the mollusc, on the contrary, the retina is derived from the ectoderm directly, and not indirectly by means of the embryonic encephalon. Creative Evolution All the nerve-centres, cerebral, visceral, pedal and optic, are formed as proliferations of the ectoderm. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" In it cleavage gives rise to a solid mass, which divides by delamination into two layers, the ectoderm and endoderm. 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 class out of which governmental organization originates, is, as we have said, analogous in its relations to the ectoderm of the lowest animals and of embryonic forms. Essays: Scientific, Political, & Speculative, Vol. I Now, the original lens was built out of the ectoderm, while the iris is of mesodermic origin. Creative Evolution From one part of the periphery of the ectoderm proliferation of cells takes place and gives rise to a layer of scattered nuclei over the whole surface of the yolk. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" 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 point to remember is, that in all cases a gastrula is an open sac composed of two layers of cells—the outer layer being called the ectoderm, and the inner the endoderm. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions Stomatodaeum: that invagination of the ectoderm that forms the mouth, pharynx, oesophagus, crop and gizzard. Explanation of Terms Used in Entomology 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 According to Haeckel, the origin of the generative products in the mesoderm is a heterotopic phenomenon, for he considers that they must have originated phylogenetically in one of the two primary layers, ectoderm or endoderm. Form and Function A Contribution to the History of Animal Morphology In the normal development of the tadpole from the egg, as in all other vertebrate animals, the lens is formed from the outer skin or ectoderm of the head. Biology A lecture delivered at Columbia University in the series on Science, Philosophy and Art November 20, 1907 It is enough for us that they always end in the formation of the two primary layers of ectoderm and endoderm. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions Ectoblast: the outer wall of a cell; the ectoderm or epiblast. Explanation of Terms Used in Entomology 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 To begin with the differentiation into ectoderm and endoderm, the organism is comparable to a human community made up of military and agricultural classes. The Doctrine of Evolution Its Basis and Its Scope The layer is the true outer skin—ectoderm or epidermis. The Life-Story of Insects This stage of differentiation consists in the formation of either a pouch or an additional layer between the ectoderm and the endoderm, which is called the mesoderm. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions Exochorion: that part of the chorion derived from the ectoderm: the outer layer of the chorion. Explanation of Terms Used in Entomology The one which I finally succeeded in isolating was an engaging organism with a provocative manner and a little way of wrinkling up its ectoderm which put you at once at your ease. Love Conquers All The body consists of two layers of cells, the ectoderm on the outside and the entoderm lining the digestive cavity. 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 Afterwards there are slight histological differentiations in its ectoderm, though the entoderm remains a single stratum of cells. The Evolution of Man — Volume 2 The parts lying above this axis are those which have been developed from the ectoderm and mesoderm—viz. voluntary muscles, central nervous system, and organs of special sense. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions The authors who regard this embryonic form as the primary gastrula of the placental conceive the outer layer as the ectoderm and the inner as the entoderm. The Evolution of Man — Volume 1 On the outside of the elastic membrane, just beneath the ectoderm, is a plexus or cobweb of nervous cells and fibrils. 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 Between the ectoderm and entoderm of the gastrula, in the space occupied by the supporting membrane of hydra, a new layer of cells, the mesoderm, appears. 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 We find the first differentiation of epithelial and stinging cells, or of muscular and neural cells, in the thick ectoderm of the hydra. The Evolution of Man — Volume 2 An afferent or sensory nerve-fibril, which under adequate stimulus is set in vibration by some cell of the epidermis or ectoderm, which is therefore called a sensory cell. 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 wall of the embryonic vesicle now consists throughout of two layers of cells, the ectoderm without and the entoderm within. The Evolution of Man — Volume 1 The outer envelope of dark smaller cells forms the ectoderm or skin-layer. The Evolution of Man — Volume 1 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 In these cases the simple cell-layer of the ectoderm is at once skin, locomotive apparatus, and nervous system. The Evolution of Man — Volume 2 The larger vegetal cells of the entoderm are richer in granules, and so darker than the smaller and lighter animal cells of the ectoderm. The Evolution of Man — Volume 1 In consequence of this, the animal cells of the ectoderm are darker than the vegetal cells of the entoderm. The Evolution of Man — Volume 1 These important processes of differentiation in the mesoderm, which we will consider more closely in the next chapter, proceed step by step with interesting changes in the ectoderm, while the entoderm changes little at first. The Evolution of Man — Volume 1 Also almost any part of the animal containing both ectoderm and entoderm can be cut off and will develop into a new animal. 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 cells of the entoderm are much larger, darker, and more fatty than those of the ectoderm, which are clearer and less rich in fatty particles. The Evolution of Man — Volume 2 But the globular wall of the mammal vesicle is the differentiated ectoderm, and at one point in it we find a circular disk of quite different cells—the entoderm. The Evolution of Man — Volume 1 |
| 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。