The optic cup, or its contained fluid, is one chemical compound; epithelium is another; mesoblast is a third.
Foregut: extends from the mouth to the end of gizzard; its epithelium being formed from the ectodermal invagination known as the stomodaeum.
Entoderm: the innermost germ layer of the embryo, from which are derived the epithelium of the alimentary canal and accessory structures: = endoderm and hypoblast.
The corrugated and non-epitheliated interspaces may be supposed to favour distension of the rectal chamber, while the great size of the cells of the bands of epithelium is perhaps due to their limited extent.
The epithelium of the stomodæum and proctodæum is derived, however, from two epiblastic involutions at the fore and hind ends of the embryo.
The chitinous lining and the chitinogenous layer beneath pass to the end of the tube and are then reflected upon its outer wall, ascending till they meet the lining epithelium of the cæcal tubes.
Internal to these is a basement membrane, which supports an epithelium consisting of elongate cells which are often clustered into regular eminences, and separated by deep cavities.
It is secreted by an epithelium of nucleated, chitinogenous cells, and outside this is a thin and homogeneous basement membrane.
The cells of the epithelium give rise to spermatocysts,[170] which enclose sperm cells.
Tracheal tube with its epithelium and spiral thread.
The epithelium of the mesenteron is formed out of the hypoblast, whose cells assume a cubical form and gradually absorb the yolk.
From their backward-directed prolongations arises the epithelium of the vasa deferentia and oviducts.
Basch set out with a conviction that where a chitinous lining is present, the epithelium of the alimentary canal secretes chitin only, and that proper digestive juices are only elaborated in the chylific stomach, or in the salivary glands.
The epithelium forms no chitinous lining in the chylific stomach or cæcal tubes; and this peculiarity, no doubt, promotes absorption of soluble food in this part of the alimentary canal.
In the very finest branches the tube loses its thread, the chitinogenous cells become irregular, and the intima is lost in the nucleated protoplasmic mass which replaces the regular epithelium of the wider tubes.
The epithelium of an ovarian tube presents some remarkable peculiarities which disguise its true character.
The epithelium rests upon a thin structureless basement-membrane, which is firmly united in the œsophagus and crop to the muscular layer and the epithelium.
Disturbance of the epithelium in the presence of pus without abscess usually permits enough absorption to elevate the temperature slightly for a few days.
Punctures should be made as nearly as possible perpendicular to the surface, so as to minimize the destruction of epithelium and thus lessen the reaction.
These tubes are lined by flattened epitheliumand 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.
Temporary oviducts are formed between the "sperm-duct" and the germinal epithelium at each oviposition.
Where this retina touches the epithelium the latter begins to grow into the cup, the ingrowing piece of epithelium is cut off and forms the lens, which probably under the influence of substances secreted by the optic cup becomes transparent.
The lens of the eye is formed in the embryo from the epitheliumlying above the so-called optic cup (the primitive retina).
From the endoderm come the epithelium of the respiratory tract, of most of the digestive tract with the liver and pancreas, the epithelium of the thyroid body, the bladder, and other minor parts.
Von Leyden and other German observers look upon the degenerative alteration in the epithelium of the renal tubules as pathological, but apparently more definite symptoms are necessary to make a diagnosis of significant nephritis.
The phloridzin so acts on the epithelium of the kidneys that it lets the blood-sugar escape into the urine.
It is supposed that the ovum is grasped by the fringe-like extremity of the Fallopian tube and is carried through it by the movements of the ciliary epithelium to the uterus.
Menstruation may, then, be defined as the periodic discharge of blood from the uterus, accompanied by the shedding of the epithelium of the body, as well as that of the uterine glands near their orifices.
Each renal organ is a sac lined with glandular epithelium (ciliated cell, with concretions) communicating with the exterior by its papilla, and by a narrow passage with the pericardium.
Deafness and tinnitus are dependent upon the accumulation of epithelium and débris.
At first the swelling is covered by epithelium; in time caseation takes place, the epithelium gives way, and an open sore is formed.
Microscopically the cyst was lined with squamous epithelium and the wall contained rudimentary salivary-gland tissue.
Sometimes from the admixture of a quantity of epithelium it is almost white in colour.
The oral part, which includes the anterior two-thirds of the organ, is mobile, and the epithelium on its dorsal aspect is modified so as to form several varieties of papillæ.
These tumours sometimes become cystic, the cysts being lined with ciliated epithelium and containing colloid material.
When deeply placed, they are lined by cylindrical or ciliated epithelium and contain a glairy mucoid fluid.
When near the skin they are of the nature of dermoid cysts, being lined with squamous epithelium and filled with sebaceous material.
Epithelium fragments, probably portions of the internal root-sheath, sometimes adhere to the shaft of the hair as it grows up, and look like concretions.
The hardened masses of epithelium develop in excess, the epidermal layer loses in integrity, and the surface becomes scaled like that of a fish.
The superficial layer of head ectoderm, from which the lens has been invaginated and separated, becomes the anteriorepithelium of the cornea (fig.
The healing of a corneal ulcer is characterized by the disappearance of pain where this has been a symptom and by the rounding off of its sharp margins as epithelium spreads over them from the surrounding healthy parts.
The anterior epithelium of the lens vesicle remains, but from the posterior the lens fibres are developed and these gradually fill up the cavity.
Nevertheless it is upon a minute examination of the flakes and pieces of detached epithelium that reliance must be placed.
The first step in the pathological process is probably an injury to the epithelium from abnormal or excessive fermentation, from toxic products of bacteria, or from other factors.
Defn: Epithelial mesoderm; a layer of cuboidal epithelium cells, formed from a portion of the mesoderm during the differetiation of the germ layers.
Defn: A yellow coloring matter, soluble in ether, contained in the small round fat drops in the retinal epithelium cells.
Sometimes applied to the whole layer of pigmented epithelium of the choroid.
If the down-growth of epithelium into the operative wound is permitted the effects are by no means as pronounced, and the eventual lowering of tension is not as permanent as they otherwise would be.
The scales of the cuticle or epithelium are somewhat opened, the fibre becoming slightly roughened thereby.
The epithelium of the convoluted tubules undergoes degeneration; considerable quantities of it are shed, and form the well-known casts in the urine.
Such tubules as remain are dilated, and theepithelium lining them is altered, the cells becoming hyaline and losing their structure.
A thin layer of mesoblast, probably the submucosa, sl, lies beneath the epithelium and projects up into the folds.
The epithelium consists here of three or four layers of compactly arranged cells, and has about the same appearance as in the oesophagus and duodenum.
The epithelium is here stratified instead of simple columnar, and the folds into which it is thrown are broader and less numerous than in the duodenum above described.
In the section under discussion the trachea, ta, is of about the same size as the oesophagus, but its epithelium is thicker and consists of two or three layers of cells.
On the ventral side, where the oesophageal wall is in contact with that of the trachea the epithelium is somewhat thickened by an increase in the number of cell layers.
Each bronchus, like the trachea, is lined with anepithelium of three or four layers of cells; but the epithelium is surrounded by a thin layer of much condensed mesoblast.
Its epithelium is of the simple columnar type, the cells being long, with generally basally located nuclei.
The pharyngeal epithelium is rather thicker than that of the oral cavity.
The epithelium of this part of the intestine consists of a single layer of clear, columnar cells, which, around the borders of the opening, are thrown into numerous folds and are almost of goblet form.
The epithelium of the duodenum consists of four or five layers of compactly arranged cells, near the center of an oval mass of fairly dense mesoblast.
Figure 4L, through the region of the hindgut, shows at i the completely inclosed intestine; it is a comparatively narrow tube, lined with columnar epithelium outside of which is a dense layer of mesoblast continuous with the mesentery.
The epitheliumof the stomach is fairly thick, and consists of five or six layers of compact, indistinctly outlined cells with spherical nuclei.
The inferior medullary velum, a reflection of the pia mater and epithelium from the back of the medulla to the inferior vermis, closes it in below.
This fossa is roofed over by theepithelium lining the cavity of the ventricle, by pia mater and blood-vessels constituting a choroid plexus (fig.
The lateral ventricle is lined by a ciliated epithelium called the ependyma.
It will now be seen that the original neural canal, which is lined by ciliated epithelium, forms the ventricles of the brain, while superficial to this epithelium (ependyma) the grey and white matter is subsequently formed.
Vertical section through the superficial part of an ovary of an adult Raja to shew the relation of the pseudo-epithelium to the subjacent stroma.
The colours employed are intended to render clear the distinction between the germinal epithelium (ge.
To illustrate the relation of the ovarian epithelium to the subjacent vascular stroma.
The epithelium of the alimentary canal (al) is seen closely underlying the notochord and becoming continuous with the epiblast at the hind end of the notochord.
Small portion of the deeper layer of the germinal epithelium of the same ovary as fig.
Section through a small part of the middle region of the germinalepithelium of a rabbit seven days after birth.
The follicular epithelium is much thicker on the side adjoining the stroma than on the upper side of the ovum.
Section through a small part of the innermost layer of the germinal epithelium of a rabbit seven days after birth, shewing the formation of Graafian follicles.
Muellerian duct quite free in the space between the peritoneal epithelium and the Wolffian duct, in which condition it extends until near its termination.
Small portions of the middle region of the germinal epithelium of a rabbit four weeks after birth.
Surface view of follicular epithelium from an ovum of Raja of about the same age as fig.
The figure shews the commencing differentiation of the cells of the germinal epitheliuminto true ova and follicle cells.
First or external portion of coiled tube of nephridium, lined by columnar epithelium with small nuclei; the cells project for very different distances, giving the inner boundary of this region a ragged appearance.
Small part of the follicular epithelium and egg membranes of a somewhat larger ovum of Scyllium canicula than fig.
Must be removed and pinned out immediately after death, as otherwise the epithelium will be macerated off.
Stain all sections of epithelium in picrocarmine, and in eosine and hæmatoxyline.
This membrane is the delicate wall of the capillaries and the epithelium of the air cells.
Such a simple tissue is called an epithelium or surface-limiting tissue, and the cells are known as epithelial cells.
Thus the layers of epithelium which form the superficial layer of the skin have little beyond such an office to discharge.
The glandular or spheroidalepithelium is composed of round cells or such as become angular by mutual pressure.
It shows the columnar epithelium of the surface dipping down into the duct D of the gland, from which two tubes branch off.
In the former case the epithelium is said to be simple; in the latter, stratified.
The squamous or pavement epithelium consists of very thin, flattened scales, usually with a small nucleus in the center.
This epithelium is especially common in the air passages, where it serves to keep a free passage for the entrance and exit of air.
The ciliated epithelium is marked by the presence of very fine hair-like processes called cilia, which develop from the free end of the cell and exhibit a rapid whip-like movement as long as the cell is alive.
The germinal epithelium is still semiactive and small groups of primary spermatocytes are present in nearly all of the tubules.
Although no testicular material was obtained from hibernating turtles, comparisons of sections made in October and April show that the germinal epithelium remains inactive from autumn until spring.
For, although any one individual only causes the death of a single host-cell, yet the number of the parasites may be so enormously increased by this means, that the entire affected epithelium may be overrun and destroyed.
So that, if the acute stage of the disease is once successfully passed, the regenerative capacity of the epithelium may be able to restore something like equilibrium to the deranged metabolism in time to prevent collapse.
Following from the casual method of infection, the epithelium of the gut or of its appendages (e.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "epithelium" in a variety of sentences. We hope that you will now be able to make sentences using this word.
