Lieberkuhn published in 1745 a dissertation on the villi and glands of the small intestines.
Defn: Having the villi of the placenta collected into definite patches, or cotyledons.
Defn: One of the minute papillary processes on certain vascular membranes; a villosity; as, villi cover the lining of the small intestines of many animals and serve to increase the absorbing surface.
The villiare adapted especially for the absorption of fat.
Villi are seen surrounded with the openings of the tubular glands.
It is through these villi that the digested food passes into the blood.
One of the patches of villi found in some forms of placenta.
Having the villi of the placenta collected into definite patches, or cotyledons.
From its diminutive size it may be readily overlooked, concealed or obscured by the villi among which it is suspended to the mucous membrane.
The minute granules of oil in emulsion are taken up by the epithelial cells covering the villi; thence they enter the adenoid tissue of the villi on their way to the lymphatic radicles, the lacteals.
The {272} vascular spaces into which thevilli dip become filled up and narrowed, and often disappear.
In the ileum the villi are shrunken, with few cells; in some cases they disappear altogether.
The small arteries of the villi and submucous layer, the muscular and other tissues, are infiltrated with a new material allied to fibrin.
Microscopically, it was found that the placental villiwere filled with small nucleated cells, which were especially abundant in the centre of the villous spaces along the axis where the vessels usually take their course.
The ends of the villiwere enlarged with knob-like processes.
The villi are hypertrophied, looking often like minute polypi.
These villi contain numerous capillary blood vessels and spaces known as lacteals.
Physiology teaches that the absorption of the products of digestion occurs by means of the millions of small projections or villi with which the intestinal wall is lined.
The villi seen in a mature placenta are the same as those which projected from the capsule of the young ovum, but not these alone, for many branches have sprouted from the original projections.
There is no doubt whatever that the mother's blood surrounds the placental villi but never enters the child.
The tiny lakes, in which the villi hang, are thus made a part of the mother's circulation and as such are regularly replenished with purified blood.
The interchange of material between mother and child as carried on in the placenta can, perhaps, be made clearer if we compare one of the trunks and its branching villi to a human forearm, hand, and fingers.
As the ovum sinks into this especially prepared bed, the villi are formed.
The most significant result of this restriction is, perhaps, that so long as the coating of the villi remains intact and healthful, bacteria cannot gain access to the unborn child.
It must be noticed, moreover, that the maternal blood not only brings to the surface of the villi everything the child needs, but it also takes away the waste products of fetal life.
It is able to afford such protection, because the coating of the villi is not permeable to all sorts of substances.
Villi (bow) or Villiyan (bowmen) has been recorded as a synonym of the Irulas of Chingleput.
Villi also occurs as a sub-division of Vettuvan, a hunting caste of the Tamil country.
In all these cases the area of the placental villi appears to have increased so as to cover nearly the whole subzonal membrane, without the villi increasing to any great extent in complexity.
The zonary placenta of Orycteropus is capable of being easily derived from that of Manis by the disappearance of the foetal villi at the two poles of the ovum.
The polycotyledonary forms of placenta are due to similar concentrations of the foetal villi of an originally diffused placenta.
At first the villi themselves contain no blood-vessels.
Three sets of structures are concerned in human embryonic nourishment, namely, the Allantois, the Villi of the Chorion, and the Placenta.
As they grow larger, these villi push their way into many of the small blood-vessels in the uterine wall, and so come to lie actually in a mass of blood from which they abstract the elements of nutrition.
At the end of this time most of the villi disappear, and the few that remain take part in forming the f[oe]tal or embryonic portion of the placenta.
The villi of the chorion are outgrowths by means of which the very early embryo attaches itself to the walls of the cavity, which it has made for itself in the wall of the uterus.
As we have seen, it arises partly from the villi of the chorion, which is its embryonic portion.
The nutriment supply is secretion, in the first place, of the uterine glands, which thesevilli easily absorb.
Afterwards these elements are supplied by cells which lie between the f[oe]tal villi and the blood of the mother.
Its essential character consists in the foetal villi not being uniformly distributed, but collected into patches or cotyledons which form as it were so many small placentae (fig.
The cotyledons themselves consist of a network of tissue permeated by large vascular spaces, formed by the dilatation of the maternal blood-vessels of the serotina, into which the ramifications of the foetal villi project.
The same general arrangement holds good in the diffused placentae of other forms, and in the polycotyledonary placenta of the Ruminantia, but the foetal villi (C) in the latter acquire an arborescent form.
These septa, which belong to the serotina, lie between the arborescent villi of the chorion.
In many cases peculiar processes or villi grow out from the ovum (fig.
The villi (v) are formed of a connective tissue cone with capillaries, and are covered by a layer of very flat epithelium (e) derived from the subzonal membrane.
The villi of the chorion are covered by an epithelium derived from the subzonal membrane, and are provided with a connective tissue core containing an artery and vein and a capillary plexus connecting them.
In many cases (Turner), the interlocking of the maternal and foetal structures is so close that large parts of the maternal epithelium are carried away when the foetal villi are separated from the uterus.
The layer of foetal epithelium cannot be seen on the villi of the fully-formed human placenta.
In the foetal villi the vessels retain their capillary form.
The villi are arranged in ridges which radiate from a non-villous longitudinal strip on the concave surface of the chorion.
The capillaries of the foetal villi preserve their normal size, and the villi are covered by a flat epithelial layer (e).
In these Indecidua thevilli are distributed over the whole surface of the chorion (or its greater part) either singly or in groups.
As the connective tissue between the enlarged capillaries of the uterus disappears, wide cavities filled with maternal blood appear, and into these the chorion-villi of the embryo penetrate.
They are only loosely connected with the mucous coat of the uterus, so that the whole foetal membrane with its villican be easily withdrawn from the uterine depressions like a hand from a glove.
Here again the whole surface of the chorion is thickly covered with the villi in the beginning.
As the partition in the villi between the maternal blood-vessels and those of the foetus is extremely thin, there is a direct exchange of fluid between the two, and this is of the greatest importance in the nutrition of the young mammal.
The former has only a few small villi or none at all; the latter is thickly covered with large and well-developed villi; this alone now constitutes the placenta.
A section of the Ileum, turned inside out, so as to show the appearance and arrangement of the villi on an extended surface.
While the chyle is propelled along the small intestine by the peristaltic action, the matter which it contains in solution is absorbed in the usual manner into the vessels of the villi by the process called osmosis.
The villi of the chorion with the blood-vessels they contain grow so completely into the tissue of the uterus, which is rich in blood, that it becomes impossible to separate them, and they form together a sort of cake.
The villi of the chorion grow larger and more numerous.
At first the villi cover the whole surface, but they afterwards disappear from the greater part of it; they then develop with proportionately greater vigour at a spot where the placenta is formed from the allantois.
If the bladder is opened from the front, as already described, the villi may be nipped off by special forceps and the disease permanently cured.
The villi are slender, branched, filamentous processes which, springing from the floor of the bladder, float in the urine like seaweed.
This is ultimately coated with epithelium, but neither the villi nor the glands of the mucous membrane are ever reproduced.
Remarkable changes have occurred in the smaller vessels, especially in the capillaries and small veins of the villi and submucous tissue.
They were lodged in great quantities within the intestinal glands and behind their epithelium, as well as upon the surface of the villi and within them, and sometimes even in the muscular coat.
Its function is to receive the lacteals which come from the villi of the intestines.
The lacteals are the lymphatics which carry the chyme from the villi of the intestines and deposit it in the receptaculum chyli.
It is in the villi of the intestines that we find the termination of the mesenteric arteries, the beginning of the mesenteric veins and the commencement of the lacteals.
These have their beginnings in the little villi just mentioned, side by side with the blood-vessels.
We have already found that part of the digested food (chiefly carbohydrates, proteins, salts, and water) is absorbed directly into the blood through the walls of the villi and carried to the liver.
By means of the folds and villi the small intestine is estimated to have an absorbing surface equal to twice that of the surface of the body.
The large intestine has somewhat the same structure as the small intestine, except that it lacks the villi and has a greater diameter.
Between thevilli are found the openings of the intestinal glands.
There is no direct communication (except by osmosis) between the fetal chorionic villi and the maternal intervillous blood spaces.
When the ectopic ovum begins to develop in the Fallopian tube the placentalvilli erode the tubal wall and the blood-vessels.
It is soon modified, however, as the villi on one part of the chorion are withdrawn; while on the other part they grow proportionately stronger, and unite intimately with the mucous membrane of the womb.
A short cylindroidal form of cell makes up columnar epithelium, seen typically in the cells covering the villi of the duodenum (Figure V.
This epithelium of the villi has the outer border curiously striated, and this is usually spoken of as leading towards "ciliated" epithelium, to be described immediately.
In the higher mammalia, developed within the uterus, the allantois becomes attached by vascular villi to the uterine wall and establishes a vascular connection between the foetal and maternal blood vessels.
Intestinal villi are found in nearly all mammals and in many birds.
Some birds, such as the snipes, herons and crows, have in place of the intestinal villi projecting folds of the mucosa, often arranged in a reticular manner.
Hence the villi of the small intestine are especially large and prominent in the carnivora, while they are small and insignificant in herbivora and omnivora.
In many forms the digestive secretory and absorbing area is augmented by the development of folds, valves, diverticula, villi and papillae from the mucous surface of the intestine.
The villi are not confined to the two highest vertebrate classes, but are encountered also in the mucous membrane of the midgut in certain reptiles, notably the ophidia.
The villi are peculiar to these parts; they are inversely conical, adhering to the membrane by their smaller end.
These rapidly disappear; and then the villi attract attention.
Injections made retrograde from the thoracic duct, pass through the villi into the intestines.
The fetal and maternal placentas are made up of vascular villi and depressions that are separated only by the thin walls of capillaries, and a layer of epithelial cells.
In ruminants, the villi are grouped at certain points.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "villi" in a variety of sentences. We hope that you will now be able to make sentences using this word.
