The yelk is a granular albuminous fluid, contained in a granular membranous sac (the blastodermic membrane) which is covered by an investing membrane called the vitelline membrane or yelk-bag.
It unites with the common stem of the allantoic and vitelline veins in front of the liver.
On its way it receives, on its outer side, numerous branches from the venous network, which connect by their anastomoses the posterior branch of the vitelline vein and the sinus terminalis.
The ovum at the time of impregnation has the form of a large spherical mass, similar to the yolk of a bird's egg, but without a vitelline membrane[18].
In Mammalia the superior mesenteric artery arises from the vitelline artery, which may probably be regarded as a primitive caeliaco-mesenteric artery.
They are developed very early, and at first course along the still widely open somatic walls of the body, and fall into the single vitelline trunk in front.
From the vascular area part of the blood returns directly to the sinus venosus by the main lateral trunks of the vitelline veins (R.
The hinder end of the heart is continued into two vitelline veins, each of which divides into an anterior and a posterior branch.
The right allantoic vein disappears before long, and the common trunk formed by the junction of the vitelline and allantoic veins becomes considerably elongated.
The rest of the blood brought by the vitelline arteries finds its way into the lateral portions of a venous trunk bounding the vascular area, which is known as the sinus terminalis, S.
The vitelline vein, which as the yolk becomes gradually absorbed proportionately diminishes in size and importance, comes to appear as a mere branch of the portal vein.
Small intestine of the red-throated loon, Urinator lumme, showing persistent caecal pouch, the remnant of the vitelline duct.
The peripheral segment of the omphalo-mesenteric artery disappears with the cessation of the vitelline circulation.
The middle segment of the intestine, presenting a spiral valve in the interior, gives rise to a vein emptying into the portal vein which corresponds to the subintestinal vitelline vein of the mammalian embryo (Fig.
The arteries supplying the yolk-sac and subsequently the intestinal canal are the vitelline or omphalo-mesenteric.
Proximal segment, formed by the continuation of the proximal part of the vitelline veins into the sinus venosus of the heart.
In the Selachians the liver arises as a ventral outgrowth at the hinder end of the foregut immediately in front of the vitelline duct, thus bringing the liver from the beginning into close proximity with the vitelline veins entering the heart.
The intestinal gutter is thus converted into a closed tube except at the point of implantation of the vitelline duct during the persistence of this structure.
When the hepatic outgrowth buds from the duodenum the vitelline veins send out branches which break up into a wide-meshed capillary network in the mesodermic tissue enveloping the hepatic cylinders.
The two forks embrace between them the omphalo-mesenteric or vitelline veins just before they empty into the sinus venosus of the heart.
When the egg is nearly ripe, and the vitellinemembrane has been reduced to a mere remnant, the follicular epithelium is still very columnar (Pl.
At this time the vitelline membrane appears frequently to exhibit a distinct stratification, dividing it into two or more successive layers.
The big cells have now become flask-shaped like those in Scyllium, and send a process down to thevitelline membrane.
It is formed from the vitellus at a much later period than the proper vitelline membrane.
The stage of about the greatest development of both the vitelline membrane and zona radiata is represented on Pl.
A vitelline membrane with a crater-like opening has become distinctly formed.
It becomes thevitelline membrane of Leydig, the albuminous membrane of Gegenbaur, and homogeneous membrane of Schultz.
I have not been able definitely to decide the relation of the zona radiata to the first formed vitelline membrane.
In the majority of cases all the ova of each nest are quite distinct, and each provided with a delicate vitelline membrane (fig.
Fol finds that when the impregnation has been too long delayed the vitelline membrane is formed with comparative slowness and several spermatozoa are thus enabled to penetrate.
It will be convenient to treat the history of sections of the alimentary tract in front of and behind the vitelline duct separately.
Defn: Of or pertaining to the yolk of eggs; as, the vitelline membrane, a smooth, transparent membrane surrounding the vitellus.
Two vitelline membranes, one perforated and the other homogeneous, may coexist at the same time, e.
The three vitelline spheres, still largely uncovered by the epiblast, lie at the posterior end of the body.
Eventually, together with part of the protoplasm of the vitelline spheres, they appear to give rise to a layer of hypoblastic cells.
Semper believed that the tubes were continuous with the three posterior vitelline cells, but this has been shewn not to be the case.
The ova become eventually detached by the stalk rupturing, and the portion of it which remains attached to the vitelline membrane falling off.
A vitelline membrane is formed when the ova are mature.
The ovum is invested by a vitelline membrane and undergoes development in a brood-pouch at the base of the inner gill lamella.
In the Tench it has been observed by Bambeke to penetrate into the vitelline sphere.
The ovum is enclosed in a delicate vitelline membrane, enveloped in its turn by a chorion secreted by the walls of the oviduct.
This coagulation forms the vitelline membrane, which prevents the entry of other spermatozoids.
The united vitelline veins open into the posterior end.
The only membrane enclosing the individual eggs is the vitelline membrane.
Each egg is encased in a vitelline membrane, but individual outer envelopes are lacking.
Vitelline vessels in the germinative area of a chick-embryo, at the close of the third day of incubation.
These vessels naturally atrophy with the degeneration of the umbilical vesicle, and the vitelline circulation is replaced by a second, that of the allantois.
The heart divides behind into the two vitelline veins, which expand in the germinative area (which is torn off all round).
On the floor of the open belly lie, between the protovertebrae, the primitive aortas, from which five pairs of vitelline arteries are given off.
The embryo is already entirely enclosed in the amnion, and is only connected in the middle of the belly by the vitelline duct with the embryonic vesicle, which changes into the yelk-sac.
The yelk-sac is reduced to a small pear-shaped umbilical vesicle; its thin pedicle, the long vitelline duct, is enclosed in the umbilical cord.
The more the embryo grows, the smaller becomes the vitelline (yelk) sac.
Thus, the secondary, allantoic circulation gradually takes the place of the original vitelline circulation.
The whole of the primitive gut-cavity is completely closed, and is merely connected in the middle by the vitelline duct with the equally closed cavity of the embryonic vesicle (Figure 1.
As the separation of the substances composing the ovum is an advancing-step towards their improvement, so also is the removal of the albumen-glands from the vitelline sac a nobler condition.
The intestine respires through thevitelline vessels, the vascular system through the vessels of the chorion, the sexual system through those of the allantois, the integument through the branchial apertures.
The Vitelline animals are sentient or nerve-points, which have combined all other processes in this identical mass.
This becomes also during incubation consumed in the formation of the body of the chick, and not the vitelline mass, which is first of all destined for the intestine.
Without doubt also the vitelline vessels respire, and thus each vegetative system has its own process of respiration.
These ovaria, which now secrete semen instead of vitelline vesicles, are called testes.
The secernent point of the vitellinemembrane or of the umbilical vesicle is the coecum.
The true cæcum of the bird is the vitelline canal or duct, just as in the fishes and all higher organized animals; this being distinctly retained in the aquatic birds.
The chick is still nourished several days after exclusion from the egg by the vitelline mass, which passes through the vitelline canal into the intestine.
Their vascular system forms an exceedingly regular, quaternary net, with branches and ramules ranging opposite to each other, which have been believed to be the vitelline network of the ovum when hatched.
Hence Reptiles have originally also a coecum, but it has for the most part disappeared; like its antetype the vitelline canal, which is so small in most Fishes and Birds, as to be scarcely distinguishable.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "vitelline" in a variety of sentences. We hope that you will now be able to make sentences using this word.
