During the brief period while the germ within the fertilized egg is being nourished by the vitellus or yolk of the egg, great changes are taking place in the soft and delicate linings which surround it within the womb.
This vitellus or yolk undergoes a series of segmentation or dividings which are known as spontaneous segmentation.
Now, the human ovum or egg consists of a vitellus or yolk, which is covered by a similar membrane, known as the vitelline.
It is formed from the vitellus at a much later period than the proper vitelline membrane.
The vitellus is granular, and provided with a distinct, though delicate membrane, which has every appearance of being a product of the ovum itself rather than of the follicular epithelium.
The Vitellusand the development of the yolk spherules.
Internally to it may be observed very faint indications of the differentiation of the outermost layer of the vitellus into the perforated or radially striated membrane of Schultz, which will be spoken of as zona radiata.
The vitellus is at first faintly granular, but at a later period exhibits a very distinct (protoplasmic) network of fibres, which is still present after the ovum has been laid.
Beneden's nomenclature, a membrane formed by the follicular epithelium, and, by vitelline membrane, one formed by the vitellus or body of the ovum.
It has only been met with in the vitellus of some of the medium sized ova of a young female.
It exhibits frequent changes of form, its membrane becomes gradually absorbed and its outline indented and indistinct, and finally its contents become to a certain extent confounded with the vitellus (Fig.
The vitellus is frequently vacuolated, but occasionally the vacuoles appear to be caused by a shrinking due to the hardening reagent.
Impregnation is external, and on its occurrence a contraction of the vitellus takes place, so that a space is formed between the vitellus and the zona radiata, which becomes filled with fluid.
The ovum is formed of a spherical vitellus without any investing membrane.
When produced in the natural course of things the vitellus undergoes a contraction.
Finally by Semper they are believed not to be cells, but to be amoeboid protoplasmic bodies which are pressed out from the vitellusunder the stimulus of the sea-water or otherwise.
It exhibits frequent changes of form, the reticulum vanishes, its membrane becomes gradually absorbed, its outline indented and indistinct, and finally its contents become to a certain extent confounded with the vitellus (fig.
In Ascidia canina these processes become as long as the whole diameter of the vitellus (Kupffer, No.
There is not unfrequently present in the vitellus a peculiar body known as the yolk nucleus, which is very possibly connected with the formation of the food-yolk.
Situated around the vitellus, or between the vitellus and zona pellucida of an ovum.
Fullness of sperm, or seed; the passage of more than one spermatozoön into the vitellus in the impregnation of the ovum.
Nature forms these living ova, when she takes vitellus and albumen out of the sea-slime, invests them with a shell derived from the earth, and hatches them, after they have been vivified by sun and air.
In the ova of the Dermatozoa or Tegumental animals the vitellus only appears to exist, being without albumen, which first seems to make its appearance along with the animal systems.
The Protozoa correspond to thevitellus or the male semen, which is nothing but vitellus in a state of solution.
In the oviparous animals the secretion of the vitellus is distinct from that of the albumen; the one takes place in the ovarium, the other in the oviduct or uterus.
These animals are vitelluswith the vascular membrane.
If then the Infusoria are the vitellusor seed of the animal kingdom; in like manner the Corals are its ova.
When all the organs are developed, the intestines are drawn together with the vitellus into the abdomen.
The ova of Reptiles possess a vitellus and albumen, and are surrounded by a membranous or sometimes by a calcareous shell.
As the Infusoria are the seed or vitellus itself, so also are they the very ovum, and require no special sexual parts for propagation.
The vitellus is more a product of the thorax, and is therefore formed directly into the intestine and entire embryo.
The vitellus is directly secreted from the arteries, but the albumen from an enteroidal sac or the oviduct, which is finally converted into mammary glands.
The vitellus or semen is point-or nerve-mass dissolved.
The egg is known to consist of two distinct parts, the vitellus or yelk surrounded by its albumen or white; to the former of these we now more particularly refer.
In birds, the covering of the vitellus is called yelk-bag; whereas, in mammalia and man it receives the name of vesicula umbilicalis.
The impregnated vitellus is retained in its capsule in the ovary, precisely as the ovum of the mammifera is in the Graafian vesicle.
The vitellary membrane seems, at this time, to give way, leaving the vitellus of the ovum merely covered by its spherical blastoderma, and encased by the layer of albuminous matter which surrounds it.
Defn: Situated around the vitellus, or between the vitellus and zona pellucida of an ovum.
Defn: Fullness of sperm, or seed; the passage of more than one spermatozoön into the vitellus in the impregnation of the ovum.
Fullness of sperm, or seed; the passage of more than one spermatozo\'94n into the vitellus in the impregnation of the ovum.
Until recently it was regarded as a general rule that, by the partial segmentation of the vitellus a germinal disc was formed, and in this, corresponding to the ventral surface of the embryo, a primitive band.
Thus, in Fishes, the first changes consist in the segmentation of the vitellusand the formation of a germ, processes which are common to all classes of animals.
The vitellus and the membrane of the egg enlarge with the embryo and absorb by endosmosis the nutritive matter necessary for the latter, contained in the maternal blood.
Up to this point the vitellus of the egg, nourished by endosmosis through its membranes, had sufficed for the nutrition of the still very small embryo.
It forms half the number of chromosomes corresponding to the cell of the species to which it belongs, and grows at the expense of the vitellus of the egg.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "vitellus" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: albumen; caviar; egg; eggshell; ovule; spawn; white; yellow
