What is there in the embryonal germ that evolves out of the materials stored up therein a frame similar to the parents?
In the development of the human body in the embryonal stage the energy of cell-division is most intense in the early cleavage stage, and this diminishes as the limit of growth approaches because further division is not needed.
There is a structural differentiation in the unsegmented ovum, with all the embryonal axes foreshadowed in it, but this tells us nothing more than that the egg contains the man in germ.
Of the monstra per defectum the commonest are caused by a failure of closure in the embryonal medullary canal, which leaves part of the brain and spinal cord or their bony covering lacking.
The basis of the lesion is in a collection of small round embryonal cells resembling lymph-cells, arranged in the connective tissue around the arterioles which come from the tunica albuginea.
As the process progresses the epithelial cells become fatty, degenerated, and subsequently broken down and absorbed, while the embryonal interalveolar tissue rapidly organizes into fibrous tissue.
The addition of horses’ dung to soft wet mud in one case, and of cows’ dung in another, neither appeared to advance nor retard the process of embryonal formation, so long as the embryos were enclosed in their shells.
That to the left shows mulberry cleavage of the yolk; the other having lost its embryonal contents by rupture.
Those eggs, however, in which the yolk-segmentation had not arrived at the early embryonal stage remained unaffected.
Here, again, there was no room for doubt as to their source, especially as they individually displayed different degrees of organisation, all answering to one and the same embryonal type.
The embryonal larvæ would be killed by an admixture of sewage.
According to Davaine, however, embryonal development is thus arrested (except in Ascaris tetraptera of the mouse).
The transition from the embryonal state to the higher larval conditions is accompanied by a change of skin, after which the digestive and reproductive organs are gradually but rapidly formed and completed.
Whilst still in the egg, one end of the primitive embryonal mass becomes gradually narrowed, cilia at the same time appearing.
The class of Birds (Aves), as already remarked, is so closely allied to Reptiles in internal structure and by embryonal development, that they undoubtedly originated out of a branch of this class.
However, in these latter also the cloaca formation exists during the first period of their embryonal life, and the separation of the two openings takes place only at a later date (in man about the twelfth week of development).
Nevertheless, this interrelation must be understood in a very wide sense, and is modified according to the period of embryonal or extrauterine life at which a lesion or a radical disturbance in development chances to occur.
The human countenance, that is so marvellously beautiful in our superior hybrid races, passes, during its embryonal life, through many forms that are very far removed from such perfection.
This form of cranium, seen from above, is that of an ovoid, with the broader portion corresponding to the parietal bones, at the point where the characteristicembryonal nodules are situated.
Upon her rests not only the responsibility of preserving the integrity of the germ, but also that of the embryonal and foetal development of man.
Illustration: fertilized ovum embryo foetus and new-born child child] From the little black point to the big circle are represented the different stages of embryonal and foetal development, until we reach the child.
It is not until later that the external nose is formed (middle of the second month of embryonal life).
The protuberances, however, are quite smooth and not pointed, as in the embryonal cranium.
In this form, persistent traces of the five primitive embryonal nodules are still plainly visible, giving the contour of the cranium, when seen vertically, the appearance of a pentagon.
The significance of this is not always the same: for example, the diastema between two upper incisors indicates a very slight anomaly of embryonal development, and, some people think, gives a sympathetic charm to the smile.
Note the analogy between the different parts of the head in animals and in man; every species, however, has special embryonal characteristics.
Those naturalists who accept in any form the theory of evolution, consider that "the embryonal state of each species reproduces more or less completely the form and structure of its less modified progenitors.
The ventral nervous mass has the form of a broad band, with straight sides; it consists of embryonal cells, and remains in this undeveloped condition during the whole larval state.
He it was who drew special attention to the remarkable parallelism between the embryonal and the palaeontological development--between ontogeny and phylogeny, which I have already (p.
Separate duodenal openings of biliary and pancreatic ducts, resulting from failure of development of distal embryonal pancreatic bud.
To avoid confusion, and to bring the salient points into strong relief, the majority of the diagrams illustrating human embryonal stages are purely schematic.
As previously stated the normal type of the human embryonal caecum is represented by the pouch of some of the new-world monkeys, as Ateles (Fig.
In contradistinction to the adult organs just noted the yolk-sac or umbilical vesicle is merely a temporary embryonal appendage to the alimentary canal.
Any condition which will prevent or delay this apposition will likewise perpetuate the original embryonal condition of the tube, completely invested by peritoneum and with a free mesocolon.
Embryonal area of sheep, composed of ectoderm and entoderm.
The disposition of the structures illustrated by this example probably depends upon delayed adhesion of the colic embryonal tube to the dorsal parietal peritoneum.
The arrangement of the large intestine in this animal illustrates the earlyembryonal stage in the development of the complete ruminant spiral coil (cf.
Common embryonal condition, as illustrated by cat, after rotation and formation of omental bursa.
It is obvious that were the embryonal theory of origin, as extended by Cohnheim, universally applicable, the growth demands something more than a focus of embryonal cells.
Although certain tumors are admitted to be due to congenital peculiarities of tissue, and even to represent atypical growths from embryonal tissue, the theory of such an embryonal origin for all tumors seems unnecessary.
All tumors may thus be said to have an embryonal origin.
The alternative remains that theembryonal cells are those whose derivatives are present in, and form the essential element of, the morbid growth.
The tendency of the present seeks for a local cause, and the most recent theory, that of Cohnheim, demands an accumulation of dormant embryonal cells as such a cause.
The connective-tissue elements in the derma are also swollen, and exhibit reversion to the embryonal state.
As the growth of embryonal tissues is so defined that descendants are like their ancestors in all respects, so the development of tissues in the adult is regarded as defined with equal precision.
Now the entire embryonal development of the human child is in reality no more than a continuous process of ecphoration of old engrams, one after another.
A striking characteristic of compound terata is that the individuals are always of the same sex; moreover, the embryonal development of reproductive organs in general is such as almost to preclude a question of duality of personality.
An attempt has been made (Pflueger) to explain this phenomenon in the human subject on the ground that the tenacity of life in the female sex in the period of embryonal existence exceeded that of the male.
The embryonal germ, before its fertilization, is an embryo whose sexual development is undetermined.
In this condition it remains for seventeen days, when it throws off its embryonal membrane, and becomes detached from the shell.
At this period the embryo is partially organized, having faint traces of segments, and is still enveloped in its embryonal membranes and retains its connection with the shell.
The two outer ones multiply by subdivision and form the embryonal membrane, or "amnion," which is a provisional envelope and does not assist in building up the body of the germ.
The embryo-sac is not figured in this early condition, the embryonal vesicle being then smaller than that in fig.
The neck contains a slender canal, and within the base is a special embryonal cell, from which the capsule is subsequently formed.
The end of the pollen-tube then adheres to the embryonal vesicle, and such interchange of cell-contents takes place between them as effects fertilization.
The embryonal cell grows by subdivision, so as to form a stalk-like body, which as it rises extends the archegonium upwards until it splits across near the base.
The process of cell-formation in the fertilized embryonal vesicle then takes place rapidly, new cells being formed by the division of its cell-contents (Pl.
The embryonal structures are very difficult of detection; but it happens that in our little chickweed they are more easily dissected out than in most other plants.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "embryonal" in a variety of sentences. We hope that you will now be able to make sentences using this word.
