These began in 1875 and following years with a careful examination of the behaviour of the germinal vesicle in the maturation and fertilization of the ovum.
My specimen exhibits them in every stage of growth, from a minute point to a vesicle the size of a hen’s egg.
The yelk-molecules surrounding the germinal vesicle are not directly transformed into an embryo.
Huxley adds: “These corpuscles appear to be solid, but by the action of dilute acetic acid the interior generally clears up very rapidly, and a hollowvesicle is left of the same size as the original corpuscle.
This vesicle is not visible so long as the eggs have the form of thin disks; it only shows itself when the eggs begin to acquire an elliptical form in the oviduct.
In the one case a solitary vesicle occupies the shaft of the humerus; whilst in the other several “acephalocysts” have taken up their residence within the cancellous structure of the ilium.
After removal from its capsular covering, thevesicle consists of a thick laminated membrane, forming the so-called cuticular layer, and a central granular mass, which subsequently becomes enveloped by a delicate granular membrane.
The water-vascular system was constantly visible, or at least that part of the main channel which expands into a large vesicle immediately above the central point of the tail.
The interior of each vesicle was filled with a fluid, in which there were no free scolices.
The conspicuous contractile vesicle terminating the excretory system is developed to an unusually large extent, exhibiting in its interior multitudes of the well-known active molecular particles.
Supposing also the Diameter of a Vesicle to be 1/50 Part of an Inch, the Surface of the Vesicle will be .
A minutevesicle in a red seaweed, which contains the reproductive spores.
A slender support of any special organ, as that of a capsule in mosses, an air vesicle in alg\'91, or a sporangium in ferns.
An embryo sac or embryonal vesicle in the ovules of flowering plants.
A vesicle or an elevation of the cuticle with an inflamed base, containing pus.
An auditory cyst or vesicle; one of the simple auditory organs of many invertebrates, containing a fluid and otoliths; also, the embryonic vesicle from which the parts of the internal ear of vertebrates are developed.
The inner, or visceral, one of the two lamell\'91 into which the vertebrate blastoderm divides on either side of the notochord, and from which the walls of the enteric canal and the umbilical vesicle are developed.
Situated under a zone, or zona; -- applied to a membrane between the zona radiata and the umbilical vesicle in the mammal embryo.
The mode of extracting it, is to break the shell carefully with a hammer, so as not to crush the fish, and then let out the liquor in the vesicle with a lancet or other sharp instrument.
The shell is about the size of the common whelk, and contains a fish, on whose body appears a vesicle full of a pale yellow, viscid, purulent substance, which constitutes the dye.
A bladder or vesicle caused by the deposition of serous fluid between the cuticle and the derma or true skin, occasioned by the application of a vesicant, or by a burn, scald, or friction.
If a scald, the vesicle should be first pierced with a needle, or what is better, snipped with a pair of scissors, and the water which it contains should be then gently squeezed out.
Hence, it is certainly possible that the germinal vesicle may be impressed with a tendency to produce a long-limbed animal, the full proportional length of whose limbs shall appear only when the animal is mature{471}.
And we know that the germinal vesicle must have been affected, though no effect is apparent or can be apparent till years afterwards,--no more apparent than when these peculiarities appear by the exposure of the full-grown individual.
I have not found a passage so striking as that which occurs a few lines lower "that the germinal vesicle is impressed with some power which is wonderfully preserved, &c.
In the thick fine-grained yelk we find a clear round germinal vesicle of about 1/750 of an inch in diameter, and this encloses a small embryonic spot or nucleolus.
It is a small, flask-shaped vesicle without any physiological significance, which opens into the ureter between the two spermaducts and the prostate folds (vesicula prostatica).
But in these it soon passes away, the one vesicle being divided into several successive parts by transverse constrictions.
In this way is formed at each side, directly under the horny plate of the back part of the head, a small vesiclefilled with fluid, the primitive auscultory vesicle, or the primary labyrinth.
From the gastrula is first formed the spherical embryonic vesicle filled with fluid (gastrocystis, Figure 1.
As the lens separates from the corneous plate and grows inwards, it necessarily hollows out the contiguous primary optic vesicle (Figure 2.
In the labyrinthic water that fills the auscultory vesicle there are small stones at the points of entry of the acoustic nerves, which are composed of groups of microscopic calcareous crystals (otoliths).
Fluid gathers inside it, and thus we get once more a globular vesicle (the blastula); the wall of this is a single stratum of cells, the blastoderm.
At the point where this comes into direct contact with the most curved part of the primary optic vesicle there is a thickening (l) and also a depression (o) of the horny plate (Figure 2.
Alimentary vesicle at the posterior end of the alimentary canal.
Part of 4th or 5th nephridium which corresponds to vesicle of other nephridia.
Section through the caudal vesicle of a Pristiurus embryo belonging to stage H.
Growth from vesicle at the end of a segmental tube to join the collecting tube of the preceding segment.
Portion of segmental organ of 4th and 5th legs, corresponding to vesicle of the other nephridia.
Germinal vesicle of a large ovum from the same ovary, containing a body of a strikingly similar appearance to those in the body of the ovum in A.
This nephridium resembles those of the 4th legs, and differs from all the others in its large size and in the absence of any dilatation giving rise to a collecting vesicle on its external portion (enlarged).
The first three pairs of segmental organs consist only of the vesicle and duct leading to the exterior.
The section contains two examples of the budding out of the vesicle of a segmental tube to form a Malpighian body in its own segment and to unite with the tubulus of the preceding segment close to its opening into the Wolffian duct.
It shews the bilobed condition of the alimentary vesicle and the fusion of the mesoblast and hypoblast at the caudal vesicle.
The segmental tube and opening are not in the plane of the section, but the dilated vesicle is shewn into which the segmental tube opens.
Op represents part of the optic vesicle to one side of the choroid slit.
A minute swelling soon appears at the part, and develops into a vesicle containing serum or bloody matter, and varying in size, but seldom larger than a shilling.
The vesicle which had hitherto protected it, is abandoned, and the part which remains with hooks and sucker is the mother which has produced in this agamous manner the whole colony.
The opening to the exterior of the contractile vesicle has been found here.
In Fucus vesiculosus they arise in lateral pairs; in Ascophyllum they are single and median; in Macrocystis one vesicle arises at the base of each thallus segment; in Sargassum and Halidrys the vesicles arise on special branches.
Towards its extremity it exhibits protuberances which resemble the rudiments of ramuli, or they terminate in a vesicle which gives rise to a slender filament.
The vesicle as a rule does not exceed a pin head in size but may become as large as a pea.
Simultaneously, there appears an eruption which characteristically consists of wheals surrounded by a vesicle (fig.
The growth of the Graafian vesicle and its contained ovum was supposed to cause an irritation of the nerves of the ovary, which was reflected to the entire nervous system.
Germ cell, a small, round vesicle situated in the ovaries, and which, when fecundated, constitutes the rudiments of the embryo.
The cerebral vesiclewhich represents this is a plain cavity without true subdivision into ventricles.
Into this the cerebral vesicle of the larval lancelet opens.
Some really are, and others closely resemble, the larval conditions of creatures higher in the scale, and the contracted vesicle with its channel bears resemblance to what is called the "water vascular system" of worms.
By careful observation of the bodies of Vorticellids, a contractile vesiclemay be observed, which appears to cause a movement of fluids, that is probably connected either with respiration or secretion.
The anus is situated on the back close beneath the ciliary circle;" and the "contractile vesicle on a level with the ciliary wreath.
Footnote 153: [It is almost certain that this vesicle is not derived from the nucleus, but from the cytoplasm of the sperm-mother-cell.
Furthermore, the spermatozoids in the mosses and vascular cryptogams throw off a small vesicle before performing their functions[153].
A third group, essentially marine, consists of those with reticulated pseudopodia, and usually destitute of distinct nucleus and pulsating vesicle (Fig.
The first and highest includes those which have lobate or finger-like pseudopods, and a well-developed nucleus and pulsating vesicle (Fig.
In others the branches radiated from a central film which may have been a hollow vesicle or float, enabling them to live at the surface of the water (Fig.
While the above changes are taking place in the embryonic membranes, the blastodermic vesicle greatly increases in size, and forms a considerable projection from the upper wall of the uterus.
The space between this membrane and the umbilical vesicle with the attached embryo is obviously continuous with the body cavity (vide figs.
The trabeculae, so far as their mere anatomical relations are concerned, play the same part in forming the floor for the front cerebral vesicle as the parachordals for the mid- and hind-brains.
Hence, when the involution of the lens takes place, the direction in which the front wall of the vesicle is pushed in is not in a line with the axis of the stalk, as for simplicity's sake has been represented in the diagram (fig.
Accompanying this involution, which forms the rudiment of the lens, the optic vesicle is doubled in, its front portion r being pushed against the back portion u, and the original cavity of the vesicle thus reduced in size.
The small size of the umbilical vesicle in Orycteropus indicates that its discoidal placenta is not, like that in Carnivora, directly derived from a type with both allantoic and umbilical vascularization of the chorion.
In its earliest condition the fore-brain forms a single vesicle without a trace of separate divisions, but very early it buds off the optic vesicles, whose history is described with that of the eye.
The optic nerve in Elasmobranchii is not included in the folding to which the secondary optic vesicle owes its origin, and would seem to perforate the walls of the optic cup only at the distal end of the processus falciformis.
Before the two limbs of the amnion are completely severed, the epiblast of the umbilical vesicle becomes separated from the mesoblast and hypoblast of the vesicle (fig.
The vesicle which matures in her ovaries, and is discharged from them by menstruation, remains some days in the womb before it is passed forth and lost.
For this vesicle we have mentioned is in fact an egg, similar in structure to those which birds, fish, and turtles deposit.
A vesicleis first produced, and then a contraction appears around the vesicle, and this contraction increases till a portion of the vesicle is cut off and swims away free like an amoeba.
The embryonic area is the only part of the ovum which has to do with the subsequent development of the embryo; the other parts of the blastodermic vesicle become subservient as nutritive or supporting structures.
As has been said, the very first appearance of these organs takes the form of a pair of outgrowths, or processes, which are hollow, from the front part of the anterior vesicle of the brain.
Part of the posterior vesicle ultimately develops into the cerebellum, or little brain.
