Karyokinesis

“ The polar and spindle-like radiations visible during the process of karyokinesis, which have already been referred to, and the presence of the centrosome, possibly even during the resting stage of the cell, furnished additional illustrations of differentiation within the cell plasm. In many cells there appears also to be a difference in the character of the cell plasm which immediately surrounds the nucleus and that which lies at and near the periphery of the cell. ”

“ According to the very recent works of M. Van Beneden upon Ascaris megalocephala, the great nematoid of the horse, there is no fusion whatever between the two pronuclei. They always remain distinct. Each passes through, separately, all the phases of karyokinesis, when the fecundated ovum divides. In this connection the recent observations of M. Balbiani confirm the opinion of Van Beneden, who had been sharply attacked by Carnoy and Zacharias. First, in each of the two pronuclei each reticulate substance is observed to present the initial phases of karyokinesis ”

“ After fertilization the nucleus of the egg divides, the first stages of karyokinesis being apparent even before complete fusion of the male and female nuclei has occurred. The result of this is the production of four nuclei, which eventually take up a position at the bottom of the ovum and become separated from one another by vertical cell-walls; these nuclei divide again, and finally three tiers of cells are produced, four in each tier. In the Abietineae the cells of the middle tier elongate and push the lowest tier deeper into the endosperm ”

“ The capillaries around the seat of injury dilate slightly, the fixed cells of the tissues become active, dividing by karyokinesis as already described. The endothelial cells lining the divided blood vessels multiply and take an active part in the process. In spite of the congestion and the new cells produced, the reaction is much less than that of inflammation. The new cells invade the blood clot, consuming it and also any foreign matter, or any tissue which may have been killed by the injury. ”

“ The erythroblasts continue to multiply by karyokinesis in early foetal life, especially in the liver, spleen, bone marrow and lymphatic glands, though later on their formation only occurs in the red bone marrow. In most of the erythroblasts the nucleus soon becomes contracted, and the cell is then known as a normoblast, while ultimately the general view is that the nucleus disappears by extrusion from the cell and the non-nucleated red blood plates or erythrocytes remain. ”

“ This interpretation of ordinary karyokinesis is less uncertain than perhaps at first sight it may appear to be. We cannot, it is true, directly see the ancestral germ-plasms, nor do we even know the parts of the nucleus which are to be looked upon as constituting ancestral germ-plasm; but if Flemming’s original discovery of the longitudinal division of the loops lying in the equatorial plane of the nuclear spindle is to have any meaning at all, its object must be to divide and distribute the different kinds of the minutest elements of the nuclear thread as equally as possible. ”

“ One of the most typical cases of centrosomes in plants is that described by Swingle in 1897 as occurring in Stypocaulon (114) . Here a minute, deeph' staining, dumb-bell-shaped body occurs at the pole of the spindle in karyokinesis, which at the close of division divides into two. Both of these remain in close connection with the nuclear membrane, but travel in opposite directions until they come to lie at opposite points on the equator of the nucleus. ”

“ In the period between 1870 and 1880 observations were made by Schneider, Strasburger, Bütschli, Fol, van Beneden and Flemming, which showed that the division of the nucleus and the cell was due to a series of very remarkable changes, now known as indirect nuclear and cell division, or karyokinesis. The changes within the nucleus are of so complex a character that it is impossible to follow them in detail without the use of appropriate illustrations. ”

“ It has been already established that various forms of nuclear division occur at different periods of spermatogenesis. I make this assertion, not only from my own observations, but also from observations which have been made and insisted upon by others. Thus, van Beneden and Julin [266] stated in 1884 that direct and karyokinetic nuclear divisions alternate with each other in the spermatogenesis of Ascaris megalocephala. Again, Carnoy [267] distinctly states that the different cell-generations in the same testis may not uncommonly exhibit considerable differences as regards karyokinesis. ”

“ Each female gametocyte gives rise to only a single female element (megagamete) , after a process of nuclear purification. The karyosome is expelled from the nucleus into the cytoplasm, where it breaks up at once into fragments (VII. ♀) . Meanwhile the gametocyte is becoming spherical, and its changes in shape aid in setting it free from the shrivelled host-cell. The fragments of the karyosome, which are, as it were, squeezed out to the exterior, exert a powerful attraction upon the microgametes, many of which swarm round the now mature megagamete. ”

“ Frequently one only is present in each cell, but more can occur. The body substance is composed of a more or less finely granular or distinctly alveolar protoplasm which exhibits no differentiation into ecto- and endoplasm. All species possess a nucleus that enlarges with their growth; sometimes it only shows through the cytoplasm as a lighter spot, or may even be quite concealed. It is vesicular, and besides containing very delicate threads of chromatin in the clear nucleoplasm, it contains generally only one large karyosome. ”

“ Abstract The exocytosis of synaptic vesicles (SVs) elicited by potent stimulation is rapidly compensated by bulk endocytosis of SV membranes leading to large endocytic vacuoles (‘bulk’ endosomes) . Subsequently, these vacuoles disappear in parallel with the reappearance of new SVs. We have used synapses of dynamin 1 and 3 double knock-out neurons, where clathrin-mediated endocytosis (CME) is dramatically impaired, to gain insight into the poorly understood mechanisms underlying this process. ”

“ The tissue-elements, particularly the nuclei, must be preserved as perfectly as possible so that they will not be affected by further procedures of microscopic technique. The chemic properties of physiologic and pathologic substances must likewise be preserved. The preservation of karyokinetic figures is [Pg 226] a criterion of good fixation. In pathologic work it is also desirable that the fixing agent should preserve the red blood cells, and permit of the staining of bacteria in sections. ”

“ What is the prognosis of carbuncle?
Occurring in those greatly debilitated or in late life, and in those cases in which two or more lesions exist, or when seated about the head, the prognosis is always to be guarded, as a fatal result is not uncommon. In fact, in every instance the disease is to be considered of possible serious import. [Pg 72]
What constitutional treatment is usually employed in carbuncle?
A full nutritious diet, the use of such remedies as iron, quinia, nux vomica, with malt and stimulants, if indicated. ”

“ From a pathological point of view the subject of chemiotaxis must be considered along with that of phagocytosis. Certain free mobile cells within the body, such as blood-leukocytes, as well as others which are fixed, as for instance the endothelium of the hepatic capillaries, have the property of seizing upon some kinds of particulate matter brought within their reach. Within a quarter of an hour after a quantity of cinnabar has been injected into the blood of the frog nearly every particle will be found engulfed by the protoplasm of the leukocytes of the circulating blood. ”

“ The best understood relies on a protein called clathrin, and is thought to be essential for nervous system function. Recently, however, a mechanism of vesicle membrane endocytosis that does not involve clathrin was identified. This mechanism, called bulk endocytosis, involves reinternalizing large regions of the cell plasma membrane to generate large compartments called vacuoles, from which new synaptic vesicles eventually form. This mechanism has been observed when neurons fire at high frequency. ”

“ It is an observed fact that blood outside the body soon develops the property of auto-hæmolysis. If blood is drawn from a vein, put into a test-tube, and allowed to clot, then after twenty-four hours or more the serum which has separated from the clot begins to be tinged with hæmoglobin, even though it has remained absolutely sterile. It appears, therefore, that the serum develops a hæmolysin and the corpuscles the corresponding iso-hæmolysin, the interaction of which results in the breaking up of corpuscles. ”

“ High K+ stimulation induces bulk endocytosis, as assessed by CTX-HRP, at both WT and dynamin mutant synapses.Following incubation in resting buffer (R) , neurons were stimulated with 90 mM K+ for 90 s, then incubated in resting buffer for 10 and 30 min. CTX-HRP, added either during or after the stimulus (A) , or selectively after the stimulus (B) , was used as an endocytic tracer. In all genotypes, loss of SVs during the stimulus is compensated by the appearance of numerous bulk endosomes. ”

“ A portion of the cellular protoplasm is necrosed and destroyed. In these cases the nuclei have already undergone a change; although their contours may be well defined, we discover in their interior only a very little chromatin in the form of small granulations, and the nuclear fluid takes a feeble stain with basic colours, since it contains a little chromatin in solution.
When the protoplasm of the hepatic cells has suffered more pronounced lesions, the changes in the nuclei are also more marked ”

“ Interestingly, dynamin 1 is constitutively phosphorylated in resting nerve terminals and its Ca2+ triggered dephosphorylation upon synaptic stimulation results in its binding to the F-BAR domain containing protein syndapin/pacsin ( [33] ; [29] ; [34] ) , which has also been implicated in bulk endocytosis ( [35] ) . However, studies of dynamin 1 knock-out (KO) neurons have indicated the occurrence of robust bulk endocytosis even in the absence of dynamin 1 ( [17] ) , in spite of a strong impairment of CME ( [36] ; [37] ) . ”

“ We demonstrate that the rapid, bulk endocytic recapture of SV membranes induced by a strong stimulus, either KCl or high frequency stimulation, is not impaired at synapses lacking both of the two predominant neuronal dynamins, dynamin 1 and dynamin 3, that is synapses where CME is severely perturbed ( [36] ; [10] ; [28] ) . Conversion of bulk endosomes into new SVs does occur in these synapses, although less efficiently than in wild-type (WT) synapses. ”

“ When the schizogony ceases, the merozoites, that had penetrated the epithelial cells and become trophozoites there, consist of two kinds of differently constituted individuals. One kind possesses a clear cytoplasm (fig. 67, XII) , the other an opaque, richly granular cytoplasm (fig. 67, XI) , while both possess a vesicular nucleus with a karyosome. In order to continue their development, the more granular individuals must be fertilized, and are therefore termed either female gametes or, on account of their size, macrogametes. ”

“ In both diseases the lesion is ascending: in tabes disturbance of sensibility occurs first in the distribution of the sensory fibres of the ulnar nerve; in cervical pachymeningitis the flexors and intrinsic muscles of the hand are first paralyzed. Hence it is to be inferred that the central nucleus for the latter muscles lies in the lower, that for the extensor muscles in the middle, segment of the cervical enlargement of the cord. ”

“ This may be explained by a more or less active perichondritis when the injection is made over the cartilage, the inflammation, thus set up, being of longer duration than where the skin and bone or areolar tissue are involved. Any subsequent injection should not be undertaken until at the end of two weeks or more for the reasons above stated.
The injected mass at all times should be introduced under normal pressure, never to the extent of rendering the skin above it white in color. The mass should also be molded out with the tip of the finger or the rounded, dull handle end of a scalpel. ”

“ By long study of sections of carcinomatous tissue he claims that the mononuclear leukocyte behaves in a very different manner from the polynuclear. Briefly he charges the mononuclear white corpuscles with actually producing the disease, by conjugating with certain epithelial cells, thereby giving them the reproductive capacity which enables them to push forward on their destructive career. The polynuclears seem to come up to the defense of the body, but are overcome by the poison secreted by the rapidly growing tumor cells. ”

“ Our results demonstrate that SV reformation following a strong, acute, secretory stimulus (either high K+ depolarization or high frequency electrical activity) occurs predominantly via the budding of SVs from endosomal intermediates generated by bulk endocytosis (bulk endosomes) . ”

“ Emaciation advances rapidly. The temperature may oscillate from day to day or it may rise steadily to a climax, and 580then descend suddenly when collapse occurs. In all cases the protozoön is found in the red globules, or free in the blood. In the worst cases the red globules may be so reduced in number that they can scarcely be found. Death comes usually by collapse. In some instances the hæmoglobinuria may be absent yet the disease advances to a fatal result.
Lesions. The carcass is usually shrunken and emaciated and exhales a fœtid odor. ”