Telos

“ It is not primary constituents that the germ contains, according to Delage, it is chemical substances, for instance muscle substances, probably 'les substances caractéristiques des principales catégories de cellules, c'est-à-dire, celles qui, dans ces cellules, sont la condition principale de leur fonctionnement.' All these must be contained in the ovum. How they are to reach their proper place in the organism, how the 'characteristic chemical substance' of a mole is to land just behind the right or left ear of the fully formed man, is not stated. ”

“ Instead of the latter, we find in these cells a roundish, nucleus-like form in the protoplasm, which also takes the nuclear stains, and possibly is to be considered an accessory nucleus. We have received the impression that we have here to deal with a vacuole filled with substance secreted by the cell. In a large series of preparations, it is possible to obtain some elucidation of the development and fate of these appearances. They first appear as point-like granules in the protoplasm, bearing no relation to the cell nucleus; they gradually increase, and acquire a considerable circumference. ”

“ Ectoderm cells, and possibly also some primitive endoderm cells, also take part in forming the test. Many of these cells in the test remain small and simple, as the fusiform and stellate test-cells; some become pigment-cells, while others enlarge and become vacuolated to form the large (up to 0.15 mm. in diameter) vesicular or "bladder" cells—this is especially the case in the outer layer of the test in Ascidia mentula (see Fig. 17, bl) where there are innumerable clear vesicles, each surrounded by a thin film of protoplasm and having the nucleus still visible at one point of the surface. ”

“ During segmentation there arises a layer of small superficial cells (epiblast) and a central layer of larger cells, which becomes separated from the former by a segmentation cavity, except at the pole adjoining the free end of the brood-pouch. At this point the epiblast cells become invaginated into the central cells and form the alimentary tract, while the primitive central cells remain as the mesoblast. A fold arises from the epiblast which Todaro compares to the vertebrate amnion, but the origin of it is unfortunately not satisfactorily described. ”

“ The telomerase numbers from yesterday's blood sample are not encouraging. As I told you, your topical enzyme application has metastasized into your bloodstream and started to replicate, just like it did in Kristen. We're seeing a process known as 'engraftment.' These special cells have learned to mimic any cell they come near. They become the tissue that those cells comprise and begin replacing the healthy tissue with new. ”

“ The nucleus of the cells loses its more or less distinct network, and becomes very granular, with a few specially large granules (nucleoli) . The protoplasm around it becomes clear and abundant—primitive ovum stage. It may be noted that the largest primitive ova are very often situated in the pseudo-epithelium. (b) A segregation takes place in the contents of the nucleus within the membrane, and the granular contents pass to one side, where they form an irregular mass, while the remaining space within the membrane is perfectly clear. ”

“ The growth of the outer membrane of the blepharoplast in thickness and the appearance of granules in the structure of the membrane is evidently correlated in some way with the disappearance of its contents. When the daughter nuclei organize in an early telophase, they are at first strikingly small in comparison with the organizing daughter cells and the nucleus of the mother cell. Figure 35 shows a drawing of a fairly early telophase, and a photomicrograph of the same cell is shown in figure 63. ”

“ Then the primary cell resolves itself into a cluster of peculiar secondary cells, each consisting of an elongated body containing an orange-coloured endochrome and a pair of long flagella, as seen in the antherozoids of the higher cryptogams. As the sperm-cells approach maturity the clusters may be seen to move within them; the bundles then separate and show an independent active movement while still within the cavity of the primary cell, and finally escape through a rupture in the cell-wall, rapidly diffusing themselves as they pass through the cavity. ”

“ In the process of division the cells gradually separate at the suture, and a new half-cell is formed upon each old half, which grows until it attains the size and form of the original half of the parent-cell. The conjugation is effected by two cells approximating so that their sutures are near together, the cells then{74} open at the sutures, and the effused contents become united to form a spore or sporange, from which one or more individuals are formed. These spores are often elegantly spinous on the surface. ”

“ Such a size is just sufficient to produce, in a certain time and under certain external conditions, the nuclear substance necessary for the construction of the embryo, and to start the long series of cell-divisions. When the segmentation nucleus is smaller, but large enough to enter upon segmentation, the nuclei of the two first embryonic cells will fall rather more below the normal size, because the growth of the segmentation nucleus during and after division will be less rapid on account of its unusually small size. ”

“ The cells forming the inner side of this pocket form the primitive germ-cells, which {490}constitute the main mass of the ovoid gland; those of the outer side remain thin. The cavity of the ingrowth is shut off from the general coelom, but persists throughout life. In Asteroids a similar ingrowth takes place, but both walls thicken and become converted into germ cells, and the cavity disappears, and, as in Asteroidea, a considerable number of the germ-cells in the stolon degenerate. ”

“ The basis or ground-substance of the outer cell of osseous tissue may be converted, by deposition of lime-salts, into bony matter, through which the fibrils extend from the nuclei in open channels. If this theory be correct, the original cell becomes a nuclear center of active protoplasm and an outer region whose ground-substance is converted into bone, while its protoplasmic fibrils extend until they join similar fibrils of other cells, thus converting the whole mass into a living network whose interspaces are occupied with bone. ”

“ He holds the outer layer to be a provisional layer of protective cells, forming part of the wall of the original vesicle, the middle layer he regards as the true epiblast and the inner layer as the hypoblast.
During the sixth day he finds that the cells of the outer layer gradually cease to form a continuous layer and finally disappear; while the cells of the middle layer become columnar, and form the columnar epiblast present in the embryonic area at the end of the sixth day. The mesoblast first takes its origin in the region and on the formation of the primitive streak. ”

“ After he moved his research team into the Dorian Institute just over 4 1/2 years ago, he had perfected a way to use a human protein, an enzyme called telomerase, to make adult stem cells do most of the miracles once only thought possible with embryonic cells.
The phase‐three clinical trials over the past seven months had proved conclusively that the technique worked. Adult stem cells, when treated with the telomerase enzyme to arrest the process of cell senescence, could indeed regenerate everything from the human brain to the human heart, from Parkinson's to acute myocardial infarction. ”

“ The former, for instance, contains a rounded nucleolus or “germinal spot,” certain conspicuous granules or strands of the peculiar substance called chromatin, and a coarse meshwork of a protoplasmic material known as “linin” or achromatin; the outer protoplasm, or cytoplasm, is generally believed to consist throughout of a sponge-work, or rather alveolar meshwork, of more and less fluid substances; and lastly, there are generally to be detected one or more very minute bodies, usually in the cytoplasm, sometimes within the nucleus, known as the centrosome or centrosomes. ”

“ Intermediate Cell-mass. At about the period when the muscle-plates become completely free, a fusion takes place between the somatopleure and splanchnopleure immediately above the dorsal extremity of the true body-cavity (Pl. 11, fig. 6) . The cells in the immediate neighbourhood of this fusion form a special mass, which we may call the intermediate cell-mass—a name originally used by Waldeyer for the homologous cells in the Chick. Out of it are developed the urinogenital organs and the adjoining tissues. ”

“ The cell-wall is of cellulose. The cell contains two chloroplastids, or plates coloured with the vegetal pigment "diatomin." Besides ordinary transverse fission in the ordinary encysted state in the ectoplasm of the host, when free they may pass into what is known as a "Palmella-state," the cell-walls gelatinising; in this condition they multiply freely, and constitute a jelly in which the individual cells are seen as rounded bodies. They contain starch in two forms—large hollow granules, not doubly refractive, and small solid granules which polarise light. ”

“ The bundle-sheath of the young stem is more easily recognised than in the older stem. It is, in fact, a continuous layer of cells, whose radial walls have a characteristic dark spot on each radial wall. The bundle-sheath lies immediately outside the vascular bundles, curving slightly towards the centre of the stem in the spaces between the bundles. It is more prominent in the stem when very young, as the cells are then filled with starch granules. This layer of cells will be readily seen in sections treated with iodine. ”

“ Thus in the cœlenterates, as seen in Hydra, the muscular layer arises directly from a modification of the surface epithelial cells; and right up to the annelids, even to the highest form in the Polychæta, we still see it stated that the musculature, both circular and longitudinal, arises from the ectoderm. In the Oligochæta and Hirudinea, according to Bergh, there are five rows of teloblasts on each side, of which four are ectodermic and give rise to the nerve-ganglia and the circular muscles, while one is mesoblastic and forms the nephridial organs and the longitudinal muscles. ”

“ His last‐ditch idea was to find a patient with a blood type of AB positive and introduce a small quantity of the special Beta telomerase enzyme into them. The theory was that this might induce their body to produce compatible antibodies, which could then be extracted and cultured in the laboratory. If a sufficient quantity could be produced they could be injected into Bartlett and hopefully arrest the enzyme's pattern of entering the host's bloodstream and metastasizing into the more complex form that brought on the Syndrome. ”

“ In the case of those processes which contain no corpuscles the greater part of their protoplasm seems to be converted into the protoplasm of the spindle-shaped cells. The nuclei arrange themselves so as completely to surround the exterior of the protoplasmic processes. In this way each process becomes converted into a hollow tube, completely closed in by cells formed from the investment of the original nuclei by the protoplasm which previously formed the solid processes. The remainder of the protoplasm probably becomes fluid, and afterwards forms the plasma in which the corpuscles float. ”

“ However, we've found that by isolating and inserting an active copy of the telomerase enzyme into adult stem cells, which can be found in minute quantities throughout the body, we can set their clock back to zero. We extract cells, 'immortalize' them with telomerase, and then return them to the body as a youthful infusion. ”

“ In Raja, the similarity of the pseudo-epithelium to the subjacent tissue is very much more marked than in Scyllium. The pseudo-epithelium appears merely as the superficial layer of the ovarian tunic somewhat modified by its position on the surface. It is formed of columnar cells with vertically arranged fibres which pass into the subjacent layers, and chiefly differ from the ordinary fibres in that they still form parts of the cell-protoplasm enclosing the nucleus. In Pl. 25, fig. 34, an attempt is made to represent the relations of the pseudo-epithelium to the subjacent tissue in Raja. ”

“ New growths, to Hunter, depended on an exudation of the plasma of the blood, in which, by virtue of its own plasticity, vessels formed, and conditioned the further progress. The influence of these ideas seems to have still acted, even after a conception of the cell was arrived at. For starting element, Schleiden required an intracellular plasma, and Schwann a structureless exudation, in which minute granules, if not indeed already pre-existent, formed, and by aggregation grew into nuclei, round which singly the production of a membrane at length enclosed a cell. ”

“ After the curious fusion with another similar protoplast, which constitutes what we call fertilization, the next stage in complexity already noted may be observed, the protoplasm becoming clothed by a cell-membrane. Very soon the single cell gives rise to a chain of cells, and this in turn to a cell mass, the individual units of which are at first quite uniform. With increase of number, however, and consequently enlargement of bulk in the colony, differentiation becomes compulsory. ”