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Results for “regeneration”

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At least 19 recordsLinked to original sources
PubMed1976

[Cytochemical analysis of muscle cell histones of Triturus cristatus limbs a) in normal regeneration, b) in regeneration arrested by r-irradiation, and c) in regeneration restored by implants].

The muscular cells of regenerating limbs and of limbs in which regenerative power is restored, show an important decrease in the amount of cytophotometrically detected histones. This decrease is owing to the arginine rich fraction and to the lysine rich fraction. The muscular cells of irradiated limbs show a decrease in the amount of histones. This decrease is owing only to the arginine rich fraction and continues after the thirieth day of irradiation and amputation.

Animals↗
PubMed1979

Kinetics of the regeneration of sea-urchin cilia. II. Regeneration of animalized cilia.

The kinetics of the regeneration of cilia of Arbacia punctulata animalized by treatment with trypsin have been examined. The cilia regenerate with biphasic kinetics: an initial linear phase which changes abruptly to a second, slower linear rate. Inhibition of protein synthesis with 10 microM emetine has little effect on the first phase but totally abolishes the second, suggesting that the first phase represents the utilization of a pre-existing precursor pool while the second reflects de novo protein synthesis. However, cilia will regenerate again following a second deciliation in the presence of emetine, to half the plateau value of the first regeneration, indicating that only a fraction of the pool of the limiting precursor can be assembled into the regenerating cilium. It is proposed that a residual pool of this precursor is required to maintain the assembly-disassembly equilibrium in favour of the assembled organelle.

Animals↗
PubMed1979

Quantitative studies of the regeneration of rat myelinated nerve fibres: variations in the number and size of regenerating fibres after repeated localized freezings.

The number and size of myelinated nerve fibres were determined in the nerve to the medial head of the gastrocnemius muscles of rats whose left sciatic nerve was repeatedly frozen (one to five times at three weekly intervals). The contralateral nerve was used as a control. Results varied according to the number of freezings performed and, for a given number of freezings, according to the period of regeneration. When measurements were completed 1 month after the last of several localized freezings, the number of regenerating myelinated nerve fibres increased regularly up to the third freezing, reaching to about 220% of the control value, but no higher values were recorded after four or five freezings. The nerve fibre distribution was unimodal in all the nerves studied. The mean diameter of all myelinated fibres decreased with the number of freezings from 50% of the control value after the first to 36% after the fifth. When measurements were made 1, 3, 6, 12 and 18 months after the third and final freezing, the number of regenerating myelinated nerve fibres decreased by about 30% between the first and third month and then stabilized at 190% of the control value. Nerve fibre distribution became bimodal from the third month onwards, and the mean diameter of all myelinated fibres increased regularly. However, by the eighteenth month, the size of regenerated myelinated nerve fibres had only reached 70% of the normal contralateral value.

Animals↗
PubMed1978

[Regeneration of a whole worm from a small fragment of the body of Dugesia tigrina planaria following repeated removal of regenerates].

The ability of restoration of the whole worm from a small body fragment was not reduced after 8 removals of the anterior and posterior regenerates. The polarity of restoring fragments in the most cases corresponded to the initial one. Upon the colchicine effect on the restoring fragments which accompanied the repeated removal of the regenerates, a high percentage of cases of incomplete somatic embryogenesis was observed: the formation of bi- and multipolar forms. The formation of regenerates is realized by neoblasts. Upon the repeated removal of regenerates, the dedifferentiated intestine cells appear to take part in the restorative processes as well.

Animals↗
PubMed1977

Hormone control in regeneration: effects of somatostatin on appendage regeneration, blood glucose and liver glycogen in Diemictylus viridescens.

In the present communication, synthetic somatostatin, a hypothalamic factor which has a known inhibitory effect on the release of growth hormone, thyroid-stimulating hormone, prolactin, insulin and glucagon in man and other mammals, was found to have an inhibitory effect on limb and tail regeneration in adult Diemictylus viridescens, when the newts were treated with a daily dose of 3-5 or 15 microgram/animal for a period of 34 days post-amputation. At the higher dose, the animals exhibited total inhibition of appendage regeneration in a few cases and the remainder showed a considerable delay compared to the controls; none of the experimental animals reached the advanced four-digit stage achieved by the controls. Furthermore, the blood glucose and liver glycogen values in the somatostatin-treated animals were significantly lower than the control values. Mechanisms in the storage, mobilization and utilization of glucose (involving hormones) are discussed in relation to appendage regeneration in the newt and possible controls of regeneration at the level of the hypothalamus are suggested.

Animals↗
PubMed1977

Bioelectricity and regeneration: large currents leave the stumps of regenerating newt limbs.

Electrical currents near regenerating newt limbs were measured with a recently developed vibrating probe. Steady currents with local surface densities of 10 to 100 muA/cm2 or more leave the end of the stump during the first 5-10 days after amputation and are balanced by currents with densities of only 1-3 muA/cm2 that enter the intact skin around the stump. They are immediately dependent upon the entry of sodium ions into this skin and are therefore inferred to be skin-driven. The outward currents are comparable in direction, density, duration, and position to artificially imposed currents previously found sufficient to induce significant regeneration of amputated adult frog limbs. This comparison suggests that the endogenous stump currents play some causal role in initiating regeneration.

Amiloride↗
PubMed1977

[Ultrastructure of the cells and DNA synthesis in skeletal muscle regeneration. A study of the regeneration of the frog sartorius muscle by an electron microscopic autoradiographic method].

The ultrastructure of cells of the regenerating frog's sartorius muscle and their capacity to synthesize DNA was studied by means of 3H-thymidine (3HT) electron microscope autoradiography. On the 8-17th post injury (p.i.) days, 2 hours following 3HT administration, only mononuclear cells were seen labeled, the myotube nuclei incorporating no 3HT. Along with the endothelial cells, fibroblasts, phagocytes and cells identified conventionally as myoblasts, satellite cells examined from both necrotic and viable parts of injured myofibers were labeled. No myoblast sequestration from the injured myofibers occurred. By the 13-15th p.i. days, numerous myoblast-like cells are accumulated beneath the glycocalix layer covering the free ends of myotubes which are rich in ribosomes and display an active sarcomerogenesis. Some of these myoblast-like cells become labeled after 3HT pulse. The 13 day p.i. regenerates examined 72 hours following 3HT injection display labeling in numerous myotube nuclei. This is indicative of the myoblast fusion, which is believed to play a principal role in the regenerative somatic myogenesis. Within the myonuclei adjacent to the areas of the regeneration, membranous and/or fibrillar structures of an unknown origin were frequently observed.

Animals↗
PubMed1977

[Variations in the completeness of skin regeneration during post-traumatic regeneration].

The healing of the full-thickness skin wounds on the abdomen and the back of hedgehogs was investigated. The wound healing on the abdomen proved to result mainly from the wound contraction. In most cases a small regenerated area containing new hair and sebaceous glands was formed in the centre of the wound. Contraction of the wound was practically absent on the back and its healing occurred chiefly by new tissue formation; due to this vast regenerated areas were formed in the wound. Connective tissue frame-work of the regenerated area on the abdomen and the back resembled intact derma by fiber distribution.

Animals↗
PubMed1977

[Eyestalk removal and intensive regeneration: joint effects on the molting cycle of Pachygrapsus marmoratus (Crustacea, Decapoda), variability of the critical regeneration stage].

When eyestalk-removal and pereiopod-removal, followed by intensive regeneration, are realized together on the same animal, their accelerative effect on the moulting rate is lower than the effect of only one of these two processes. The critical stage of pereiopod regeneration varies between the moulting stages C4 to D1 according to the physiological state of the Crab.

Animals↗