| igm memory: long lived hapten-specific memory in the newt, notophthalmus viridescens. | | 1983 | 6822407 |
| levels of cyclic gmp and cyclic amp in regenerating forelimbs of adult newts following denervation. | the effect of short-term denervation (0, 12, 24, and 72 hours) on the levels of cyclic 3'5'-guanosine monophosphate (cgmp) and cyclic 3'5'-adenosine monophosphate (camp) in adult newt (notophthalmus viridescens) forelimbs at 15, 22, and 35 days of regeneration was investigated. regenerate blastema and stump cyclic nucleotide levels were compared with those of the contralateral intact forelimb and hindlimb, with levels in the normally regenerating blastema, and with levels measured in the forelim ... | 1983 | 6300281 |
| hapten, carrier recognition and response by immunocytes of the primitive vertebrate, notophthalmus viridescens. | these experiments were designed to test whether newt (notophthalmus viridescens) immunocytes are able to recognize the hapten, 2,4,6-trinitrophenyl (tnp), separately from a heterologous erythrocyte (rbc) carrier. while a single priming injection with an erythrocyte species which is unrelated to the carrier of the tnp fails to stimulate amplification of the anti-tnp response, sequential (2x) priming provides about 50% as much amplification as a single priming injection of rbc homologous with the ... | 1983 | 6840813 |
| regeneration of skeletal muscle in notophthalmus viridescens. | | 1983 | 6828513 |
| activation and partial characterization of prolyl hydroxylase from regenerating limbs of the adult newt notophthalmus viridescens. | prolyl hydroxylase activity extracted from regenerating newt (notophthalmus viridescens) limb tissues can be increased by brief preincubation with cofactors (ascorbate, alpha-ketoglutarate, fe2+ and o2) prior to assay with [3h]proline-labeled collagen substrate. newt prolyl hydroxylase is optimally active at 30 degrees c, but loses activity rapidly at 37 degrees c. the presence of cofactors or substrate decreases enzyme heat lability. detergents (triton x-100 and octyl glucoside) do not aid enzy ... | 1983 | 6311481 |
| prolyl hydroxylase activity during newt forelimb regeneration. | prolyl hydroxylase activity was measured to obtain insight into changes in collagen metabolism during forelimb regeneration in the adult newt, notophthalmus viridescens. activity increased markedly during the redifferentiative stages, remained elevated during digit formation, and decreased as regeneration neared completion. the greatest activity, seen during early digit formation, represents a 20-fold increase in activity over the level seen in nonregenerating limbs. the profile of enzyme activi ... | 1983 | 6298034 |
| evidence for a chalone control mechanism in the limb regeneration blastema of the newt, notophthalmus viridescens. | the objective of this study was to investigate the possible involvement of chalones in the control of limb regeneration. saline extracts of whole limb, skinned limb, kidney and liver were injected intraperitoneally, followed by 5 x 0 micrograms colchicine per g body weight into newts, notophthalmus viridescens, bearing cone stage limb regenerates on both forelimbs. forty-eight hours post-injection, tissues were fixed and mitotic figures and pyknotic nuclei were counted in limb blastemata, liver ... | 1983 | 6218877 |
| retinal regeneration in the adult newt, notophthalmus viridescens: appearance of neurotransmitter synthesis and the electroretinogram. | the removal or destruction of retina in the adult newt, notophthalmus viridescens, leads to the formation of a new functional retina by metaplasia of the pigment epithelium. in order to understand the physiological and biochemical changes that occur during regeneration, we have examined the time-course of appearance and maturation of the electroretinogram (erg) and correlated it with the synthesis of the neurotransmitters, acetylcholine (ach) and gamma-aminobutyric acid (gaba). in addition, we h ... | 1983 | 6187414 |
| roles of neural peptide substance p and calcium in blastema cell proliferation in the newt notophthalmus viridescens. | | 1983 | 6187024 |
| retinal ganglion cell body response to repeated axotomy in the regenerating visual system on newt (notophthalmus viridescens). | | 1982 | 7140900 |
| studies of mitosis in excised limb regenerates of the newt, notophthalmus viridescens. | subsequent to excision and explantation of the limb blastema into culture medium, there is an abrupt reduction in mitotic index lasting several hours. coincident with the disappearance of mitosis, abnormal mitotic figures (amfs), lacking the condensed chromosomal nature of normal figures, are seen. these persist until normal levels of mitotic activity are restored approximately 6 hr later. the transient loss of mitotic activity is observed in both ganglionated and nonganglionated explants. the l ... | 1982 | 7142941 |
| pattern regulation between hind- and forelimbs after blastema exchanges and skin grafts in notophthalmus viridescens. | experiments were performed to ascertain whether cells from the forelimb and the hindlimb of newts share a common pattern-regulating mechanism during regeneration. in one series of experiments early digit hindlimb and forelimb blastemas were exchanged either ipsilaterally or contralaterally. in a second experimental series, a strip of forelimb skin was added to a slit in a homologous site on the hindlimb or in a site 180 degrees removed from the position of origin, and vice versa (hindlimb skin i ... | 1982 | 6752335 |
| cyclophosphamide-induced leukopenia and suppression of limb regeneration in the adult newt, notophthalmus viridescens. | cyclophosphamide (cytoxan), a clinical immunosuppressant, produced a marked, persistent leukopenia (greater than 40% reduction) in adult newts in contrast to a transient, milder leukopenia accompanying amputations without cytoxan treatments. in addition, cytoxan suppressed the formation of regeneration blastemata initially: however, blastema formation occurred if a second amputation was performed two or more weeks following the cessation of cytoxan treatments. the failure of the leukopenias of t ... | 1982 | 7130931 |
| cellular proliferation in the skin of x-rayed newt limbs (with a note on x-ray-induced limb regression). | left hind limbs, including the pelvis, of adult newts (notophthalmus viridescens) were locally irradiated with a dose of x-rays that inhibited regeneration (2,000 r). this x-ray dose and other doses (700-2,000 r) capable of inhibiting limb regeneration also cause limb regression prior to amputation. before limb regression occurred, there was a latent period of 3 to 6 weeks. limb regression was characterized by necrotic wasting and resorption of distal elements. the degree of loss was variable an ... | 1982 | 7108473 |
| on the interaction of thyroxine and of oxytocin with prolactin on the growth of the tail fin in the red-spotted newt. | | 1982 | 7106549 |
| effects of trh, tsh, and prolactin on the release in vitro of thyroxine from thyroid glands of the red-spotted newt. | | 1982 | 6809525 |
| cyclic nucleotide metabolism during amphibian forelimb regeneration : ii. the protein kinases. | the hypothesis that camp mediates neural and endocrine influences on limb regeneration was examined by studying the protein kinases in regenerating limb tissues. since these enzymes are the vehicles through which camp acts intracellularly, an understanding of changes in their concentrations and behaviors during regeneration can be instrumental in elucidating the role of camp in this process. mean activities oscillated throughout regeneration with maximal activities being observed during the mid- ... | 1982 | 28305379 |
| comparison of lens regeneration in adult newts, triturus viridescens, between light and dark preadapted and non-preadapted animals. | it is well known that if the original lens is removed from the eyeball in certain urodeles, a new lens will regenerate from the dorsal iris. experiments were designed to study the different effects on lens regeneration in the newt, triturus viridescens, between the light and dark preadapted animals and light and dark non-preadapted animals. the preadapted animals were preadapted to continuous light or dark for 90 days prior to lentectomy. the newts remained in the same controlled environments po ... | 1982 | 7072994 |
| alpha-, beta- and gamma-crystallins in the regenerating lens of notophthalmus viridescens. | | 1982 | 7042379 |
| lens regeneration from the pupillary margin of the eyecup in newt embryos. | early stages in lens regeneration from the dorsal margin of the pupil, following removal of the young lens from the embryonic eyecup, were studied with transmission electron microscopy in notophthalmus viridescens. at the stage of operation, the eyecup cells have an undifferentiated, embryonic appearance with numerous free ribosomes and scattered mitochondria. in normal embryonic eyes containing a lens, the iris epithelium differentiates from the edge of the optic cup by growth and flattening of ... | 1982 | 7058772 |
| dedifferentiation of iris epithelium during lens regeneration in newt larvae. | early stages in lens regeneration from the pigmented epithelium of the dorsal iris were studied in larval notophthalmus viridescens by means of transmission electron microscopy. normal iris epithelium is composed of two layers of low cuboidal cells. packed with melanosomes and surrounded by a basal lamina. scattered desmosomes attach adjacent cells. following lens removal, the intercellular spaces enlarge and the epithelial cells increase in size. some irregular microvilli from these cells exten ... | 1982 | 7058771 |
| 5s ribosomal rna genes of the newt notophthalmus viridescens. | the genes which code for the 5s ribosomal rna in the newt, notophthalmus viridescens have been cloned and analyzed. two types of repeating unit were detected: a major type consisting of a 120 bp coding region with a 111 bp spacer, and a minor type composed of a coding region, a pseudogene, and a 113 bp spacer. the pseudogene is a 36 bp segment which corresponds to the 3' terminal third of the 5s rna gene, and is situated immediately 3' to the gene, being separated from it by 2 bp. two recombinan ... | 1981 | 6275363 |
| ontogeny and localization of the alpha, beta, and gamma crystallins in newt eye lens development. | the alpha-, beta-, and gamma-crystallins, proteins characteristic for the vertebrate eye lens, have been localized in the developing lens of notophthalmus viridescens, the eastern spotted newt. using the immunofluorescence technique, antibodies to the alpha-, beta-, and gamma-crystallin classes were applied to tissue sections through the eye region of developing n. viridescens embryos, harrison (external) stages 30 to 46+. beta-crystallins were the first of the crystallins to appear in a few cel ... | 1981 | 20737883 |
| studies of digit regeneration and their implications for theories of development and evolution of vertebrate limbs. | simple amputation of various combinations of hindlimb digits of notophthalmus viridescens resulted in a variety of abnormal regenerates. the abnormalities included the formation of adventitious digits and branched digits, fusion between digits, and increases and decreases in the normal number of phalanges. the type of abnormality was correlated with the proximal-distal level of amputation and with the identity of the digits removed. these results are discussed in the context of a model for norma ... | 1981 | 7276894 |
| histone gene clusters of the newt notophthalmus are separated by long tracts of satellite dna. | the genomic organization of the histone genes of the newt notophthalmus viridescens is described. genes for the five proteins are clustered on a 9.0 kb segment of cloned dna which is part of a homogeneous family of sequences containing 600--800 members per haploid genome. the 9.0 kb histone gene clusters are not adjacent in the genome, but are separated from neighboring clusters by up to 50 kb or more of cluster spacer sequences; some or all of these spacer sequences are members of a predominant ... | 1981 | 7249077 |
| histone genes are located at the sphere loci of newt lampbrush chromosomes. | in situ hybridization experiments on mitotic and lampbrush chromosomes show that histone genes and an associated 222 bp repeated sequence, satellite 1, are located at or near the sphere loci of chromosomes 2 and 6 of the newt notophthalmus viridescens. during the lampbrush chromosome stage, transcripts of the histone genes and of satellite 1 occur on loops associated with the spheres. histones genes are located at sites on the mitotic chromosomes of triturus cristatus and t. alpestris which are ... | 1981 | 7327042 |
| hyperpigmented patches in the skin of the newt notophthalmus viridescens. | in the integument of the red-spotted newt there occasionally appear patches of skin which are at the same time melanistic and iridescent. such hyperpigmented patches have been found on the back, on the tail and on the dorsal surface of both fore and hind limbs. cytological examination of several such areas revealed the presence of large numbers of chromatophores distributed throughout the dermis. the majority of the chromatophores consisted of atypically large and dendritic melanophores, which c ... | 1981 | 7314076 |
| hapten-specific, carrier dependent cells in the newt, notophthalmus viridescens. | | 1981 | 6974108 |
| ultrastructural studies on migrating epidermal cells during the wound healing stage of regeneration in the adult newt, notophthalmus viridescens. | the ultrastructure of the epidermal cells which migrate over the wound surface of the amputated limb of the adult newt, notophthalmus viridescens, was observed with transmission (tem) and scanning (sem) electron microscopy. in order to aid in the visualization of polyanionic surface materials on the wound epithelium and wound surface with tem, the basic dye, ruthenium red, was introduced into the fixatives and buffer. control limbs were processed without ruthenium red. shortly after amputation, ... | 1980 | 6160761 |
| iodine metabolism in the red-spotted newt studied with radioactive tracer and by radioimmunoassay. | | 1980 | 7409466 |
| cyclic nucleotide metabolism during amphibian forelimb regeneration : i. the cyclic amp phosphodiesterases. | concentrations of the cyclic nucleotides in regenerating limb tissues change in a manner which suggests that they might mediate neural or endocrine influences upon specific developmental events. since modulation of the role of camp within this process can be achieved through camp phosphodiesterase, enzymatic activity, relative intracellular distribution, and the kinetic parameters of this enzyme were examined at several stages of limb regeneration in adultnotophthalmus viridescens. both forms of ... | 1980 | 28304959 |
| fine structure of the surfaces of the epithelium and mesenchyme of the newt limb regenerate, separated in salt solution: 14 to 25 days. | forelimbs of the newt notophthalmus (triturus) viridescens were amputated at the wrist, and at 14 to 25 days, the new limb regenerates were removed by a razor-blade cut. after incubation of the isolated regenerates in a medium containing only inorganic salts, the epithelium was removed easily from the underlying mesenchyme. the surfaces separated in the salt solution were examined using scanning and transmission electron microscopy to evaluate the completeness of the separation and the extent of ... | 1980 | 7416054 |
| increased activities of acid protease and acid phosphatase in denervated forelimb regenerates of the adult newt, notophthalmus viridescens. | early bud and palette limb regenerates of the adult newt, notophthalmus viridescens, were compared with respect to the effect of denervation on the activities of some of their hydrolases in order to determine if these enzymes contribute to the atrophy of denervated regenerates. results show that denervation increased total activities of acid protease and acid phosphatase by 77-89% and 41-45% respectively at both stages examined. both membrane-bound and soluble enzymatic forms contributed to the ... | 1980 | 7002737 |
| crystallin expression in the tvi cell line. | the tvi cell line, derived from dorsal iris cells of adult newts (notophthalmus viridescens), was investigated for the presence of crystallins. since there is reason to believe that iris epithelial cells are the main sources of this cell line and since iris epithelial cells are known to convert into lens cells in primary cultures, it is possible that tvi cells also possess the capacity to synthesize crystallins, those proteins characteristic of lens cells. it is also possible, however, that the ... | 1980 | 7000607 |
| effect of apical epidermal cap on mitotic cycle and cartilage differentiation in regeneration blastemata in the newt, notophthalmus viridescens. | | 1980 | 7372003 |
| the effect of prolonged light and dark adaptation on lens regeneration in the adult newt triturus viridescens. | light intensity has been shown to affect lens regeneration in adult newts. experiments were designed to study the effects of different light controlled environments on lens regeneration in the newt t, viridescens. animals were preadapted to three light conditions: control, light from below and dark for ninety (90) days prior to lentectomy. the newts remained in the controlled environments post-lentectomy to test the effects of light preadaptation on lens regeneration. the results indicate that c ... | 1980 | 7380324 |
| limb regeneration of the adult newt (notophthalmus viridescens) in the absence of the spleen. | it has been suggested that the immune system might figure prominently in the regulation of forelimb regeneration. however, neither the nature of this influence nor the aspect(s) of regeneration influenced are clearly known. the determination of which components of the immune system are indispensable for regeneration would be a logical first step in attempting to address such questions. this investigation, therefore, examined the effects of removing the spleen, a major lymphoid organ in the newt, ... | 1980 | 28305929 |
| effect of testosterone and 17-beta estradiol on limb regeneration in the newt, notophthalmus viridescens. | gonadectomy, or injections of testosterone or 17-beta estradiol, had no apparent effect on the rate of regeneration or histological appearance of limb regenerates in the newt, notophthalmus viridescens. neither promotion, nor inhibition of limb regeneration was observed. | 1979 | 520495 |
| retinal ganglion cell response to axotomy and nerve growth factor antiserum in the regenerating visual system of the newt (notophthalmus viridescens): an ultrastructural morphometric analysis. | one 3.0 mg dose of the nerve growth factor antiserum (anti-ngf) injected into the vitreous chamber of the eye at the time of optic nerve transection elicits significant changes in the normal newt (notophthalmus viridescens) retinal ganglion cell body response to axotomy at 7 and 14 days postaxotomy (dpa). light microscopic observations indicate that anti-ngf treatment significantly reduces the per cent of retinal ganglion cells demonstrating nuclear chromatin reactivity (ie., homogeneous to a mo ... | 1979 | 497824 |
| lizard and newt tail regeneration: a quantitative study. | almost perfect fits of the gompertz equation to the growth in length of tail regenerates in the lizard, lacerta lepida, and the newt, notophthalmus viridescens, were obtained. comparison of certain parameters of the equation with published mitotic index data suggests that the gompertz equation characterizes each system at least from the time that significant mitotic activity is first observed histologically. an objective method for comparing the regeneration periods of the two species is describ ... | 1979 | 536712 |
| effects of x-rays on nerve-dependent (limb) and nerve-independent (jaw) regeneration in the adult newt, notophthalmus viridescens. | the newt limb requires nerves for successful regeneration, but the jaw appears to be nerve independent. among the current hypotheses for the regeneration-inhibitory action of x-rays is one proposing inactivation of nerves as the main cause. we decided to test this hypothesis by comparing the irradiation levels necessary for inhibition of limb and jaw regeneration. jaws and left front limbs were exposed locally to doses of ionizing x-irradiation ranging from 250 to 2000 r at least 6 weeks prior t ... | 1979 | 536692 |
| separation of the epithelial and mesenchymal components of the newt limb regenerate with salt. | after incubation of isolated forelimb regenerates of notophthalmus (triturus) viridescens at all developmental stages for 60 minutes at 37 degrees c in a salt medium containing 111 mm sodium chloride, 5.6 mm potassium chloride and 100 mm sodium phosphate buffer at ph 7.5, the wound epithelium of each regenerate was removed intact from its underlying mesenchymal component. the suggestion is made that the salt medium is an effective epithelial-mesenchymal separating agent due to a combination of i ... | 1979 | 490137 |
| retinal ganglion cell response to axotomy and nerve growth factor in the regenerating visual system of the newt (notophthalmus viridescens): an ultrastructural morphometric analysis. | nerve growth factor (ngf) treatment, given as a single 200 bu intraocular injection at the time of optic nerve transection, was found to significantly accelerate the retinal ganglion cell response to axotomy in the newt (notophthalmus viridescens). in the control series the per cent of neurons in the retinal ganglion layer demonstrating nuclear reactivity (i.e. chromatin changes) reaches a peak by 14 days post axotomy (14 dpa), plateaus through 21 dpa and falls thereafter, returning to control l ... | 1979 | 466440 |
| autoradiographic and electron microscopic studies of minced cardiac muscle regeneration in the adult newt, notophthalmus viridescens. | the regenerative response of minced cardiac muscle grafts in the adult newt was studied using autoradiography and electron microscopy. one-sixteenth to one-eighth of the newt ventricle was amputated, minced, and returned to the wounded ventricle. at five days after grafting, no reorganization of graft msucle pieces was apparent and there was degeneration of much of the muscle graft. another, smaller population of 5-day myocytes had euchromatic nuclei and intact sarcolemmae. in 10- and 16-day gra ... | 1979 | 469482 |
| effects of parathyroidectomy and of parathyroid extract on levels of calcium and phosphate in the blood and urine of the red-spotted newt. | | 1979 | 456879 |
| the occurrence of a tetrodotoxin-like substance in the red-spotted newt, notophthalmus viridescens. | | 1979 | 442108 |
| effective population size and interdemic migration rates in a metapopulation of the red-spotted newt, notophthalmus viridescens (rafinesque). | | 1978 | 28567923 |
| rna transcription on the giant lateral loops of the lampbrush chromosomes of the american newt notophthalmus viridescens. | by counting silver grains in autoradiographs of lampbush chromosomes the rates of incorporation of [3h]adenine, [3h]cytidine, [3h]guanosine and [3h]uridine, administered separately, into rna on the giant loops of chromosome ii of notophthalmus viridescens, were compared with the rates of incorporation of these same precursors into rna on other, unidentified loops. the overall rate of rna transcription on the giant loops is only about half that on the generality of other loops, and the rna transc ... | 1978 | 748343 |
| retinal ganglion cell response to axotomy in the regenerating visual system of the newt (triturus viridescens): an ultrastructural morphometric analysis. | | 1978 | 729683 |
| a scanning electron microscopic and quantitative histologic description of lens regeneration in the newt, notophthalmus viridescens. | | 1978 | 722789 |
| occurrence of trypanosomiasis in the red eft stage of the red-spotted newt, notophthalmus viridescens (rafinesque). | | 1978 | 722463 |
| the jelly envelopes and fertilization of eggs of the newt, notophthalmus viridescens. | fertilization in notophthalmus viridescens is internal and involves passage of the sperm through five layers of egg jelly (j5-j1, from outermost to innermost), each of which is secreted by a discrete region of the oviduct. polyspermy is normal. passage of the sperm through the jelly and into the egg was studied by a technique of artificial insemination similar to natural insemination, in that undiluted fluid from the vas deferens was applied directly to eggs with various layers of jelly present, ... | 1978 | 569209 |
| effect of amputation and limb regeneration on the pars distalis of the newt, notophthalmus viridescens. | a study of the pituitary of the newt, notophthalmus viridescens, during limb regeneration indicated no observable changes in histology or ultrastructure of any of the cells of the pars distalis when compared with the pars distalis of unamputated control newts. | 1978 | 720526 |
| re-regeneration of lower jaws and the dental lamina in adult urodeles. | transverse amputations were carried out through one-third fully regenerated jaw segments and through normal tissue of the mandible on the same and opposite sides of the jaw in adults of notophthalmus viridescens. collectively the results suggest that, in adult urodeles, the mandible and the dental lamina can be replaced in an identical manner more than one time. although the major histological events are the same in jaw regeneration and re-regeneration, regrowth is more rapid in re-regeneration. ... | 1978 | 702533 |
| testosterone and 5alpha-dihydrotestosterone inhibit both growth and spermatogenesis in the remaining testis in partially castrated adult newts, notophthalmus viridescens. | the testis of the newt, notophthalmus viridescens, undergoes hypertrophy following partial castration. injections of either testosterone or 5alpha-dihydrotestosterone are equally effective in inhibiting the increase in testis weight which follows partial castration. in addition, both of these androgens inhibit spermatogenesis, i.e., spermatogonia appear to be inhibited resulting in early cessation of spermatogenesis and a precocious division of the testis into separate spermatogonia and sperm co ... | 1978 | 702083 |
| neural and hormonal stimulation of dna and protein synthesis in cultured regeneration blastemata in the newt notophthalmus viridescens. | | 1978 | 680355 |
| the morphology of the mucous gland and its responses to prolactin in the skin of the red-spotted newt. | the mucous gland of the red-spotted newt, notophthalamus viridescens viridescens, rafinesque was examined by histochemical and ultrastructural techniques and its cytological responses to various hormonal conditions were studied. its secretory epithelial cells produce and release in merocrine fashion a neutral, unsulphated mucosubstance. the secretory epithelium is bounded peripherally by a thin, but apparent non-functional, myoepithelium. the duct of this mucous gland consists of a single kerati ... | 1978 | 671558 |
| regenerative ability of double-half and half upper arms in the newt, notophthalmus viridescens. | the upper arms of adult newts (notophthalmus viridescens) were surgically manipulated to create double-half dorsal, double-half ventral, double-half anterior, and double-half posterior upper arms, and longitudinal half-dorsal, half-ventral, half-anterior, and half-posterior upper arms. amputation through the double-half upper arms usually failed to elicit normal distal regeneration, despite the fact that an apparently normal regeneration blastema was initially formed. instead, regeneration in th ... | 1978 | 660137 |
| scanning electron microscopy of epidermal cell migration in wound healing during limb regeneration in the adult newt, notophthalmus viridescens. | the epidermal cells which migrate over the wound surface of the amputated limb of the adult newt were examined using the scanning electron microscope. specimens were prepared routinely for scanning electron microscopy or were embedded in epon 812 for light microscopic observations. a cuff of epidermal cells was seen at the edge of the wound, from which cells appeared to migrate over the wound surface. as early as five hours after transection of the limb, the basal layers of this cuff appeared to ... | 1978 | 645617 |
| glial reaction to nerve growth factor in the regenerating optic nerve of the newt (triturus viridescens). | | 1978 | 639915 |
| repair and reorganization of minced cardiac muscle in the adult newt (notophthalmus viridescens). | | 1978 | 633377 |
| morphological changes in the ultrastructure of the thyroid epithelium of notophthalmus viridescens after hypophysectomy and tsh- and prolactin stimulation. | in the newt, notophthalmus viridescens, hypophysectomy results in progressive atrophy of the thyroid cells to the point of irreversible degeneration. after exclusive tsh-stimulation of hypophysectomized newts, increased endocytotic activity of the follicular epithelium is observed. prolactin stimulation under the same conditions prevents atrophy but does not result in increased cell activity, as expressed by the reduced amount of microvilli and the lack of endocytotic activity. combined tsh- and ... | 1978 | 630599 |
| regenerative repair in the severed optic nerve of the newt (triturus viridescens): effect of nerve growth factor antiserum. | | 1978 | 620705 |
| regenerative repair in the severed optic nerve of the newt (triturus viridescens): effect of nerve growth factor. | | 1977 | 923673 |
| intercalary and supernumerary regeneration in regenerating the mature limbs of notophthalmus viridescens. | | 1977 | 925660 |
| hormonal regulation of cellular proliferation in the epidermis of the red-spotted newt. | | 1977 | 198340 |
| hormonal effects on mitotic rhythm in the epidermis of the red-spotted newt. | | 1977 | 198339 |
| accumulation of glucocorticoids in regenerating areas of limbs of the newt, notophthalmus viridescens. | evidence is presented that regenerating portions of newt limbs preferentially accumulate 3h-labelled exogeneous cortisol and corticosterone. the ability of such regions to accumulate glucocorticoids is maximal about seven days after amputation and is abolished by interrupting the spinal nerves innervating the limb. either hypophysectomy or ablation of interrenal tissue is without marked effect. the accumulation effect is not shown by aldosterone, testosterone, glucose, cholesterol, or leucine bu ... | 1977 | 886293 |
| influence of indomethacin on lens regeneration in the newt notophthalmus viridescens. | following lentectomy newts were injected with indomethacin in a variety of carrier solutions at doses ranging from 1.2-120 mg/kg body weight every other day for 15-17 days. the results show that injection of this drug according to the regimen used has no significant effect on regeneration of the lens. the data suggest, but do not prove, that prostaglandins may not play a major role in the early phases of lens regeneration in the newt. | 1977 | 28304907 |
| the protective action of zinc against the deleterious effects of cadmium in the regenerating forelimb of the adult newt, notophthalmus viridescens. | forelimbs of adult male newts (notophthalmus viridescens) were amputated and immediately dipped in cadmium nitrate for 2 minutes; in addition, some of the newts were injected with zinc chloride 24 hours prior to, or 24 hours after amputation. dipping the amputated forelimb of a newt in a solution of 0.4 m cadmium nitrate completely inhibited or retarded regeneration throughout the 65 days of observation. other effects of cadmium administration included erythema of the limb, an extensive protrusi ... | 1977 | 892583 |
| pituitary enhancement of wolffian lens regeneration in vitro: spatial and temporal requirements. | when irido-corneal complexes (icc's) from eyes of adult newts (notophthalmus viridescens) are cultured on top of pituitary glands they produce advanced lens regenerates in up to 90% of the cases (this report and connelly et al., '73). to determine if the iris and pituitary gland must be in direct contact with each other in order to produce this enhancement of lens regeneration, icc's were cultured next to pituitary glands or separated from them by a nuclepore filter. cultures behaved as icc's cu ... | 1977 | 874445 |
| repolarization of reversed, regenerating lenses in adult newts, notophthalmus viridescens. | | 1977 | 862682 |
| inversion heterozygosity in females of the newt notophthalmus viridescens and its influence on chiasma distribution. | in a wild population of the american newt notophthalmus viridescens 15 females out of a total of 94 were found to be heterozygous for a paracentric inversion which includes almost the whole of the longer arm of the smallest chromosome (xi). the inversion was recognized in preparations of lampbrush chromosomes because it transfers the sequential loops, which normally lie close to the telomere, to a position neighbouring the centromere. because of inversion the transcriptional polarity of the sequ ... | 1977 | 893540 |
| transfilter mitogenic effect of dorsal root ganglia on cultured regeneration blastemata, in the newt, notophthalmus viridescens. | | 1977 | 849801 |
| changes in cyclic gmp levels during forelimb regeneration in adult notophthalmus viridescens. | cyclic 3', 5'-guanosine monophosphate (cgmp) was measured at eight stages of forelimb regeneration in adult newts and compared with the cgmp levels of non-regenerating control limbs. there was a significant increase in cgmp content during dedifferentiation followed by a sharp decrease to minimal levels at the cone stage. a second smaller increase in cgmp occurred between the cone stage and mid-differentiation, followed by a decrease to relatively constant levels approaching control values as dif ... | 1977 | 192831 |
| the early stages of wallerian degeneration in the severed optic nerve of the newt (triturus viridescens). | the initiation of wallerian degeneration in the severed optic nerve of the newt (triturus viridescens) was very rapid and intense. significant degeneration of nonmyelinated axons was observed as early as six hours after lesion (h.a.l.) and was almost complete by 48 h.a.l. initial degeneration of non-myelinated axons began in "extracellular digestion chambers" formed between burgeoning ependymoglial processes. the remaining fragments and debris were later phagocytized by surrounding ependymoglial ... | 1977 | 851236 |
| water balance responses to dehydration and neurohypophysial peptides in the salamander, notophthalmus viridescens. | | 1977 | 844677 |
| the relationship between growth, developmental stage and postamputation age of the regeneration blasterma of the newt, notophthalmus viridescens. | the growth of the regeneration blastema of the newt forelimb has been quantitated and analyzed as a function of postamputation age, developmental stage, animal weight, animal length, and cross sectional diameter of the blastemal base in both the anteroposterior and dorsoventral dimensions. correlation coefficients computed for these variables show that growth of the regenerate in both length and volume is more closely correlated with developmental stage than postamputation age. in addition, the ... | 1977 | 839186 |
| regenerative failure of double half limbs in notophthalmus viridescens. | | 1976 | 980112 |
| on the identity of the thyrotropic cell in the red-spotted newt. | although the pars distalis of the red-spotted newt has previously undergone extensive cytological examination, the identity of its thyrotropic cells has remained uncertain. from the present ultrastructural study, cells of type 3 (masur, 1969) containing granules 150-180 nm in diameter are concluded to be the thyrotropes. such cells were found to be present in the regions of the pars distalis where thyroidectomy cells arise after ablation of the thyroid gland. cells of type 3 are probably identic ... | 1976 | 825228 |
| fine structure of active ribosomal genes. | the structure of active ribosomal genes in the newt notophthalmus viridescens has been studied at the higher resolution permitted by negative staining. spherical particles, 70 a to 100 a in diameter are seen on the non-transcribing "spacer" regions, but were absent from certain regions of the transcribing "matrix". the matrix core often appears thicker than a double strand of dna. these results are discussed in the light of the recently discovered subunit structure of chromatin, and in relation ... | 1976 | 1001149 |
| muscle satellite cells in urodele amphibians: faciliatated identification of satellite cells using ruthenium red staining. | the ruthenium red (rr) stained forelimb musculature of three species of urodeles triturus (notophthalmus) viridescens, amblystoma maculatum, amblystoma opacum in various stages of growth were examined with the electron microscope for the presence of satellite cells. it was found that rr staining facilitated greatly the identification of satellite cells. in young larvae of all three species satellite cells were detected with a frequency of 29% to 48% per total number of nuclei. in adult triturus ... | 1976 | 978162 |
| an established cell line from the newt notophthalmus viridescens. | an established cell line, derived from the dorsal iris of the eastern north american newt, notophthalmus viridescens, is described. the cells display an epithelial-like behaviour in culture, grow relatively slowly, possess considerably larger chromosomes than mammals and are heteroploid, although some near-diploid cells are present in the culture. the line is characterized by a strong tendency to overlapping and aggregation in spite of its origin from adult tissue. | 1976 | 1010157 |
| a light and electron microscopic investigation of the hepatic parenchyma of the adult newt, notophthalmus viridescens. | this light and electron microscopic study demonstrates that the liver of the adult newt, notophthalmus viridescens, consists of a mass of hepatocytes interrupted by blood sinusoids which allow blood to percolate through the parenchyma. the plates separating adjacent sinusoids are usually two or more cells thick and the bile canaliculi lie between 2-6 neighboring cells. fine structural characteristics of hepatocytes include abundant lipid and glycogen inclusions. melanophores with developing mela ... | 1976 | 937737 |
| collagen metabolism in the regenerating forelimb of notophthalmus viridescens: synthesis, accumulation, and maturation. | | 1976 | 1278591 |
| dose-dependent effects of methylmercury on limb regeneration of newts (triturus viridescens). | | 1976 | 949962 |
| regeneration from different levels along the tail of the newt, notophthalmus viridescens. | some aspects of the influence of position on regeneration have been examined by comparing regeneration from different levels along the newt tail. tails amputated such that either three-fourths one-half or one-fourth of the tail was removed pass through the same morphological and histological stages at the same times after amputation. in tails amputated at these three different levels, the rate of elongation of regenerates from more proximal levels is greater than that of regenerates from more di ... | 1976 | 932661 |
| stages of tail regeneration in the adult newt, notophthalmus viridescens. | five distinguishable stages of tail regeneration in the adult newt have been established. the stages are based on external morphological changes and internal histological characteristics rather than chronological age of the regenerate. | 1976 | 932660 |
| regenerative abnormalities in notophthalmus viridescens induced by repeated amputations. | the fidelity of the regenerative response in the adult newt, notophthalmus viridescens, was examined following repeated amputations at the level of the distal one-third of humerus. three to four months following amputation, all regenerates were scored for gross morphology, reamputated, and stained with methylene blue for skeletal elements. the occurrence of abnormal regeneration with respect both to gross morphology and to skeletal structure was found to increase directly with the number of time ... | 1976 | 1271038 |
| supernumerary limgs in amphibians: experimental production in notophthalmus viridescens and a new interpretation of their formation. | | 1976 | 1269829 |
| the mitotic chromosomes of notophthalmus (=triturus) viridescens: localization of c banding regions and dna sequences complementary to 18s, 28s and 5s ribosomal rna. | the metaphase chromosomes of notophthalmus (triturus) viridescens have been studied by c-banding and in situ hybridization. the chromosomes show the pericentric c-banding seen in many organisms and in addition have interstitial c-bands located a short distance from the pericentric c-bands on each chromosome arm. a few c-bands are seen in telomeric regions. regions which hybridize in situ with 18s and 28s ribosomal rna were found on three chromosome pairs. the animals studied fell into three grou ... | 1975 | 1201683 |
| an autoradiographic study of the origin of intestinal blastemal cells in the newt, notophthalmus viridescens. | | 1975 | 1204929 |
| morphogenesis of the carpal elements in the regenerating forelimb of adult notophthalmus viridescens viridescens. | this study is concerned with the morphogenesis of the carpal elements in the regenerating forelimb of the adult newt. blastema cells surrounding the remnant bony stumps begin to differentiate into cartilage on the twentieth post-amputation day. subsequently, masses of carilage build up from the radial and ulnar stumps. the radial mass is larger and differentiates more rapidly than the ulnar mass. by the fifty-fifth post-amputation day, the eight basic carpal elements are formed, with fusion of t ... | 1975 | 1200330 |
| disruption of normal forelimb regeneration in adult notophthalmus viridescens by sublethal concentrations of trypan blue. | the effects of the vital dye trypan blue (tpb) on the regeneration of amputated newt forelimbs were examined. administration of the dye (10 mug/g body weight) via ip injection during the early wound healing and dedifferentiation phases of regeneration inhibited the normal regenerative response. the accumulation phases of regeneration are similarly halted but only by greater concentrations of tpb (50 mug/g body weight) while redifferentiation and morphogenesis are only affected by still greater c ... | 1975 | 1194876 |
| progesterone-induced in vitro maturation in oocytes of notophthalmus viridescens (amphibia urodela) and some observations on cytological aspects of maturation. | maturation in vitro of oocytes of the newt, notophthalmus viridescens, is inducible with progesterone after in vivo treatment of females with gonadotropin; few oocytes mature in vitro in the absence of such gonadotropin treatment. chromosomes of most large oocytes of animals not receiving gonadotropin are still in the lampbrush condition; chromosomes from gonadotropin-treated animals are shorter and the lateral loops are less profuse and somewhat retracted. the chromosome condition, then, can be ... | 1975 | 1194840 |
| the developmental cytology of the nuptial pad in the red-spotted newt. | | 1975 | 1158027 |
| localization of 5'-ribonucleotide phosphohydrolase in regenerating (and normal) limb tissues of the adult newt notophthalmus viridescens. | the regenerating forelimb of the adult newt, notophthalmus viridescens was investigated for 5'-nucleotidase (5' ribonucleotide phosphohydrolase, 3.1.3.5) acitivity. the newt's humeri were surgically removed, and after a twenty-one-day recovery period, the forelimbs amputated above the elbows. regenerates were sampled at predetermined times for specific phases in the progress of regeneration, frozen, sectioned in a cryostat, and the sections fixed in 10% cold formol calcium. the wachstein and mei ... | 1975 | 241677 |
| non-glial phagocytes within the degenerating optic nerve of the newt (triturus viridescens). | two non-glial phagocytes were found to participate along with ependymoglial cells in wallerian degeneration of the severed optic nerve of the newt (triturus viridescens). the first type of non-glial cell (polymorphonuclear phagocyte) was positively identified as a neutrophil and participates in the early stages of degeneration. cells of this type make a brief appearance, reaching a peak by the second postoperative day (2 p.o.d.), and quickly diminish until few can be found by 4 p.o.d. neutrophil ... | 1975 | 1141845 |
| the effects of hypophysectomy upon the endogenous levels of cyclic amp during forelimb regeneration of adult newts (notophthalmus viridescens). | cyclic amp is believed to play a role in limb regeneration. using high pressure liquid chromatography, endogenous levels of cyclic amp in regenerating tissues of normal and of hypophysectomized adult newts were estimated. in normally regenerating limbs, cyclic amp levels were depressed 7 days after amputation and were elevated at 14 and 21 days. in contrast, limb tissues of hypophysectomized newts displayed elevated cyclic amp levels at 7, 14 and 21 days after amputation. a correlation exists be ... | 1975 | 28304953 |
| a light and electron microscopic study of myelopoietic cells in the perihepatic subcapsular region of the liver in the adult aquatic newt, notophthalmus viridescens. | the liver of the newt, notophthalmus viridescens, consists of several incompletely separated lobes of parenchymal tissue each of which is covered by a perihepatic subcapsular region (ssr) of the myeloid tissue. this tissue contains neutrophils and eosinophils in various stages of differentiation. as neutrophils developfrom myeloblasts to late neutrophilic myelocytes, two types of granules appear. the primary granules (type of granules formed first) are more electron dense and smaller than the se ... | 1975 | 1149091 |