[structural characteristics and innervation of chromaffin tissue in the adrenal gland of the axolotl]. | each adrenal gland of the axolotl consists of a strip lying all along the medio-lateral edge on the ventral surface of the kidney. the gland is composed of interrenal cells (ic) and chromaffin cells (cc). the ic contained a great number of pleomorphic lipid droplets, smooth endoplasmic reticulum and elongated mitochondria with tubulo-vesicular cristae. two types of cc, always disposed in clusters and exhibiting long cytoplasmic processes were described according to the electron density, size and ... | 1986 | 3094843 |
glucagon and insulin regulate in vitro hepatic glycogenolysis in the axolotl ambystoma mexicanum via changes in tissue cyclic amp concentration. | glucagon increases the rate of glycogenolysis in in vitro cultures of hepatic tissue from the axolotl ambystoma mexicanum. the hormone causes an increase in the concentration of cyclic amp in the tissue which is followed by activation of glycogen phosphorylase and subsequent breakdown of glycogen and release of glucose from the tissue. insulin counteracts the glycogenolytic effect of glucagon by inhibiting the increase in tissue cyclic amp concentration brought about by glucagon. this inhibitory ... | 1986 | 2416634 |
a quantitative analysis of regeneration from chimaeric limb stumps in the axolotl. | we have analysed the cellular contribution and cellular displacement which occur during regeneration from chimaeric (half triploid, half diploid) lower arms in the axolotl. in general both anterior and posterior halves contribute approximately 50% of the regenerated limb cells. deviations from equal contribution were observed only when anterior tissue was grafted, suggesting that anterior tissue is more sensitive to grafting operations. approximately 25% of all cells in the regenerated limb were ... | 1985 | 3834023 |
molecular duality of dna ligase in axolotl corresponds to distinctive transcriptional information. | based upon the use of specific antibodies and sucrose gradient sedimentation analysis, the present work describes the use of the post-transcriptional equipment of the urodele egg to compare the information contained in two rna samples extracted from respectively liver and activated axolotl eggs. it is shown that besides the normal dna ligase activity present in the host pleurodeles eggs, rna can translate for the specific carried information revealing a difference between the two samples. moreov ... | 1985 | 4054231 |
regional specificity of glycoconjugates in xenopus and axolotl embryos. | this paper reviews work on the presence, synthesis and developmental regulation of glycoconjugates (proteoglycans, glycoproteins and glycolipids) in the early amphibian embryo. in the axolotl there is little regional specificity of protein synthesis until the tailbud stage, but substantial regional specificity of glycoprotein synthesis from the end of gastrulation. glycolipid synthesis is more uniform although a number of unique species are made in the epidermis. isolated explants from axolotl e ... | 1985 | 3913731 |
towards understanding paternal extragenic contributions to early amphibian pattern specification: the axolotl ts-1 gene as a model system. | as a model system for understanding the role sperm extragenic components might play in early embryogenesis the genetics and phenotype of the ts-1 axolotl (ambystoma mexicanum) mutant gene are reviewed. that mutant gene displays parental effects. it exhibits both maternal (egg-mediated) as well as paternal (sperm-mediated) phenotypic effects. a variety of possible modes of action of the ts-1 gene are reviewed. comparisons of various precedents to the ts-1 genetic data are made. in addition, novel ... | 1985 | 3841668 |
embryonic induction and cation concentrations in amphibian embryos. | explanted ectoderm from early gastrulae of triturus alpestris was treated with the na-k ionophore gramicidin (10(-9) to 10(-5) m) and the ca-ionophore a 23187 (10(-7) to 10(-5) m). the ectoderm developed almost exclusively to atypical epidermis as in the control explants. when the ectoderm was treated with ouabain (10(-4) m), intracellular na+ increased about 4.4-fold and k+ was reduced by half. mesenchyme cells in small number differentiated in about 40% of the ouabain-treated explants. the tim ... | 1985 | 2416476 |
an analysis of protein synthesis patterns during early embryogenesis of the urodele--ambystoma mexicanum. | changes in protein synthesis during early ambystoma mexicanum (axolotl) embryogenesis were monitored using two-dimensional (2-d) polyacrylamide gel electrophoresis. no change in synthesis patterns during progesterone-induced oocyte maturation was detected. in oocytes matured in vivo (unfertilized eggs), however, the synthesis of several oogenetic proteins ceased, only to be resumed later in development. at fertilization, one novel non-oogenetic protein was found. a cleavage-specific protein was ... | 1985 | 4093754 |
regeneration from isolated half limbs in the upper arm of the axolotl. | a technique enabling the isolation of half limb stumps using strips of skin from the head is described. using this technique posterior, dorsal and ventral halves of the upper arms of axolotls were constructed. all halves produced regenerates and regional differences were shown in the regenerative and regulative abilities of the different halves. posterior half stumps regenerated limbs with a mean digit number of 3.9 and had a normal dorsoventral muscle pattern. anterior halves produced hypomorph ... | 1985 | 4093751 |
a three-step scheme for gray crescent formation in the rotated axolotl oocyte. | it has been shown that various inhibitors of protein synthesis can elicit the precocious appearance of a gray crescent (gc) in in vitro maturing, nonactivated ambystoma mexicanum oocytes. however, evidence has now been obtained that these treatments fail to induce gc formation when the oocytes are enucleated before initiation of maturation. the ability to form a gc is reestablished in enucleated oocytes by the injection of nucleoplasm from a normal oocyte, either before or after the injection of ... | 1985 | 4007261 |
histological analysis of limb regeneration in postmetamorphic adult ambystoma. | previous investigation into the regenerative ability of postmetamorphic adult land phase ambystoma has revealed that these species have the capacity to completely regenerate a limb, given optimal environmental conditions, and the gross morphological characteristics of limb regeneration in these species compared favorably with the external regeneration morphology of aquatic phase forms. the present study concerns a histological and histochemical examination of the regenerating limb tissues and th ... | 1985 | 3842040 |
peanut lectin receptors in the early amphibian embryo: regional markers for the study of embryonic induction. | the regional and temporal specificity of peanut agglutinin binding was determined for early amphibian embryos. with the onset of neurulation, a receptor appears on the epidermis, but remains absent from the neural plate. a second type of receptor, largely masked by sialic acid, appears throughout the extracellular matrix. in the axolotl, the epidermal receptor is epimucin and the matrix receptor is fibronectin plus other components. both receptors are autonomously expressed, on schedule, by appr ... | 1985 | 3995583 |
cellular behavior in the anteroposterior axis of the regenerating forelimb of the axolotl, ambystoma mexicanum. | cellular behavior along the anteroposterior axis of the regenerating axolotl forelimb was studied by use of triploid (3n) tissue grafted into diploid (2n) hosts and three-dimensional computer reconstructions. asymmetrical upper forelimbs were surgically constructed with one half (anterior or posterior) 3n and the other half 2n. limbs were amputated immediately after grafting or were permitted to heal for 5 or 30 days prior to amputation. when regenerates had attained the stage of digital outgrow ... | 1985 | 3987961 |
regeneration of axolotl hindlimbs bearing surgically created discontinuities in the anterior-posterior axis. | the pattern regulation process in amphibian limbs has been examined with respect to the presence of discontinuities in the anterior-posterior (a-p) axis. limbs bearing such discontinuities were surgically created by contralateral exchange of either dorsal or ventral half thighs and these limbs were then amputated immediately after surgery. the results demonstrate that a-p discontinuities lead to the formation of extra limb structures during distal outgrowth in contrast to the mosaic behaviour of ... | 1985 | 4031745 |
neural fold and neural crest movement in the mexican salamander ambystoma mexicanum. | in studies of amphibian neurulation, the terms "neural ridge," "neural fold," and "neural crest" are sometimes used as synonyms. this has occasionally led to the misconception that grafting of the neural crest is equivalent to grafting of the neural fold. the neural fold, however, is composed of three parts: the neural crest, prospective neural tube tissue, and epidermis. in order to investigate how these neural fold components move during neurulation, time-lapse photography, electron microscopy ... | 1985 | 3989498 |
in vitro differentiation of neuronal precursor cells from amphibian late gastrulae; morphological, immunocytochemical studies, biosynthesis, accumulation and uptake of neurotransmitters. | neuronal differentiation has been studied in dissociated cell cultures from early neurulae of pleurodeles waltl and ambystoma mexicanum. cocultures were prepared from the neural primordium and underlying chordamesoderm. np and nf cultures were prepared from isolated neural plate and neural folds, respectively. neuronal precursors in np and nf cultures had distinctive aggregation properties already evident after 1-2 days in culture. after 10-15 days, mature neurones and synapses were observed by ... | 1985 | 2863321 |
normal fates and states of specification of different regions in the axolotl gastrula. | a fate map was constructed for four regions of the early gastrula of ambystoma mexicanum using orthotopic grafts from donors labelled with fldx (fluoresceinated-lysinated-dextran). the region around the animal pole gave rise to epidermis only and did not include prospective neural plate. the dorsal marginal zone contributed to cephalic endoderm and to the whole length of the axial mesoderm (notochord and somites), the lateral marginal zone to lateroventral and somitic mesoderm, and the ventral m ... | 1985 | 2411838 |
stimulation of initial neural crest cell migration in the axolotl embryo by tissue grafts and extracellular matrix transplanted on microcarriers. | the present experiments were designed to test whether the onset of neural crest cell migration in the embryonic axolotl trunk is stimulated by surrounding tissues and their associated extracellular matrix (ecm). tissue grafts, or embryonic ecm adsorbed in vivo onto inert "microcarriers" prepared from nuclepore filters, were placed close to the premigratory neural crest cells, and the embryos were then incubated to a specific stage. the experiments were evaluated with light microscopy, sem, and t ... | 1985 | 3972165 |
kinetics of light-sensitive channels in vertebrate photoreceptors. | we have studied the ion channels mediating the light response of vertebrate rod photoreceptors by analysing fluctuations in the current across the rod membrane, using the whole cell patch-clamp technique on rods isolated from the axolotl retina. light decreases the membrane current fluctuations. noise analysis reveals two components to this decrease: a low frequency component due to biochemical noise in the transduction mechanism, and a high frequency component we attribute to the random opening ... | 1985 | 2579400 |
eye enucleation and regeneration of neural retina in axolotl larvae (ambystoma mexicanum). | the eyes of axolotl larvae were enucleated at stages 30 and 37. animals with single dorsomedian eyes resulted in the first case (i.e. stage 30). when a piece of pigment epithelium was re-implanted into stage 37 animals at the site of the lesion, limited regeneration was observed when the implant formed a vesicle, but, when the pigment epithelium remained "open" regeneration of the neural retina was extensive. the possible resons for this difference was discussed. | 1985 | 4014704 |
experimental evidence for a proteinaceous presegmental wave required for morphogenesis of axolotl mesoderm. | mesoderm of axolotl embryos at various developmental stages was briefly exposed to a calcium-free 0.01% trypsin solution by temporary removal of the epidermis. this treatment was found to disrupt somite segmentation in a localized region and the pronephric duct was unable to migrate through this region. the affected area, consisting of 3.91 +/- 1.04 somites, traveled through the embryo in synchrony with, and 3.55 +/- 0.69-somite widths ahead of segmentation. trypsinization in the presence of 340 ... | 1985 | 3965323 |
retinoids and the control of pattern in regenerating limbs. | it has recently been discovered that, as well as having effects on cell division and differentiation, retinoids induce dramatic changes in the development of pattern in limbs. local application of retinoic acid to the anterior side of chick limb buds causes anteroposterior mirror-imaging such that the limb has six digits instead of three. in rana limb buds retinoids induce changes in both the anteroposterior and proximodistal axes. in regenerating axolotl limbs their effect is primarily on the p ... | 1985 | 3896698 |
a model of inward and outward membrane currents in cultured embryonic amphibian spinal neurons and reconstruction of the action potential. | a model of the membrane currents in embryonic amphibian neurons has been developed in order to investigate the ionic mechanisms underlying developmental changes in excitability. differentiating amphibian neurons both in situ and in vitro show a gradual change in the ionic sensitivity of their action potential from ca- to na-dependent, with an intermediate period in which the action potential shows a mixed ionic sensitivity. the model developed incorporates quantitative descriptions of na, ca and ... | 1985 | 2422357 |
the response of denervated axolotl arms to delayed amputation. | forearms of juvenile axolotls can be kept denervated for up to 4 weeks by deflecting brachial nerves to the flank. a more orthodox second denervation prolongs this state up to a total of six weeks. the denervated arms are unable to regenerate for the whole period, but eventually become reinnervated and then regenerate normally. these results and analogous experiments on adult newts prompt a partial retraction and reinterpretation of my previous report on regeneration after prolonged denervation. | 1984 | 6533253 |
the cellular contributions of blastema and stump to 180 degrees supernumerary limbs in the axolotl. | by inverting triploid blastemas onto diploid stumps (and vice versa) the cellular contributions to supernumerary limbs so generated have been assessed. the four classes of 180 degrees supernumerary limbs each had a different mixture of stump and blastemal cells. the mesoderm of normal supernumeraries was composed entirely or almost entirely of stump cells and were always of stump handedness. the mesoderm of symmetrical supernumeraries was of variable composition, it could be mostly stump, mostly ... | 1984 | 6533251 |
accumulation and localization of troponin-t in developing hearts of ambystoma mexicanum. | troponin-t (tn-t) expression in developing hearts of axolotls, ambystoma mexicanum, was studied with the use of polyclonal and monoclonal antibodies and sds-polyacrylamide gel electrophoresis. in precontractile hearts (stage 32/33), tn-t was present in addition to myosin, actin and tropomyosin as evidenced by the presence of the protein bands in sds-gels and by indirect immunofluorescence. tn-t was localized in amorphous collections at the peripheries of these precontractile cells. hearts of nor ... | 1984 | 6442732 |
the distribution of marked dermal cells from small localized implants in limb regenerates. | numerous experiments have demonstrated that skin has a profound influence on the pattern of limb regeneration in urodeles. in this investigation, the fate during regeneration of marked cells derived from narrow strips of skin inserted into different positions around the limb circumference has been followed. skin strips were taken from triploid axolotls and transplanted into diploid sibling animals. the distribution of trinucleolate cells was determined at the site of amputation and in the regene ... | 1984 | 6389219 |
anchoring filaments of the amphibian epidermal-dermal junction traverse the basal lamina entirely from the plasma membrane of hemidesmosomes to the dermis. | an electron microscopical study of the epidermal-dermal junction in the axolotl and adult rana pipiens has been carried out. this shows that filaments of about 12nm in diameter, known as anchoring filaments, pass from the hemidesmosomes at the base of the epidermal cells across the basal lamina to the dermis. there they may unite to form broader fibres, known as anchoring fibrils, or may simply form bundles. in the axolotl, particularly, the anchoring fibrils or bundles of anchoring filaments, e ... | 1984 | 6335885 |
axial characteristics of nerve induced supernumerary limbs in the axolotl. | supernumerary limbs were produced by deviating the sciatic nerve to the surface of the axolotl hindlimb either alone or in combination with small skin grafts from specific limb positions. with no skin grafts a very low frequency of good supernumeraries were produced. however, when associated with skin grafts, this frequency was significantly increased. the pattern of skeletal elements and muscles were analysed in the supernumeraries which formed at each location. in both the anterior-posterior a ... | 1984 | 28305105 |
xanthophores in chromatophore groups of the premigratory neural crest initiate the pigment pattern of the axolotl larva. | the barred pigment pattern (lehman 1957) of the axolotl larva is best observed from stage 41 onwards, where it already consists of alternating transverse bands of melanophores and xanthophores along the dorsal side of the trunk. the present study investigateswhen the two populations of neural crest derived chromatophores, melanophores and xanthophores become determined andhow they interact to create the barred pigment pattern. the presence of phenol oxidase (tyrosinase) in melanophores (revealed ... | 1984 | 28305101 |
[radioautographic study of the cellular proliferation of retinal pigment epithelium in axolotls]. | the proliferative activity of the pigment epithelium cells in the axolotl eyes was studied using 3h-thymidine in two types experiments: after the removal of lens, iris and retina and upon the cultivation of the pigment epithelium pieces in the cavity of lens-less eye. irrespective of the operation type, the level of proliferation of the pigment epithelium cells changed regularly with respect to the time of observation. in the intact eye, the level of proliferation of the pigment epithelium cells ... | 2006 | 6521975 |
is the na+,k+-atpase symmetrically distributed in the neuroepithelium of the vestibular system in the axolotl (ambyostoma mexicanum)? | this study was undertaken to assess the localization of the na+,k+-atpase in the neuroepithelial cells of the macula sacculi. in vitro perilymphatic (basolateral) perfusion with ouabain produced a significant drop in the membrane potential. endolymphatic (apical) application of ouabain had practically no effect on membrane potentials. this suggests that na+,k+-atpase is asymmetrically distributed in the neuroepithelial cells. | 1984 | 6151945 |
off-pathway synaptic transmission in the outer retina of the axolotl is mediated by a kainic acid-preferring receptor. | intracellular recordings were made from off-centre bipolar cells and horizontal cells in the superfused axolotl retina eyecup preparation. bath-applied (+/-)cis-2,3-piperidine dicarboxylic acid (pda), gamma-d-glutamylglycine (dgg), l-glutamic acid diethyl ester (gdee), (+/-)2-amino-5-phosphonovaleric acid (2-apv) and magnesium ions were assessed as antagonists of the actions of the photoreceptor transmitter. the rank order of antagonist efficacy was pda greater than dgg greater than greater than ... | 1984 | 6093015 |
[nuclear behavior of embryonic cells and growing oocytes from the clawed toad in the cytoplasm of maturing axolotl oocytes]. | the behaviour of the nuclei of the x. laevis vitellogenic oocytes was studied by their transplantation into the cytoplasm of the axolotl maturing oocytes. after the germinal vesicle breakdown, in the case the transplanted nuclei were located close to each other a common giant spindle united the chromosomes of all transplanted nuclei. a mosaic spindle united sometimes the chromosomes of the two amphibian species. the embryonic nuclei transplanted in the cytoplasm of the maturing oocytes formed, a ... | 2006 | 6504501 |
cellular contribution to supernumerary limbs resulting from the interaction between developing and regenerating tissues in the axolotl. | the relationship between limb development and limb regeneration is considered with regard to the mechanisms by which pattern is established during limb outgrowth. in a previous paper (muneoka, k. and bryant, s. v. 1982 nature (london) 298, 369-371) the interaction between cells from the developing limb bud and the regenerating limb blastema was found to result in the production of organized supernumerary limb structures. in this paper the relative cellular contribution from developing and regene ... | 1984 | 6468758 |
cellular contribution to supernumerary limbs in the axolotl, ambystoma mexicanum. | using the triploid cell marker, the cellular contribution from graft and stump to the supernumerary limbs which result from controlateral grafts of limb buds and regeneration blastemas in the axolotl has been analyzed. grafts were made so as to appose anterior and posterior limb positions. overall, the contribution from graft and stump tissue was found to be approximately equal although the position of the boundary between the two was variable from limb to limb. this result is consistent with mo ... | 1984 | 6468757 |
improved techniques for use of the triploid cell marker in the axolotl, ambystoma mexicanum. | techniques for using the triploid cell marker for studying cell lineage during the development and regeneration of the axolotl limb are described. triploid animals possess cells with three nucleoli while diploid animals possess cells with two nucleoli. we have developed a technique for isolating the limb dermis as a sheet of cells for whole-mount analysis of cellular ploidy. whole-mount tissue preparations as well as paraffin-embedded sectioned tissues were stained specifically for nucleoli with ... | 1984 | 6205921 |
regeneration of surgically created mixed-handed axolotl forelimbs: pattern formation in the dorsal-ventral axis. | the regeneration of surgically created mixed-handed limb stumps is examined in the axolotl. operations were performed in the lower arm and upper arm regions and grafts were allowed to heal for approximately one month prior to amputation or were amputated immediately. in the lower arm group both anterior and posterior limb halves were inverted, whereas only posterior halves were inverted in the upper arm group. almost all the limbs regenerated were normal in the anterior-posterior axis, whereas a ... | 1984 | 6491582 |
a voltage-gated hydrogen ion current in the oocyte membrane of the axolotl, ambystoma. | membrane currents in the immature oocyte of the urodele amphibian ambystoma were studied using the two-micro-electrode voltage-clamp technique. a current carried by h ions (ih) constituted the major portion of outward current activated by depolarizations from the resting voltage (about -60 mv). net inward current was not observed at this developmental stage. the reversal potential for ih measured from tail currents obtained in two step voltage-clamp experiments shifted by 54 mv per unit change i ... | 1984 | 6086909 |
retinoic acid-induced pattern duplication in regenerating urodele limbs. | the effects of varying doses of retinoic acid on forelimb regeneration in larval ambystoma mexicanum amputated through the wrist joint and in adult notophthalmus viridescens amputated through the basal carpals were compared. in both species, the major effect of retinoic acid was to cause the proximodistal duplication, in the regenerate, of stump segments proximal to the amputation plane. transverse axial duplications (anteroposterior and dorsoventral) occurred in a smaller percentage of cases; t ... | 1984 | 6724131 |
the pigmentary system of developing axolotls. ii. an analysis of the melanoid phenotype. | the melanoid mutant in the mexican axolotl (ambystoma mexicanum) is analysed with respect to the differentiation of pigment cells. pigment cells were observed with the transmission electron microscope in order to determine any unusual structural characteristics and to determine what happens to each of the cell types as development proceeds. chemical analysis of pteridine pigments was also carried out, and changes in pteridine biosynthesis were found to correlate well with changes in xanthophore ... | 1984 | 6470606 |
the pigmentary system of developing axolotls. i. a biochemical and structural analysis of chromatophores in wild-type axolotls. | a biochemical and transmission electron microscopic description of the wild-type pigment phenotype in developing mexican axolotls (ambystoma mexicanum) is presented. there are three pigment cell types found in adult axolotl skin - melanophores, xanthophores and iridophores. both pigments and pigment cells undergo specific developmental changes in axolotls. melanophores are the predominant pigment cell type throughout development; xanthophores occur secondarily and in fewer numbers than melanopho ... | 1984 | 6470605 |
in vitro development of isolated ectoderm from axolotl gastrulae. | the development of ectoderm isolated from the animal pole of axolotl gastrulae is monitored by light microscopy, electron microscopy and analysis of newly synthesized proteins, glycoproteins and glycolipids. when control embryos are undergoing neurulation it is shown that the explants autonomously begin to express epidermal markers and do not express mesodermal markers. however the results suggest that not all the cells become epidermal and electron microscope examination shows that only the out ... | 1984 | 6747530 |
regional biosynthetic markers in the early amphibian embryo. | a search has been made for regional differences in macromolecular synthesis in the axolotl embryo at a stage when the principal regions have become determined but terminal differentiation has not yet begun. the epidermis of the neurula makes a number of abundant proteins which are not made elsewhere. some of these are identified by immunoprecipitation as cytokeratins (relative molecular masses (mr) 62,59,54,51 and 46 x 10(3)). at the same stage a network of tonofilaments becomes visible by elect ... | 1984 | 6747529 |
[regeneration of isolated skeletal muscle tissue in the axolotl ambystoma mexicanum]. | | 2014 | 6723509 |
skin glands in the axolotl: the creation and maintenance of a spacing pattern. | the morphogenesis of skin glands in the larval axolotl is described at the light microscope level. the glands are derived from the epidermis, but are eventually located in the dermis. the glands are non-randomly arranged within the skin and the spacing pattern tends towards a hexagonal array in two dimensions. analysis of the spacing pattern in animals of different sizes reveals that a clear relationship exists between gland size and the distance between glands. occasionally, new small glands ar ... | 1984 | 6716048 |
genetic mapping in the mexican axolotl, ambystoma mexicanum. | in the mexican axolotl, ambystoma mexicanum, gynogenetic diploids can be produced by suppressing the release of the second polar body in eggs activated with irradiated sperm. if the female is heterozygous for a particular mutation, some of the progeny will be homozygous for the mutation. the proportion depends on the distance from the centromere and can be used to determine the gene--centromere (or gene-kinetochore) distance. the mapping function is based on the neurospora tetrad mapping functio ... | 1984 | 6704787 |
discovery and initial characterization of a new conditional (temperature-sensitive) maternal effect mutation in the axolotl. | the discovery of a new temperature-sensitive maternal effect mutation in ambystoma mexicanum is described. the new gene (ts-1) was recognized when 100% of the eggs spawned by homozygous females failed to develop past early gastrulation when reared at 25 degrees c. eggs raised at 10 degrees c developed normally to sexual maturity. a temperature-sensitive period during blastulation was identified by a preliminary series of temperature shifts. histologic examination revealed that nuclear abnormalit ... | 1984 | 6734988 |
neural crest cell behavior in white and dark larvae of ambystoma mexicanum: differences in cell morphology, arrangement, and extracellular matrix as related to migration. | melanocytes of white (d/d) larvae of the mexican axolotl (ambystoma mexicanum) are confined to the dorsal midline of the trunk region, whereas in dark (d/-) larvae they are spread laterally on the flank as well, where they contribute to the normal pigment pattern of the trunk. pigment cell migration in the subepidermal space of white larvae is inhibited by the white epidermis (dalton '50; keller et al., '82). the present scanning electron microscopic study describes a well-defined sequence of ch ... | 1984 | 6699590 |
neural crest cell behavior in white and dark larvae of ambystoma mexicanum: time-lapse cinemicrographic analysis of pigment cell movement in vivo and in culture. | the pattern of migration and motile activity of developing pigment cells of the mexican axolotl, ambystoma mexicanum, were analyzed by time-lapse cinemicrography in vivo and in culture. in vivo, melanocytes of dark (d/-) larvae migrate from dorsal to ventral in a highly directional manner. they are elongated and aligned parallel to the direction of migration. nearly all protrusive activity occurs at their ventral, leading edges. translocation occurs at a mean rate of 0.7 micron/min and involves ... | 1984 | 6699589 |
calmodulin during development and metamorphosis in urodelan amphibians. | calmodulin isolated and purified to homogeneity from young larvae is very similar to that obtained from adult pleurodeles waltlii and these proteins are almost identical to previously described vertebrate calmodulins. during p. waltlii development, an increase in total individual calmodulin content is observed after the heart beating stage. in dorsal axial muscle, calmodulin level which is very high at the beginning of larval life (premetamorphosis) decreases strikingly in the first part of prom ... | 1984 | 6537929 |
a steady efflux of ionic current predicts hind limb development in the axolotl. | for more than a week prior to the emergence of a hind limb, a steady electric current is driven out of the ventrolateral flank in the immature axolotl, returning through the integument in adjacent regions of the body. a marked peak in the density of this outcurrent could be observed over the exact area of hind limb formation 4 to 6 days prior to its appearance. after a bud projected from the flank, current densities were observed to decrease in magnitude yet localize about the early limb. in abo ... | 1983 | 6663262 |
[proliferative activity of the pigment epithelium and regenerating retinal cells in ambystoma mexicanum]. | cellular sources of retinal regeneration and proliferative activity of the cells taking part in retina restoration have been studied in axolotls using 3h-thymidine. the cells of ciliary-terminal zone proved to be the main source of retinal restoration. besides these cells, the pigmented cells of the iris inner and outer layers and pigment epithelium cells can take part in this process. morphological stages of retinal regeneration have been established and regular changes in the level of prolifer ... | 2006 | 6657169 |
spastic mutant axolotl: identification of a phenocopy pathway with implications for the control of axolotl swimming by the vestibulocerebellum. | the spastic mutant axolotl shows abnormal swimming behavior, which includes a preponderance of "embryonic" swimming elements (coils) versus mature swimming elements (sinusoids) and a failure to entrain sinusoids into a prolonged swimming sequence. the mutant also shows anatomical disorganization in the area acousticolateralis and cerebellar auricle, but it is unclear (1) to what extent the behavioral abnormalities are traceable to the vestibulocerebellar defect or (2) how the vestibulocerebellar ... | 1983 | 6643720 |
the effect of vitamin a on the regenerating axolotl limb. | these experiments describe further investigations into the effects of vitamin a on regenerating limbs. the effects of different retinoids, the time of administration, concentration of vitamin a and histological, autoradiographic and histochemical studies are reported. the most obvious result of vitamin a treatment is to cause proximal elements to regenerate from distal amputation levels, that is to cause serial reduplication of pattern in the proximodistal axis. retinoic acid was the most potent ... | 1983 | 6655434 |
the effect of vitamin a on limb regeneration in rana temporaria. | previous experiments in which vitamin a has been administered to developing or regenerating limbs have shown that different limb axes are affected. in regenerating axolotl limbs, serial reduplications in the proximodistal axis are produced. in the developing chick limb bud, mirror-imaged reduplications in the anteroposterior axis are produced. results reported here on rana temporaria limb buds reveal that vitamin a causes both effects to occur. that is, limbs are both serially reduplicated in th ... | 1983 | 6603380 |
fertilization of amphibian eggs: a comparison of electrical responses between anurans and urodeles. | in pleurodeles waltl and ambystoma mexicanum, which exhibit physiological polyspermy, the membrane potential in most eggs did not change in any consistent pattern during 45 min after fertilization; in some cases, a slow hyperpolarization began 5 to 15 min after insemination and continued for 10-15 min. these eggs then slowly depolarized, reaching a stable value of -10 to +10 mv, about 45 min after fertilization. membranes of eggs activated by a23187 or by electrical stimulus showed a similar beh ... | 1983 | 6603379 |
gross morphological analysis of limb regeneration in postmetamorphic adult ambystoma. | due to the great disparity between regeneration times for the larval salamander (40 days), axolotl (30+ days), newt (44 days), and adult salamander (155 to 370 days), a staging system was devised so correlative comparisons could be made between regenerative model systems. the sequence was based on two criteria: 1) the stages should be similar to previously reported sequences for the newt, axolotl, and larval salamander, and 2) the stages must be readily recognizable by examination of the externa ... | 1983 | 6614512 |
experimental studies on a lethal gene (t) in the mexican axolotl, ambystoma mexicanum. | in the mexican axolotl, ambystoma mexicanum, the developmental mutation lethal t is inherited as a simple mendelian recessive. mutant larvae failed to feed and died, on the average, 17 days after hatching. unfed wild-type larvae died an average of 23 days after hatching. by 15 days, forelimb development had progressed further in the wild type; a cartilaginous scapula and humerus were present, but no cartilage was seen in the mutant limb. histological examination indicated that the visceral carti ... | 1983 | 6886665 |
muscle and cartilage differentiation in axolotl limb regeneration blastema cultures. | a tissue culture system is described for explants of mesenchyme from ambystoma mexicanum limb regeneration blastemas. explants were cultured on collagen substrate for 3 weeks in minimal essential medium supplemented with the hormones insulin, thyroxine, somatotropin, and hydrocortisone, plus beef embryo extract (ee), 2%. this medium supported extensive cell migration onto the substrate followed by cell proliferation and differentiation of both cartilage matrix and myotubes. cultures on plastic s ... | 1983 | 6886662 |
assessment of mutagenic damage following ethyl methanesulfonate mutagenesis in the axolotl (ambystoma mexicanum). | when male axolots (ambystoma mexicanus) were treated with 100 mg/liter of ethyl methanesulfonate (ems), a dominant lethal effect was obtained. embryonic survival of f1 progeny was most severely reduced between about 50 and 150 days after treatment. dominant lethal lesions probably consist of chromosome breaks that lead to loss of parts of chromosomes or entire chromosomes. the appearance of embryos with a single nucleolus was used to assess this type of damage. the peak incidence of such embryos ... | 1983 | 6886657 |
pattern regulation in the anterior half of the embryonically produced symmetrical forelimb of the axolotl, ambystoma mexicanum. | symmetrical forelimbs were created in the axoltl by performing surgery on embryos at stages 32-34. the technique of j.m.w. slack (j. embryol. exp. morphol., 39:151-168, 1977) was utilized. several experiments were then performed to test the ability of these symmetrical forelimbs to participate in pattern formation. when symmetrical limbs were amputated without previous surgery, 58% failed to regenerate. when symmetrical limbs were wounded in the plane of symmetry and permitted to heal for 30 day ... | 1983 | 6613906 |
[an anatomical study of teeth in the axolotl (siredon mexicanum)]. | | 1983 | 6585764 |
control of dna ligase molecular forms in nucleocytoplasmic combinations of axolotl and pleurodeles. | a light form of dna ligase (ec 6.5.1.2), the only form present in oocytes of the axolotl (ambystoma mexicanum), has been shown to be replaced by a heavy form of the enzyme when the egg enters cleavage. this early biochemical event has been assumed to rely on direct nuclear input. sucrose gradient analysis permits discrimination between enzymes from axolotl and the sharp-ribbed salamander (pleurodeles waltlii) for both heavy and light enzymatic forms of dna ligase. genetic activity of blastula nu ... | 1983 | 6574490 |
inhibition of protein synthesis elicits early grey crescent formation in the axolotl oocyte. | in the axolotl (ambystoma mexicanum shaw), it was recently shown that cycloheximide (ch) could induce early grey crescent formation (egc) in non-activated oocytes, maturing in vitro (grinfeld and beetschen 1982). since it was not proved that egc was a consequence of protein synthesis inhibition rather than a side-effect of the drug, experiments were performed using microinjections of a quite different inhibitor, diphtheria toxin (dt). this toxin also appeared to elicit egc. incorporation of (3h) ... | 1983 | 28305127 |
the structure of supernumerary limbs formed after 180 degrees blastemal rotation in the newt triturus cristatus. | the structure of supernumerary limbs formed following 180 degrees ipsilateral blastema rotations in the arm of the newt triturus cristatus is analysed. both the skeletal pattern and the muscle patterns are examined. as is the case after comparable experiments in the axolotl (see, for example, maden & mustafa, 12982) the extra limbs which form show a range of anatomies. limbs symmetrical about the dorsal-ventral and anterior-posterior axis are reported as well as some limbs which were part symmet ... | 1983 | 6886592 |
differences between embryos and adults in the plasticity of somatosensory afferents to the axolotl tectum. | the plasticity of somatosensory afferents in the adult axolotl tectum was studied in two ways. first, normal adult axolotls were monocularly enucleated, and second, adult animals which had been monocular since embryogenesis had the tectum contralateral to the remaining eye excised. after a survival time of about one year the brains of these animals were studied electrophysiologically and histochemically. in the enucleated adults, the deprived tectum lacked visual activity, and the acetylcholines ... | 1983 | 6850352 |
dna ligase in axolotl egg: a model for study of gene activity control. | replacement of the light form of dna ligase (6 s) by the heavy form (8 s) in activated egg of axolotl has been studied as a model for change in genetic activity exerted by the female pronucleus. nuclear transplantation shows that a blastula nucleus is able to govern the replacement of the light ligase by the heavy one. the result is not the same if the grafted nucleus is taken from an androgenetic embryo, devoid of the heavy enzyme. therefore the change in the properties of the female pronucleus ... | 1983 | 6832475 |
neurulation in the mexican salamander (ambystoma mexicanum): a drug study and cell shape analysis of the epidermis and the neural plate. | we analysed the neurulation movements in the mexican salamander ambystoma mexicanum. embryos were exposed to colchicine or nocodazole prior to neural fold formation. exposure to these drugs prevented the anterior neural folds from closing. neurulation however proceeded normally in the posterior regions of the embryo. we were unable to find apically constricted cells in the neural plate of colchicine-blocked neurulae. only rounded-up neural plate cells were present (semithin sections). this situa ... | 1983 | 6684145 |
hormonal control of glycogenolysis and the mechanism of action of adrenaline in amphibian liver in vitro. | in in vitro cultures of liver from ambystoma mexicanum glycogenolysis was stimulated by adrenaline, glucagon, and vasopressin in a dose-dependent manner. maximum activity was seen at 10(-6) m hormone while 10(-9) m was without effect. dibutyryl cyclic amp (10(-3) m) stimulated glycogenolysis maximally although 10(-5) m had no effect. the glucose release brought about by adrenaline was blocked by the beta-adrenergic antagonist propranolol but not by prazosin or yohimbine which are alpha 1- and al ... | 1983 | 6301936 |
reversal of developmental competence in inverted amphibian eggs. | inverted amphibian embryos were employed for an analysis of pattern formation in early embryogenesis. axolotl (ambystoma) and xenopus eggs were inverted prior to the first cleavage division and permitted to develop upside down to the early gastrulation stage. in both cases the cleavage patterns of the animal and vegetal hemispheres were reversed. by gastrulation, however, developmental arrest began, and no inverted embryos developed beyond neurulation. the state of competence of the animal and v ... | 1983 | 6683745 |
positional information in the forelimb of the axolotl: properties of the posterior skin. | two series of experiments were carried out to investigate the properties of the positional information carried by posterior skin of the axolotl forelimb. the skin was assayed by grafting it to the anterior side of a normal limb and then amputating through the graft region. the formation of a double posterior regenerate indicates that the grafted skin carried the posterior coding. in the first series, double posterior limbs were created by grafting posterior half limb rudiments to the flank of ta ... | 1983 | 6348201 |
effects of immunization, adult thymectomy and irradiation on axolotl spleen lymphocytes: discontinuous ficoll density gradients analysis. | | 1983 | 6873432 |
regional differences of protein synthesis in the limb regeneration blastema of the axolotl. | | 1983 | 6828516 |
morphogenesis of the regenerating limb blastema of the axolotl: shape, autonomy and pattern. | | 1983 | 6828512 |
[cell satellites and postsatellites in the muscle tissue of the adult ambystoma mexicanum]. | | 1983 | 6662019 |
fibronectin in early amphibian embryos. migrating mesodermal cells contact fibronectin established prior to gastrulation. | the three-dimensional organisation of fibronectin (fn) in early amphibian embryos (ambystoma mexicanum, pleurodeles waltlii) was studied with the use of antibodies against amphibian-fn. immunofluorescence labelling was performed on whole-mount specimens. it was shown that before gastrulation an extensive extracellular network consisting of anastomosed fn-fibrils underlies the roof of the blastocoel prior to the migration of mesodermal cells. initially, fn-fibrils develop radially on the inner su ... | 1983 | 6640612 |
[formation of the gray crescent, induced in axolotl oocytes during maturation, depends on factors of nuclear origin]. | inhibitors of protein synthesis can elicit the precocious appearance of a grey crescent (gc) in in vitro maturing ambystoma mexicanum oocytes. this treatment however fails to induce gc formation when the oocytes are enucleated before initiation of maturation. the ability to form a gc is reestablished in enucleated oocytes by the injection of nucleoplasm from a normal oocyte, either before or after injection of the inhibitor. in the latter case, the gc appears even though the protein synthesis le ... | 1983 | 6412990 |
maturation of transplantation antigens in ambystoma mexicanum. | both juvenile (14-16 week) and adult (18 month) ambystoma mexicanum reject skin allografts from adult ambystoma more speedily than they reject such grafts from juvenile axolotls. donor-specific histocompatibility antigen, prepared from splenocytes, is more effective in inhibiting adult host splenocyte migration when the antigen is prepared from spleen cells from adult, rather than from juvenile ambystoma. the thymus is fully developed in juvenile ambystoma, suggesting that the delayed kinetics o ... | 1983 | 6341109 |
the effects of adenyl compounds on the heart of the axolotl (ambystoma mexicanum). | in the spontaneously beating axolotl atrium, adenosine 5'-triphosphate (atp) produced initial excitation followed by inhibition and then by a secondary excitation. this third phase of the atp response was only seen in electrically driven preparations in the presence of 8-phenyltheophylline (8-pt), an adenosine receptor antagonist. alpha,beta-methylene atp (apcpp), a stable analogue of atp, produced only excitatory effects, while adenosine and beta,gamma-methylene atp (appcp), a slowly degradable ... | 1983 | 6140115 |
retinofugal pathways from albino eyes embryonically transplanted to normal and albino axolotls. | albino axolotl eyes were transplanted embryonically to normal and albino axolotl hosts. the animals were allowed to mature for several months and then their transplanted eyes were injected with tritiated proline. the projections from these albino eyes were compared with those obtained from similar transplants of normally pigmented eyes. special attention was paid to the crossed and uncrossed components of the projections. no differences were found between normal and albino transplants. these res ... | 1982 | 7150982 |
expansion of the visual projection to the tectum of axolotls during metamorphosis. | during artificially induced metamorphosis in axolotls, the indirect visual projection from the ipsilateral eye develops followed by the expansion of the contralateral direct projection to occupy most of the tectal surface. during expansion the ipsilateral input is temporarily lost indicating the functional interdependence of the two projections. final stabilization of the projections and congruence of the ipsilateral and contralateral inputs is achieved a month after arrival on land. | 1982 | 6185185 |
enzyme clusters during the metamorphic period of ambystoma mexicanum: role of thyroid hormone. | enzyme activities and dna content have been measure in axolotl liver during the metamorphic period (4-8 months after spawning). three different types of enzyme activity profiles were observed. in the type i profile (carbamoyl-phosphate synthase, arginase, ornithine transcarbamoylase, and glutamate dehydrogenase) enzyme activity is high in the youngest animals studied, and shows a minimum at 5 months followed by a maximum at 8 months of age. thereafter activities do not change or slightly decreas ... | 1982 | 6128371 |
pattern regulation during regeneration of embryonically produced symmetrical forelimbs in the axolotl, ambystoma mexicanum. | embryonic axolotls (stages 32-34) underwent surgery during which a graft of flank tissue was transferred from a donor animal to the anterior margin of the forelimb field in a host animal. double-posterior forelimbs containing from one to eight digits developed. these limbs were amputated at a level proximal to the elbow to assess their regenerative ability. the majority (62%) of these limbs failed to regenerate externally visible structures. symmetrical limbs bearing five digits or more than fiv ... | 1982 | 7130935 |
protein synthesis during limb regeneration in the axolotl. | a study has been made of limb regeneration in the axolotl using two-dimensional gel electrophoresis of proteins labelled with [35s] methionine. in the early stages of regeneration seven proteins are identified which are specific to the mesenchyme and thirteen which are specific to the epidermis. these is very little change in the gel pattern until the onset of overt cytodifferentiation upon which the muscle and cartilage become substantially different both from each other and from the blastemal ... | 1982 | 7142900 |
axial organization of the regenerating limb: asymmetrical behaviour following skin transplantation. | an extensive series of skin grafting operations has been performed to investigate axial organization in the regenerating axolotl limb. semicircular cuffs of skin from either anterior, posterior, dorsal or ventral surfaces were exchanged between right and left limbs thereby creating limbs with double anterior, double posterior, double dorsal or double ventral skin, all with normal internal tissues. both fore and hindlimbs were used at both upper and lower limb levels. following amputation through ... | 1982 | 6754846 |
evidence that patterning mechanisms in developing and regenerating limbs are the same. | some amphibians have the ability to form new limbs throughout their lives. the essential similarity between limb regeneration and the original development of the limb is that both involve the elaboration of new patterns of structures. while some investigators believe that the two developing systems use similar mechanisms to generate the limb pattern, others have stressed the basic differences in developing the regenerating limbs, and have concluded that different mechanisms exist. both developin ... | 1982 | 7088182 |
early grey crescent formation experimentally induced by cycloheximide in the axolotl oocyte. | the effects of cycloheximide (ch) on grey crescent formation in artificially maturedambystoma mexicanum oocytes were determined. ch induced grey crescent formation after a few hours, especially after a 45° to 90° rotation from the vertical animal-vegetal axis. with low concentrations of ch (about 0.5 ng/oocyte), meiosis was still able to proceed normally to the stable second metaphase stage, but higher concentrations blocked it after 1st polar body extrusion and an interphasic nucleus appeared. ... | 1982 | 28305050 |
quantification of tropomyosin by radioimmunoassay in developing hearts of cardiac mutant axolotls, ambystoma mexicanum. | recessive mutant gene c in axolotls results in a failure of embryonic heart function. earlier morphological studies showed that the mutant myocardial cells lack organized sarcomeric myofibrils. electrophoresis and immunofluorescent studies suggested that the mutant heart cells contain substantial amounts of actin, myosin and alpha-actinin; however, tropomyosin appeared deficient. in the present study, we employed a newly developed extremely sensitive solid-phase radioimmunoassay method to quanti ... | 1982 | 7107867 |
the growth of segmental nerves from the spinal cord to the hind limb-bud in the axolotl. | it has been concluded from previous experiments involving the growth of segmental nerves from the amphibian spinal cord to the limb-bud that axons are attracted to the limb-bud region by their target tissue (hamburger, 1929; hughes and tschumi, 1958). in the present study this hypothesis has been tested by obstructing the pathways over which the nerves normally grow. it was found that for those nerves which marginally obstructed far fewer axons were able to reach their target. the spinal ganglia ... | 1982 | 7115218 |
the regeneration of axolotl limbs covered by frog skin. | | 1982 | 7042417 |
the transplantation of eyes to genetically eyeless salamanders: visual projections and somatosensory interactions. | eyes were transplanted from normal axolotls to eyeless mutants, and several anatomical and physiological observations were made on the central visual centers in these animals. some central projections were bilateral to the optic centers of the thalamus and midbrain, some traveled ipsilaterally to the same centers, and the rest grew down the spinal cord. this is similar to what has been found in eyes transplanted to normal hosts. the type of projection made in eyeless hosts correlated with the si ... | 1982 | 7062113 |
synaptogenesis and its relation to growth of the postsynaptic cell: a quantitative study of the developing mauthner neuron of the axolotl. | we describe the relation between growth and branching of an identified dendrite and the formation of synapses on its surface during a 3 1/2-day period early in development. we studied the lateral dendrite and the adjacent lateral perikaryon of the mauthner cell (m-cell) during embryonic stages 39-43 in the axolotl ambystoma mexicanum. reconstructions from light micrographs of serial sections through the cell revealed that during this interval the dendrite elongates rapidly, and large numbers of ... | 1982 | 7061738 |
electrophysiological evidence of electroreception in the axolotl siredon mexicanum. | | 1982 | 7063140 |
partial denervation effects on limb cartilage regeneration. | partially innervated axolotl arms gave regenerates of reduced size with deficient skeletal element replacement. this deficiency was most pronounced when nerve 4 (the largest of the brachial nerves) estimated to make up 50-60% of forelimb axons was removed by repeated resection. nerve 3 or 5 removal gave less pronounced reduction deformities in the newly formed regenerate. the dependency of skeletal element formation upon nerves is emphasized but does not follow a strict segmental subtraction in ... | 1982 | 7125236 |
prospective forebrain-midbrain from axolotl neurulae can be reprogrammed to differentiate as mauthner cell-containing medulla. | in premetamorphic amphibians, the mauthner cells (m-cells), a single pair of large neurons, are present in the medulla at ear level. m-cells are easily identified morphologically. lability of the major axes of the cns in the axolotl (ambystoma mexicanum) through midneural plate stages suggests that regionalization of the cns does not occur prior to that time. thus, prospective forebrain-midbrain from early midneurulae was unilaterally substituted for prospective hindbrain in hosts of the same st ... | 1982 | 7055713 |
neural crest cell behavior in white and dark embryos of ambystoma mexicanum: epidermal inhibition of pigment cell migration in the white axolotl. | | 1982 | 7054006 |
the alveolar-lining layer in the lung of the axolotl, ambystoma mexicanum. an electron-microscopic study using heavy metal complexes. | lungs of neotenic larvae of ambystoma mexicanum were prepared for maintaining the air-tissue boundary during aldehyde fixation. four methods of postfixation were applied: 1) osmium tetroxide followed by en-bloc staining with uranyl acetate and phosphotungstic acid, 2) ruthenium redosmium tetroxide, 3) osmium tetroxide-ferrocyanide, and 4) tannic acid-osmium tetroxide. three types of cells line the inner surface of the axolotl lung: 1) pneumocytes, covering the capillaries with flat cellular exte ... | 1982 | 6174238 |
suppression of first cleavage in the mexican axolotl (ambystoma mexicanum) by heat shock or hydrostatic pressure. | androgenetic diploid axolotls were produced by ultraviolet inactivation of the egg pronucleus shortly after fertilization, followed by suppression of the first cleavage division by hydrostatic pressure or heat shock. after treatment at 14,000 psi for 8 minutes, diploidy was restored in 74% of the embryos, but only 0.8% survived to hatching. a 36-37 degrees c heat shock of 10-minutes duration, applied 5.5 hours after the eggs were collected, yielded a slightly lower percentage of diploids. howeve ... | 1981 | 7338728 |
cellular contacts between hindbrain and prospective ear during inductive interaction in the axolotl embryo. | in the amphibian embryo, beginning in the late neurula and continuing through midtailbud stages, the developing medulla exerts an inductive influence on the prospective ear, effecting its determination. fine structural analysis of the region of closest apposition between the two tissues in the axolotl (ambystoma mexicanum) revealed that during this period, there is a significant increase in the surface area of the apposed cells through the projection of long finger-like processes that traverse t ... | 1981 | 7338713 |