Publications

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
comparative analysis of amphibian somite morphogenesis: cell rearrangement patterns during rosette formation and myoblast fusion.	detailed sem observations of the changes in cellular morphology, arrangements, and contacts that occur during the process of somite formation were made in two species of urodele amphibians, ambystoma mexicanum and pleurodeles waltlii, and one species of anuran amphibian, rana sphenocephala. after fixation, embryos were fractured transversely, horizontally, and parasagittally, and the intrasomitic cellular arrangement pattern was examined with the sem. it was found that ambystoma and pleurodeles ...	1981	7338706
the ability of localized implants of whole or minced dermis to disrupt pattern formation in the regenerating forelimb of the axolotl.	the ability of localized grafts of dermis to alter pattern formation in the regenerating limb of the axolotl was studied. longitudinal pieces of skin (1/4 of circumference of the limb) were removed from either the anterior or the posterior surface of the upper forelimb. epidermis was removed by immersion in versene followed by mechanical stripping. the resulting dermis was cross transplanted directly beneath the skin on the opposite side of the limb from which it originated. after 5 days of heal ...	1981	7034520
enzymes involved in dna replication in the axolotl. ii. control of dna ligase activity during very early development.		1981	7286414
enzyme involved in dna replication in the axolotl. i. analysis of the forms and activities of dna polymerase and dna ligase during development.		1981	7286413
probability aspects of supernumerary production in the regenerating limbs of the axolotl, ambystoma mexicanum.	the applicability of deterministic models, and in particular the polar co-ordinate model of french, bryant & bryant (1976), to the regenerative process has been investigated by performing ipsilateral blastemal rotations of varying angle on the fore and hind limbs of the axolotl. the results show that the frequency of supernumerary production rises with increasing angle to reach a peak at 180 degree and then falls off more rapidly, giving rise to an asymmetric distribution curve. the position of ...	1981	7334295
behavioral and electrophysiological study of cutaneous trigeminal nerves in axolotls. ii. the effects of cross-anastomosis of nerves.		1981	7272781
behavioral and electrophysiological study of cutaneous trigeminal nerves in axolotls. i. normal innervation and reinnervation following nerve section.	behavioral responses to light tactile stimulation of the skin of the head of axolotls were variable in occurrence but were of a constant pattern. retraction of the eyes and gills followed stimulation of dorsal but not ventral skin. ventral skin yielded lowering of the head. touching near the lips caused turning of the head and a snap towards the stimulator. following section and regeneration of divisions of the trigeminal vth nerve, normal behavioral responses returned in 7-17 weeks. afferent ac ...	1981	7272780
mitochondrial morphology in the spermatozoa of the mexican axolotl, ambystoma mexicanum.	thin-section and freeze-fracture electron microscopy of immature and mature spermatozoa of the mexican axolotl, ambystoma mexicanum, revealed numerous small spherical mitochondria with diameters ranging from 0.15 to 0.22 micrometers. both the spherical form and the small size of these mitochondria were confirmed by serial thin-section studies. in mature spermatozoa, the mitochondria are located in the midpiece region, in tight contact with each other, exhibiting an almost crystalline arrangement ...	1981	7320076
amphibian pronephric duct morphogenesis: segregation, cell rearrangement and directed migration of the ambystoma duct rudiment.	the axolotl pronephric duct rudiment is readily accessible to both sem observation and surgical manipulation. the rudiment segregates from the dorsal part of the lateral mesoderm and then extends caudally along the ventrolateral border of the segmenting comites, eventually contacting the cloacal wall. the marked thinning of the rudiment which accompanies this migration is paralleled by a corresponding reduction in cell number across the duct's diameter and by caudad translocation and elongation ...	1981	7310283
[effects of concanavalin a on neural induction in the young gastrula of the axolotl (ambystoma mexicanum shaw. ) and pleurodele (pleurodeles waltlii michah.)].	presumptive ectoderm from young gastrulae of the pleurodele and the axolotl was treated with concanavalin a(5-25 micrograms/ml). then, it was combined, in a sandwich, with the dorsal lip of the blastopore and cultured in vitro for 5-7 days. the results of the experiments show that the treated ectoderm becomes more fragile than untreated control ectoderm. nevertheless, the neural induction and the histological differentiation of the neural tissue appeared in a rather normal fashion.	1981	7257883
regeneration of subnormally innervated axolotl arms.	forearms of juvenile axolotls contain about 5000 axons, of which only 25% are myelinated and visible by light microscopy. virtually all the axons degenerate after transection of the brachial plexus, but repeated operations fail to keep the arm completely denervated. regrown nerve fibres were detected by electron microscopy after 6 weeks of attempted denervation and related to the quantity usually considered necessary for limb regeneration. such arms regenerated quite normally, provided their inn ...	1981	7276803
vitellogenin synthesis and characterisation of the liver estrogen receptor in the neotenous salamander ambystoma mexicanum.		1981	7227646
two actin variants in developing axolotl heart.		1981	6894432
[autoradiographic investigations on postnatal proliferative activity of the telencephalic and diencephalic matrix-zones in the axolotl (ambystoma mexicanum), with special references to the olfactory organ (author's transl)].	the localization and proliferative activity of the matrix-zones has been investigated in the telencephalon and in the diencephalon of 21 axolotls (ambystoma mexicanum) by means of autoradiographs, after injection of tritiated thymidine at different stages of the postnatal life. there are no previous detailed autoradiographical reports on postnatal brain development in the axolotl. matrix-zones (i.e. ventricular and subventricular zone) exist in the dorsal part and in the ventral part of the tele ...	1981	7336815
antigen trapping in ambystoma mexicanum. role of secondary lymphoid organs.		1981	7238968
comparative immunocytochemical localization of prolactin and somatotropin in the pituitaries of lepidosiren paradoxa, rana temporaria and ambystoma mexicanum.	the cellular binding sites of anti-oprl igg and anti-bsth igg were demonstrated in the pituitary glands of lepidosiren paradoxa, rana temporaria and ambystoma mexicanum by means of the unlabeled antibody enzyme method by light and electron microscopy (the latter only in lepidosiren). with the light microscope prl or prl-like substances and sth or sth-like substances were revealed in two different cell types in the distal lobe corresponding to the acidophils. however, as a result of the insuffici ...	1981	7018691
lactate dehydrogenase isoenzyme pattern as a marker of lymphocyte populations in the axolotl (ambystoma mexicanum).		1981	6976277
thymus dependency in anti-trinitrophenyl (tnp) binding responses in the spleen of ambystoma mexicanum. effects of thymectomy and anti-thymocyte serum treatments.		1981	6970685
the movement of the prospective eye vesicles from the neural plate into the neural fold in ambystoma mexicanum and xenopus laevis.		1981	7286445
[histochemical study of the cholinesterases of various formations of the vertebrate endbrain].	histochemical studies have been made on true (ache) and false (bche) cholinesterases in different parts of the telencephalon of amphibians, reptiles and mammals. the data obtained indicate that the enzymic localization depends on both the level of the development of the brain and phylogenetic age of its individual formations. in the telencephalon of ambystoma mexicanum, high concentration of ache was found in vascular-capillary network, in other investigated amphibians (triturus vulgaris, rana t ...	1981	6976662
regulation of antibody synthesis in the x-irradiated mexican axolotl.	the effects of x-irradiation were studied on the mexican axolotl antibody synthesis. to reduce the anti-horse red blood cell (hrbc) antibody titers, 150 rd and smaller doses are ineffective, 200-450 rd are increasingly effective, and 700 rd are maximally effective (and lethal). a significant enhancement of the anti-hrbc titers was observed in low doses (50-150 rd x-irradiated animals). this enhancement was also observed when a low x-ray dose was applied only on the thymic areas. in whole body, b ...	1981	7028489
equilibrium properties of a voltage-dependent junctional conductance.	the conductance of junctions between amphibian blastomeres is strongly voltage dependent. isolated pairs of blastomeres from embryos of ambystoma mexicanum, xenopus laevis, and rana pipiens were voltage clamped, and junctional current was measured during transjunctional voltage steps. the steady-state junctional conductance decreases as a steep function of transjunctional voltage of either polarity. a voltage-insensitive conductance less than 5% of the maximum remains at large transjunctional vo ...	1981	6259274
identification and morphometric evaluation of the synapses of optic nerve afferents in the optic tectum of the axolotl (ambystoma mexicanum).	ther terminals of retinal afferents in the tectum of the axolotl have been identified ultrastructurally using techniques of horseradish peroxidase-filling and degeneration. the mitochondria in filled structures show a characteristic electron-lucent matrix. after both eyes have been removed, terminals with light mitochondria disappear from the area known to receive an optic input. in this area the presence of light mitochondria is almost always diagnostic of the retinal origin of a bouton. the sy ...	1981	7214469
has prolactin an intermedin-like activity on the integument of the axolotl?	skin explants of the neotenic form of ambystoma tigrinum (axolotl) have been kept in culture during several days. when alpha-msh or prolactin are added to the medium, a dispersion of melanin in melanosomes is observed. the reaction is reversible in the case of prolactin when the explants are transferred in the medium without hormones. furthermore with prolactin, expansion of melanin in dermal melanophores is a more permanent and highly reproducible phenomenon, compared with the action of alpha-m ...	1981	6176199
the serotonergic somatosensory projection to the tectum of normal and eyeless salamanders.	the spinotectal somatosensory projection was compared in normal, genetically eyeless, and embryonically manipulated salamanders. in normal animals, serotonin fluorescence was restricted to the intermediate tectalneuropil. this same region showed both high levels of serotonin uptake and somatosensory single unit electrical activity. in mutant eyeless salamanders and in normal animals enucleated early in development, serotonin fluorescence, serotonin uptake, and somatosensory activity were present ...	1981	30153710
constant occurrence of an ipsilateral retino-tectal projection in the axolotl (ambystoma mexicanum) revealed by horseradish peroxidase tracing.	cut optic nerves were filled orthogradely with horseradish peroxidase (hrp) to reveal contralateral and ipsilateral retino-tectal projections in the axolotl, by light and electron microscopy. the ipsilateral projection is small but consistently present. it is concentrated in the rostral tectum particularly the dorsomedial and ventrolateral areas. the results are compared with findings in other vertebrates.	1980	7052461
lysophosphatidyl choline facilitates labeling of cns projections with horseradish peroxidase.	previously, it has been difficult to label sensory terminations in the cns by back-filling peripheral sensory nerves with horseradish peroxidase (hrp), apparently because the amount of hrp transported along the axons is insufficient. labeling of central sensory projections in axolotls and frogs can be improved by agents known to disrupt membranes. of those tested, l-alpha-lysophosphatidyl choline is the most effective. the addition of this detergent ot the hrp solution dramatically increases bot ...	1980	6967137
an interaction between dorsal and ventral regions of the marginal zone in early amphibian embryos.	when small explants from early gastrulae of xenopus laevis are allowed to develop in a buffered salt solution there is a considerable difference between the patterns of differentiation obtained from different dorsoventral levels of the marginal zone. these patterns of differentiation correspond to the fates of the different regions in the course of normal development. they are not altered if several explants of the same type are fused before culture. if a ventral marginal zone explant from xenop ...	1980	7400747
dominant lethal induction by ethyl methanesulfonate in the male axolotl (ambystoma mexicanum).	when male axolotls (ambystoma mexicanum) were treated with ethyl methanesulfonate (ems) and mated at regular intervals thereafter, the incidence of embryonic abnormalities among the f1 progeny increased until a time was reached when none survived to hatching. at 100 mg/1 ems, this point was reached about 130 days after treatment. thereafter, the frequency of abnormalities gradually decreased to control levels. at higher concentrations, abnormalities were seen in spawnings obtained sooner after t ...	1980	7462966
an atlas of notochord and somite morphogenesis in several anuran and urodelean amphibians.	a scanning electron microscopic, comparative survey of notochord and somite formation including some details of change in cell morphology and arrangement, was made of selected stages of two species of anuran amphibians (xenopus laevis and rana pipiens) and two species of urodeles (ambystoma mexicanum and pleurodeles waltlii). the ectoderm or neural plate was removed from fixed embryos and the dorsal aspect of the developing notochord and somite mesoderm was photographed. micrographs of comparabl ...	1980	6971322
survey of the numbers and species of amphibia used in the united kingdom in 1977.	this survey suggests that about 115 000 amphibia, of which more than half were rana temporaria, were supplied for use in teaching and research in the uk during 1977. as only 27 000 were recorded as being used by universities, polytechnics and research institutes, probably mostly for teaching, it must be assumed that the majority are used for teaching purposes in schools. there has been an increase in the proportion of amphibia supplied by recognised suppliers, and also in that being 'purpose-bre ...	1980	6965743
pattern regulation and the origin of extra parts following axial misalignments in the urodele limb bud.	pattern regulation following axial misalignments in the stage-38+to stage-40 urodele limb bud was studied on one newt and two salamander species. grafts of the distal tip of the limb bud were made to the stump of a host limb bud from which a similar piece had been removed. the grafts were positioned with either their anteroposterior, dorsoventral, or both of these axes reversed with respect to the host axes. mirror-imaged duplications, positioned posteriorly or both anteriorly and posteriorly, o ...	1980	7310274
evidence that the premature death mutation (p) in the mexican axolotl (ambystoma mexicanum) is not an autonomous cell lethal.	cell-lethal developmental mutations, which are presumed to affect the viability of all cells in a mutant embryo, have been distinguished from other development lethals on the basis of the results of parabiosis and transplant experiments. premature death (p), previously classified as a cell lethal, does not survive parabiosis. however, transplants involving mutant eye, flank epidermis and primordial limb tissue all survived on a normal recipient. the mutant, therefore, cannot be considered a true ...	1980	7310271
regions of the brain influencing the projection of developing optic tracts in the salamander.	eye primordia from the mexican axolotl or the california newt were transplanted into hosts of either species. these "third" eyes often developed an optic nerve that penetrated the host brain and made one of three central projections: bilateral to the dorsal thalami, tecta, and basal optic nuclei; ipsilateral to the same areas; or ipsilateral into the cord. the type of projection made by a transplanted eye seemed to depend on where its nerve first entered the brain. the optic fibers that reached ...	1980	7440804
the effects of eliminating impulse activity on the development of the retinotectal projection in salamanders.	the california newt taricha torosa manufactures tetrodotoxin, a blocker of voltage-sensitive sodium channels and therefore of action potentials.the newt's own nervous system is insensitive to this toxin. grafting an embryonic eye to the newt from a tetrodotoxin-sensitive species, the mexican axolotl, blocks action potentials in the retinal ganglion cells of the transplanted eye. neuroanatomical and electrophysical techniques demonstrate that while such ganglion cells are incapable of firing impu ...	1980	7440803
cell commitment and gene expression in the axolotl embryo.	in the axolotl embryo the somitic mesoderm passes through a reversible and then an irreversible phase of commitment with respect to its later differentiation into muscle. we show that the commencement of alpha-actin synthesis and the first appearance of thin myofilaments occur at the the same developmental stage as the transition between these phases. in intact embryos beta-and gamma-actin are made at all stages of development and in all tissues. alpha-actin, however, first appears at the late h ...	1980	6893572
segmental innervation of rotated and supernumerary axolotl hindlimbs.	the segmental nerve supply to axolotl limbs was misrouted by severing the limbs at the level of the femur, rotating them 180 degrees around their long axis, and then suturing them to the intact proximal stump. following return of the blood supply to the rotated limb by the cross-anastomosing of blood vessels, a blastema often formed to the side of the rotation site giving rise to a supernumerary limb. the muscles of both rotated and supernumerary limbs were innervated by the segmental nerves. th ...	1980	7462973
intercalary regeneration of symmetrical thighs in the axolotl, ambystoma mexicanum.		1980	7000578
suppression of sprouted synapses in axolotl muscle by transplanted foreign nerves.	1. the supracoracoideus (s.c.) muscle of the axolotl shoulder is innervated by two nerves, the anterior and posterior s.c. nerves. the posterior nerve was induced to make synapses outside its normal territory in the muscle by removing a segment of the anterior nerve. intracellular recording indicated that the efficacy of transmission from posterior nerve terminals outside their normal territory increased over several weeks prior to the return of the anterior nerve. 2. the anterior nerve reinnerv ...	1980	6259337
morphogenetic properties of the skin in axolotl limb regeneration.	a study has been made of the morphogenetic properties of anterior and posterior skin from the lower forelimb of the axolotl. the basic experiment consisted of a graft of a half cuff of skin from a donor to a host limb followed by a 2-week healing period, amputation through the graft, and a study of the resulting regenerate. limbs with double posterior skin formed double posterior regenerates and, in contrast, limbs with double anterior skin formed normal or slightly hypomorphic regenerates. post ...	1980	7003051
inducing effects of the grey crescent region of early developmental stages of ambystoma mexicanum.	parts of the grey crescent region of 1-2 cell, 8 cell and morula stages ofambystoma mexicanum were combined with presumptive gastrula ectoderm of the same species (sandwich method).grey crescent material of the early cleavage stages induced neural tissues at a very low rate (6%-7%).from the morula stage onwards, the inducing ability of the grey crescent area increased and led to the formation of mesodermal as well as neural organs. the implanted area did not participate in the organ formations.	1980	28304975
regulation and potency in the forelimb rudiment of the axolotl embryo.	anterior, posterior, dorsal and ventral halves of the pre-bud forelimb rudiment of tail-bud axolotl embryos can all give rise to normal limbs after the complementary half has been removed. a histological study of the regulation of the posterior half rudiment showed no requirement for mesodermal healing across the gap, and no proliferative zone. the development of the limb bud on the operated side lags behind that of the control bud for several weeks of larval life. when half limb rudiments and d ...	1980	7430930
experiments on developing limb buds of the axolotl ambystoma mexicanum.	various experiments were performed on the limb buds of axolotls to compare the behaviour of amphibian limbs with that previously reported for chick limbs. following removal of the tip or whole limb bud, extensive powers of regulation were observed since complete limbs always formed. similarly after distal to proximal grafts intercalary regulation occurred to produce perfect limbs and after proximal to distal grafts serial repetitions resulted. transplantation and rotation of limb buds to reverse ...	1980	7430928
gap junctions in early amphibian embryos.	cell pairs from late cleavage and early blastula ambystoma mexicanum embryos were found to be electrotonically coupled. thin-section electron microscopy revealed typical gap junctions between the cells. freeze-fracture electron microscopy showed the gap junctions to be comprised of aggregations of 8.5-nm p-face particles and corresponding e-face pits. the conductance of the amphibian embryonic gap junction is known to be voltage-dependent, but no obvious gating structure was resolved by these mo ...	1980	7416050
ultrastructure of the renal juxtaglomerular complex and peripolar cells in the axolotl (ambystoma mexicanum) and toad (bufo marinus).	renal juxtaglomerular regions were examined in the axolotl (ambystoma mexicanum and toad (bufo marinus). prominent granulated peripolar epithelial cells were found surrounding the origin of the glomerular tuft in the axolotl. these cells resembled the peripolar cells recently discovered in mammalian species. they contained multiple electron-dense cytoplasmic granules, some of which showed a paracrystalline substructure and signs of exocytoxic activity. such cells were difficult to find and small ...	1980	7410189
regeneration of reversed aneurogenic arms of the axolotl.	aneurogenic arms of young axolotls were implanted into the flank as heterotopic autografts with reversed proximo-distal orientation. the formerly proximal ends of such arms regressed to a variable extent, and then either regenerated or could do so following a second amputation. the regenerate always contained a complete sequence of skeletal elements between the adjacent stump skeleton and terminal digits, being a mirror image of the implanted arms with identical transverse axes but an opposed pr ...	1980	7400749
spatial distribution of abundant proteins in oocytes and fertilized eggs of the mexican axolotl (ambystoma mexicanum).		1980	7372013
neural crest cell migration in relation to extracellular matrix organization in the embryonic axolotl trunk.		1980	7371990
electrical activity in cardiac mutant axolotl hearts.	electrical recordings from the hearts of both cardiac lethal mutant and normal embryos showed the presence of action potentials conducted over the heart tube. ionic coupling and gap junctions also were observed in both. these results suggest that the absence of heart function in mutant embryos does not result from a defect in electrical activity.	1980	7373269
distal transformation from double-half forearms in the axolotl, ambystoma mexicanum.		1980	7371978
regeneration of symmetrical forelimbs in the axolotl, ambystoma mexicanum.		1980	7371977
melanogenesis in oocytes of wild-type and mutant albino axolotls.		1980	7371975
hemoglobins of an amphibia, the neotenous ambystoma mexicanum. complete amino-acid sequence of the alpha chain of the major component using automatic solid-phase edman degradation.	the primary structure of axolotl (neotenous ambystoma mexicanum) alpha chain has been determined. nh2-terminal sequence data were performed using the solid-phase method. complete amino acid assignments were deduced from the sequences of peptides obtained after cleavage with cyanogen bromide; the methionine-containing peptides, isolated from alpha chain tryptic digest, allowing the alignment of these fragments. all overlaps have been clearly established. axolotl alpha chain contains 142 residues, ...	1980	7358052
immunofluorescence studies for myosin, alpha-actinin and tropomyosin in developing hearts of normal and cardiac lethal mutant mexican axolotls, ambystoma mexicanum.	recessive mutant gene c in axolotl embryos results in an absence of normal heart function. immunofluorescence studies were done to determine the distributions of myosin, tropomyosin and alpha-actinin in the hearts of normal and mutant siblings. anti-myosin specifically stains the a bands of myofibrils in normal hearts and reveals a progressive increase in myofibril organization with development. mutant hearts display less staining for myosin than normal and localization is mainly in amorphous co ...	1980	6989943
neural crest replaced by gastrula ectoderm in amphibia. effect on neurulation, cns, gills and limbs.	early axolotl gastrula ectoderm was grafted into early triturus neural stages in place of excised neural folds at the gill and anterior trunk level. macroscopically the young graft behaves like normal neural fold material: it follows the closing host neural plate to the dorsal midline, folds into the host's interior and, especially in the gill region, moves ventrad beneath the host's epidermis. these movements cannot be interpreted as active migration. they are the result of passive displacement ...	1980	7457916
evidence of the first genetic activity required in axolotl development.		1980	7444204
on spontaneous skin tumours in amphibia.	in 7 from 320 rana temporaria grass frogs and 16 from 978 rana ridibunda pond frogs, the 31 and 47 spontaneous skin tumors respectively, were observed. the tumors were represented by cystadenopapillomas and adenocarcinomas, and developed from epithelium of skin mucous glands. the spontaneous pigment tumors (melanophoromas) were found in 2 axolotls ambistoma mexicanum. these tumors developed from hyperplastic melanophores in pigment spots and focal proliferations of melanophores located deeply in ...	1980	6969862
evidence for a dna ligase change related to early cleavage in axolotl egg.	a definite change in the forms of dna ligase appears when the axolotl egg enters cleavage. sucrose gradient and phosphocellulose chromatography show that the a 6s form of dna ligase exists before division, i.e. in unfertilised and fertilised egg, and a 8.2s form is present at the first division. n-ethylmaleimide sensitivity and heat stability are different for the two forms. the possible significance of this early change is discussed.	1979	574805
the formation of muscles in regenerating limbs of the newt after denervation of the blastema.	the purpose of this experiment was to examine the relationship, if any, between nerve fibers and the formation of muscle pattern in the regenerating amphibian limb. during embryogenesis, nerve fibers grow into the limb bud at the time when the common muscle blastemas subdivide into individual muscle primordia, whereas in regeneration nerve fibers are always present. in order to learn whether or not the muscle pattern could be laid down in the absence of nerves we amputated 58 limbs of newts (not ...	1979	528874
positional information in the forelimb of the axolotl: experiments with double-half tissues.		1979	527764
steroidogenesis in axolotl testis. histochemistry of two major enzymes related to cell type, spermatogenesis, and substrate.		1979	499762
target recognition in neurogenesis: formation of the mauthner axon cap.	to learn whether presence of a specific neuron, the mauthner (m) cell, is required for the organization, during embryogenesis, of an associated synaptic neuropil, the m-axon cap, m-cell precursors were experimentally deleted in embryos of the zebra fish (brachydanio rerio) and the axolotl (ambystoma mexicanum). examination of early larvae revealed that in about half of the cases m-axon caps were present in the absence of the corresponding m-cells. the locations and structures of such caps were a ...	1979	291997
dna synthesis after polyspermic fertilization in the axolotl.	cytological and autoradiographic studies were done to investigate the cytoplasmic control of dna synthesis under conditions of physiological polyspermy. the dna synthetic phases of the egg, principal sperm and accessory sperm nucleic were determined and correlated with nuclear morphology and develpmental fate. results show that accessory sperm nuclei undergo morphological transition to pronuclei. their dna synthetic phase is the same as that of the principal sperm nucleus. hence accessory sperm ...	1979	574896
multiple melanomas in the axolotl ambystoma mexicanum.	multiple melanophoromas in the axolotl ambystoma mexicanum were characterized by cell anaplasia and polymorphism. pigment spots may be the first stage of tumor development.	1979	286820
normal anterior endoderm corrects the heart defect in cardiac mutant salamanders (ambystoma mexicanum).	recessive mutant gene c in axolotl embryos results in an absence of heart function. normal (+/+) anterior endoderm cultured with mutant (c/c) hearts totally corrects the defect.	1979	441740
an sem and tem study of suppression of eye development in eyeless mutant axolotls.	morphology of the primary optic rudiment of normal eyed and mutant eyeless (e/e) axolotl embryos was studied at light. tem and sem levels. the presumptive eyeforming region of eyeless embryos differs from that of normal embryos in several important respects including premature formation of basal lamina, separation from overlying ectoderm by mesenchyme cells and persistence of granules in the interspace surrounding the optic anlage into relatively late developmental stages. these differences sugg ...	1979	110173
maintenance of growth- and thyroid-stimulating properties of ectopic pituitaries in the mexican axolotl (ambystoma mexicanum).		1979	467973
chloride-dependent sodium transport in the skin of ambystoma mexicanum [proceedings].		1979	458718
axon reflexes in axolotl limbs: evidence that branched motor axons reinnervate muscles selectively.		1979	428494
regenerative responses in larval axolotl limbs with skin grafts over the amputation surface.	complete flaps of whole skin over the amputation surface of larval axolotl limbs did not prevent dedifferentiation, dna synthesis, and mitosis. however, even by two weeks, insufficient cell division had occurred for blastema formation. in about 50% of the cases, small areas of wound epidermis formed over the amputated tip of the radius or ulna. at two weeks after amputation, mitotic figures and dedifferentiated cells which incorporated h3-thymidine were predominantly located in the vicinity of t ...	1979	381569
development of synaptic connections between different segmental motoneurones striated muscles in an axolotl limb.		1979	446887
[experimental studies on the symmetry reaction of axolotl oocytes and eggs: factors affecting the early appearance of the grey crescent following heat shock].	a heat-shock (36.8 degrees c for 10 min.) can induce the immediate appearance of the grey crescent in a high proportion of freshly laid fertilised or artificially activated axolotl eggs, but only if that shock occurs within 1 h 30 min. following deposit of eggs (at 18 degrees c) and if eggs are not dejellied. on non-activated virgin eggs, the heat-shock is efficient during at least 3 hrs. this symmetry reaction can be induced on in vitro artificially matured oocytes, still protected by follicula ...	1979	111864
suppression of foreign innervation in axolotl muscle may not be dependent on juxtaposition of native and foreign nerve terminals.	the posterior supracoracoideus nerve of the axolotl, ambystoma mexicanum, was induced to make synapses outside its normal muscle territory. muscle fibres with inputs from both native and foreign nerves were studied during the period of suppression of foreign transmission and in only 8% of fibres were foreign and native terminals found within 120 micrometer of each other. a combined cholinesterase/silver staining technique revealed non-innervated endplates in foreign-innervated fibres just prior ...	1979	223086
duplicated axolotl regenerates.	three series of palette stage regenerates were prepared by amputating both arms of juvenile axolotls in the mid-forearm, above the elbow, or close to the shoulder. within each series, excised regenerates were replaced in their original orientation (as a control) or rotated at 90 degrees intervals about the proximodistal axis, or were transplanted to the contralateral arm with identical rotations. control grafts occasionally caused the formation of a single extra digit. all experimental rotations ...	1979	448271
morphogenetic interactions occurring between blastemas and stumps after exchanging blastemas between normal and double-half forelimbs in the axolotl, ambystoma mexicanum.		1979	437319
delayed hypersensitivity in ambystoma mexicanum.		1979	113261
[invariability of the h-y antigen expression in the heterogametic sex of some amphbians and evidence for sexual dimophrism of the antigen expression in pelodytes punctatus d (amphibia, anura)].	the h-y antigen is studied in some amphibians whose sexual genetic constitution is known. thus, in pelurodeles waltlii, ambystoma mexicanum, xenopus laevis and rana ridibunda, the invariability of the h-y antigen expression in the heterogametic, sex is confirmed. in pelodytes punctatus the genetic sex is unknown but the existence of the h-y antigen in phenotypic males leads to the conclusion of a male heterogamety of the xy type.	1979	121269
thymus independent anti-horse erythrocyte antibody response and suppressor t cells in the mexican axolotl (amphibia, urodela, ambystoma mexicanum).	anti-horse erythrocyte (anti-hrbc) antibody synthesis was studied in normal, early thymectomized and adult thymectomized axolotls. the kinetics of the responses were similar to those described in the same species for antibody synthesis against bacterial or viral antigens. booster injections did not induce any characteristic anamnestic responses. early and adult thymectomized axoltls gave in three experimental groups higher anti-hrbc responses than controls. it is concluded that hrbc acts in the ...	1979	312266
role of tropomyosin in actin filament formation in embryonic salamander heart cells.	recessive mutant gene c in ambystoma mexicanum embryos causes a failure of the heart to function even though initial heart development appears normal. an analysis of the constituent proteins of normal and mutant hearts by sds-poly-acrylamide gel electrophoresis shows that actin (43,000 daltons) is present in almost normal amounts, while myosin heavy chain (200,000 daltons) is somewhat reduced in mutants. both sds-polyacrylamide gel electrophoresis and immunofluorescence studies reveal that tropo ...	1979	383724
the regression of synapses formed by a foreign nerve in a mature axolotl striated muscle.	a study has been made of the factors which determine that the terminals of a foreign flexor nerve at synaptic sites in a unrodele extensor muscle regress on return of the original extensor nerve. the quantal content (m) of the endplate potential (epp) at flexor nerve terminal synapses, during innervation of a previously denervated extensor muscle, increased in about 8 weeks to reach the same size as at normal extensor nerve terminals; the same time was taken for m to reach normal size at extenso ...	1979	487102