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At least 55 records · Page 3Linked to original sources
PubMed1990

[Cranial morphology of an American siphonopid, Microcaecilia unicolor (Amphibia, Gymnophiona) and its functional interpretation].

The skull of Microcaecilia unicolor, american Siphonopidae (Amphibia, Gymnophiona), shows 3 notable morphological characteristics: The mandibular shortening, the verticalization of the retroarticular process, and the verticalization of the quadrate. They define a peculiar morphofunctional pattern, which seems to exist in dwarf forms moving in the complex root system of trees. These morphological characters, associated with modifications of the muscle depressor mandibulae, give functional advantages: A wider gaping of the mouth and the ability of the ingestion of preys which have a great cross-section. In keeping its macrophageous habits, Microcaecilia unicolor does not compete with other dwarf vertebrates living in the same environment and feeding on microinvertebrates.

Amphibians↗
PubMed1989

[Asymmetry of the habenular nuclei during ontogenesis in Pleurodeles waltl (Amphibia, Urodela)].

Qualitative and quantitative studies of the habenular nuclei in Pleurodeles waltl (Amphibia, Urodela) were done. Histological and cytological differences are shown between left and right habenula, the latter being smaller and located more caudal than the former. The right habenula is not as differentiated as the left one whose dorsal part can be subdivided in two parts: medialis and lateralis. A quantitative study of each habenula was undertaken using an automatic analyser system. The result shows that the differentiation into dorsal and ventral populations, appears later in the right habenula (stage 48) than in the left one (stage 36).

Animals↗
PubMed1977

[Ultrastructural features of ureter-mesenchyme interaction, during nephrogenic induction in Amphibia].

Transmission electron microscopy was used to study the interface between the ureter and the mesonephric blastema. When the blastema is induced in a functional organ, numerous pseudopodial protrusions of the ureter and of the mesonephric cells lead to a close appostion between the two structures. The presence of squamous material, perhaps of a mucopolysaccharidic nature, with a network of collagen fibres is always found on this interface. These particular processes seem to play a role as a morphological basis for the phenomenon of induction. The importance of the extracellular matrix is discussed. Neither the occurrence of zones of close contact, reported by several authors, in other species, nor the fusion of membranes has ever been observed in Amphibia.

Animals↗
PubMed1979

[Enzyme histochemical study of the brain of Chthonerpeton indistinctum (Gymnophiona, Amphibia)].

In the brain of the Caecilian species Chthonerpeton indistinctum the following enzymes have been demonstrated by means of histochemical techniques: acid phosphatase, alpha-naphthylacetate esterase, acetylcholin esterase. Acid phosphatase occurs in the cytoplasm of the neurons in 4 different types of localization. Its activity in the ventral parts of the brain is markedly higher than in the dorsal ones. Of particularly high activity are: the motor neurons in the tegmentum, the nucleus mesencephali trigemini, individual large neurons in the marginal zone of the grey matter of the telencephalon, which seems to be a special character of the Caecilians among the Amphibia. The ependyma exhibits local differences in respect of acid phosphatase activity. alpha-Naphthylacetate esterase marks in particular the secretory neurons of the hypothalamus, the large perikarya of the nucleus mesencephali trigemini and the motor neurons of the tegmentum. In the telencephalon the alpha-naphthylacetate esterase activity corresponds to that of acid phosphatase. Acetylcholin esterase marks--with certain restrictions--cholinergic neurons. These predominate in Chthonerpeton in the caudal parts of the brain. In the telencephalon amygdala, septal area striatum and the mitral cells are of comparatively high activity. The neurosecretory neurons of the hypothalamus are particularly rich in this enzyme. As an anurans the cholinergic fasciculus retroflexus as asymmetric. The tectum opticum is of secondary simplicity and does not exhibit a clearly recognizable stratification.

Acetylcholinesterase↗
PubMed1980

[Cytologic and ultrastructural organization of the kidney tubules of certain amphibia].

As the investigation performed demonstrated, there is no principle differences in cytological organization in kidneys of five species of Amphibia whose mode of life to a certain extent is connected with water environment. Nevertheless, in different species epithelium of proximal parts of nephrons demonstrates various intensity of apocrinic secretion. Granules situating in the supranuclear zone of the epithelial cells of these parts are, in fact, autophagic lysosomes, their function is evidently connected with both lysis of the absorbed proteins and with autolysis of the apical cellular part in the process of secretion. The epithelial cytoplasm in the distal part of the nephron is characterized by a high succinate dehydrogenase activity; it is connected with its main function--osmoregulation. There are dark and light cells, resembling those in higher vertebrates, in the connecting part and in the collecting tubes. Ultrastructural organization of the brown frog nephron cells has much in common with that of epithelium of the secondary kidney urinary canaliculi.

Animals↗
PubMedDate not supplied

Effects of carcinogens on regenerating and non-regenerating limbs in amphibia (review).

The effects of chemical carcinogens on regenerating and non-regenerating limbs in amphibia are reviewed. The regeneration-competent tissues show a remarkable resistance to chemical carcinogenesis. However, chemical carcinogens can induce teratogenesis when they are administered to the regeneration blastema, while normal differentiation occurs in limited cases when they are administered to the intact limbs. The regenerative capacity may be considered as the deterrent to neoplasia in these tissues.

Abnormalities, Drug-Induced↗
PubMed1983

[Experimental anatomic study of the topography of the retinofugal projections in Discoglossus pictus (Amphibia, Anura). I. The thalamus: re-examination of the contralateral retinotopy and the origin of the uncrossed optic fibers].

The topography of retinofugal projections on the thalamus of an Anuran Amphibia was studied by Fink-Heimer technique. After small lesions in retina, degeneration was found in all contralateral neuropils and in one or several ipsilateral neuropils according to retinal location: A lesion in temporal retina is followed by large axonal degeneration in neuropil of Bellonci; a dorsal lesion invaded whole geniculate neuropil while within it, contralateral ventral and nasal projections are scarce. Ipsilaterally, excepted for the nasal retina, all territories project to anterior neuropils; but, only temporal fibres ended in ipsilateral pretectal neuropil. The incinate neuropil receives bilateral projections from the whole retina. This study shows that, rather than a strict segregation, an overlap of quadratic projections into the same neuropil and a divisional repartition of these projections between the two anterior neuropils seem to be the rule.

Animals↗
PubMed1983

[Experimental anatomic study of the topography of the retinofugal projections in Discoglossus pictus (Amphibia, Anura). II. The tectum: existence of a double-system of primary optic projections].

The possibility of retinotopic organization of bilateral retinotectal projection was studied by fotal retinal lesions followed by the Fink-Heimer technique. This work in Discoglossus pictus (Amphibia, Anura) shows two types of direct visual projections: a contralateral projection within the tectal layer 9 and a bilateral projection on tectal layer F of Potter (1969). The ipsilateral projection within tectal layer 9, earlier described after enucleation (Picouet et Clairambault, 1977), is not observed here. We discuss about reasons we failed to reveal it. Although appearing to be grossly in accord with data of literature, the retinotopic pattern of "classical" retinotectal projection (on layer 9) of Discoglossus presents some differences as the overlap of quadratic retinal projections. The anatomical tectal retinotopy appears less precise that physiologic retinotopy. The bilateral projections on layer F are characterised by medial (and specially medioposterior) location and the complete absence of retinotopy. All lesions in different parts of retina lead degeneration which take place in a series of distinct loci in the dorsal layer F. We discuss about a possible participation of axial optic tract to this projection.

Animals↗
PubMed1981

Comparative acid phosphatase distribution in the suprarenal gland of Discoglossus pictus, Xenopus laevis and Bufo bufo (Anurans, Amphibia).

Acid phosphatase activity was found to have a similar distribution in the suprarenal glands of Discoglossus pictus, Xenopus laevis and Bufo Bufo (Anurans, Amphibia) as determined by light and electron histochemical localization. The enzymatic activity is localized in the lysosomes of both the interrenal cells and the chromaffin cells. It is, moreover, positive on the granule membranes of the adrenaline cells whereas it appears only occasionally on the granule membranes of the noradrenaline cells. Some precipitates can also be seen occasionally at the level of the Golgi membranes.

Acid Phosphatase↗
PubMed1981

[Study of the catecholamines in the notochord of Anura Amphibia embryos. Its possible relationships with the adenyl-cyclase activity and the primordial germ cells migration (author's transl)].

Notochord from several Anura Amphibia embryos was investigated by cytochemical study. A green fluorescence was observed, indicating a catecholamine storage in the notochord, during a precise time of their development. A stimulation of the mesoblast area by catecholamine is suggested by the analogy between the catecholamine chordal distribution and the adenyl-cyclase activity of the chordo-mesoderm. This stimulation would be followed by a cAMP production directing the PGC migration. Treatment by L-dopa increases fluorescence in the notochord. Reserpine and alpha-methyl-paratyrosine decreases the notochord fluorescence, either by stocked catecholamine depletion in the case of reserpine, or by inhibition of their synthesis by alpha-methyl-para-tyrosine.

Adenylyl Cyclases↗
PubMed1981

The telencephalon of Ichthyophis paucisulcus (Amphibia, Gymnophiona (= Caecilia)). A quantitative cytoarchitectonic study.

A parcellation of the telencephalon of Ichthyophis paucisulcus (Amphibia, Gymnophiona (= Caecilia) has been performed with a quantitative cytoarchitectonic method. Ten different regions have been delineated and compared with earlier reports on telencephalic regions in anurans, urodeles and caecilians. The most striking difference between the brain of Ichthyophis and other amphibian brains is the high level of morphological differentiation of the accessory olfactory bulb in Ichthyophis and the large extension of this brain region. This feature may be a correlate of the advanced development and the particular structure of Jacobson's organ in this species.

Amphibians↗
PubMed1994

Evolution of alanine:glyoxylate aminotransferase 1 peroxisomal and mitochondrial targeting. A survey of its subcellular distribution in the livers of various representatives of the classes Mammalia, Aves and Amphibia.

As part of a wider study on the molecular evolution of alanine:glyoxylate aminotransferase 1 (AGT1) intracellular compartmentalization, we have determined the subcellular distribution of immunoreactive AGT1, using postembedding protein A-gold immunoelectron microscopy, in the livers of various members of the classes Mammalia, Aves, and Amphibia. As far as organellar distribution is concerned, three categories could be distinguished. In members of the first category (type I), all, or nearly all, of the immunoreactive AGT1 was concentrated within the peroxisomes. In the second category (type II), AGT1 was found more evenly distributed in both peroxisomes and mitochondria. In the third category (type III), AGT1 was localized mainly within the mitochondria with much lower, but widely variable, amounts in the peroxisomes. Type I animals include the human, two great apes (gorilla, orangutan), two Old World monkeys (anubis baboon, Japanese macaque), a New World monkey (white-faced Saki monkey), a lago, morph (European rabbit), a bat (Seba's short-tailed fruit bat), two caviomorph rodents (guinea pig, orange-rumped agouti), and two Australian marsupials (koala, Bennett's wallaby). Type II animals include two New World monkeys (common marmoset, cotton-top tamarin), three prosimians (brown lemur, fat-tailed dwarf lemur, pygmy slow loris), five rodents (a hybrid crested porcupine, Colombian ground squirrel, laboratory rat, laboratory mouse, golden hamster), an American marsupial (grey short-tailed opossum), and a bird (raven). Type III animals include the large tree shrew, three insectivores (common Eurasian mole, European hedgehog, house shrew), four carnivores (domestic cat, ocelot, domestic dog, polecat ferret), and an amphibian (common frog). In addition to these categories, some animals (e.g. guinea pig, common frog) possessed significant amounts of cytosolic AGT1. Whereas the subcellular distribution of AGT1 in some orders (e.g. Insectivora and Carnivora) did not appear to vary markedly between the different members, in other orders (e.g. Primates, Rodentia and Marsupialia) it fluctuated widely between the different species. Phylogenetic analysis indicates that the subcellular distribution of AGT1 has changed radically on numerous occasions during the evolution of mammals. The new observations presented in this paper are compatible with our previous demonstration of a relationship between AGT1 subcellular distribution and either present or putative ancestral dietary habit, and our previous suggestion that the molecular evolution of the AGT gene has been markedly influenced by dietary selection pressure.

Alanine Transaminase↗
PubMed1981

Scanning electron microscopy of the normal and denervated limb regenerate in the newt, Notophthalmus, including observations on embryonic amphibia limb-bud mesenchyme and blastemas of fish-fin regenerates.

The present work deals with the morphology of normal and denervated early limb regenerates in the newt and compares them with early limb-bud mesenchyme and blastemas of fish-fin regenerates using the three-dimensional properties of the SEM. It shows that blastemal cells are polymorphic, in contrast to those of the stump-cell population, which are fairly homogeneous and from which blastema cells are said to arise by "dedifferentiation." The appearance of cells had not changed by two days following denervation even though previous biochemical studies have detected many changes in metabolism. Longterm denervation (7 days) did result in morphological changes. A comparison between well-known cell types-myoblasts, Schwann cells, osteoblasts observed in vitro, limb-bud mesenchyme and mesenchymatous fin blastema-was carried out in order to suggest explanations for the blastema-cell polymorphism.

Amphibians↗
PubMed1992

Comparative anatomy and phylogeny of the cloacae of salamanders (Amphibia: Caudata). IV. Salamandridae.

Cloacae were examined from male and female salamanders representing 12 genera and 22 species in the Salamandridae. All female salamandrids possess numerous sperm storage glands, spermathecae, in the roof of the cloaca, but intergeneric variation exists in the occurrence of additional cloacal glands. Pleurodeles and Tylototriton possess both vent and anterior ventral glands, and secondary loss has occurred of vent glands in all other genera and anterior ventral glands in Chioglossa, Cynops, Paramesotriton, and Triturus The most highly derived cloaca occurs in Euproctus asper, in which the cloacal tube extends through a conical projection, and ventral glands secrete onto the dorsolateral surface of the projection rather than into the cloaca. Marked intergeneric variation occurs in males in conformation of the cloacal cavities and in extent of the dorsal gland. In Cynops, Euproctus, Pachytriton, Paramesotriton, Taricha, and Triturus, the pseudopenis (a broad, posteriorly projecting evagination of the dorsal roof) fills much of the cavity of the anterior cloacal chamber. In most salamandrids, distal ends of the dorsal glands occur lateral to pelvic glands in the anterior end of the cloaca, and dorsal gland tubules descend to secretory sites at the posterior end of the vent. Salamandra and Mertensiella possess a unique, bifurcated dorsal gland in which distal ends of tubules lie dorsal to the other cloacal glands, and proximal ends curve ventrally in the anterior end of the cloaca to secretory sites along the cloacal orifice. Cladistic analyses indicate that the variation in presence of anterior ventral glands is due to homoplasy. The occurrence of female vent glands, bifurcated dorsal glands, and the pseudopenis supports a phylogeny based upon non-cloacal characters.

Animals↗
PubMed1992

Ultrastructure and immunocytochemistry of the neuroepithelial bodies in the lung of the tiger salamander, Ambystoma tigrinum (Urodela, Amphibia).

Light and electron microscopy of the lungs of Ambystoma tigrinum (Urodela) revealed a relatively complex pattern of the neuroendocrine (NE) cells. In the apical parts of smaller septa single NE cells not associated with nerve fibres were covered and surrounded by pneumocytes. The larger septa possessed small areas of ciliated epithelium, in which the NE cells were grouped in a form of neuroepithelial bodies (NEB) consisting of 3-5 cells and covered by goblet cells. NE cells possessed a large nucleus with patches of condensed chromatin, clear cytoplasm, and membrane-bound vesicles of variable morphology and size, containing an electron dense interior surrounded by a lucent space. The size of these dense core vesicles (DCV) ranged from 70-140 nm, while rarely the larger ones exhibited a diameter of 300-600 nm. In some NEB a second type of NE cells was observed for the first time in an amphibian species: these cells communicated with the air space and exhibited on their surface microvilli and a single modified cilium with a 8 + 1 microtubule arrangement. Their cytoplasm contained two types of DCV: dense core granules with a diameter of 140-260 nm and vesicles 320-700 nm in diameter with a moderately electron dense interior. The NEB were associated with intracorpuscular, sensory nerve terminals morphologically afferent and efferent. By immunocytochemistry, the NE cells revealed the presence of serotonin, met-enkephalin, and leu-enkephalin. A paracrine and chemoreceptor role is proposed for NEB of Ambystoma tigrinum.

Ambystoma↗