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At least 775 records · Page 43Linked to original sources
PubMed1979

Morphology, histochemistry and biochemistry of the oviduct of the toad, Bufo vulgaris (Anura, Amphibia), during the annual reproductive cycle.

On the basis of histological and histochemical characteristics the oviduct of adult Bufo vulgaris can be separated into six zones. These characteristics include mainly the relative abundance of secretory and ciliated epithelial cells, mucosal foldings, tubular glands and the staining properties of the secretory elements. The VI zone (uterine segment) is totally deprived of tubular glands and is profoundly rich in epithelial secretory cells. These cells and the tubular glands, when well-developed, are rich in neutral and acid mucins in the preovulatory phase, whereas this content is greatly diminished after ovulation. Similarly, the weight and the length of the oviduct displays a marked seasonal pattern. The same is observed for its protein content and acid and alkaline phosphatases. These parameters show the highest values in the preovulatory period and lowest after ovulation. The toad oviduct also displays marked hydroxysteroid dehydrogenase activity along the mucosal epithelium. Its functional significance remains a matter of debate, however. A marked parallelism between the present data and those obtained by others in other amphibians indicates the existence of a common pattern of seasonal modifications correlated mainly with the release of the eggs and the formation of their multi-layered coat.

Acid Phosphatase↗
PubMed1977

[Electron microscopic study of rapid morphogenetic processes in embryonic tissue explants of amphibia].

Submicroscopic rearrangements are described. They serve as the bases of rapid (up to 20 min) changes in the form of the common frog neurula explants: formation of filamentous layer under "naked" surface, appearance of lobopodia on "naked" surface, their "flow", cell polarization and submersion. In all these processes an active part appears to be played by microtubules and microfilaments the bundles of which are always oriented along the long axes of active cells or the directions of passive mechanical tensions. In the cells which are not yet polarized the microtubules form under the surface adjacent to the already polarized cell. This may be considered as one of the chains of cooperative cell polarization.

Amphibians↗
PubMedDate not supplied

[Crystallins in the differentiation and regeneration processes of the crystalline lens in amphibia].

The published and authors' data have been summarized on (1) the spectrum and properties of crystallins in different amphibian species, (2) localization and synthesis of crystallins in different cellular compartments of the adult amphibian lens, (3) dynamics of crystallin formation during embryogenesis and (4) lens regeneration from tissues of the larval and adult amphibian eyes. The necessity of more detailed studies of crystallin synthesis during embryogenesis and lens regeneration using molecular biological and biochemical methods is stressed. The significance of this approach is illustrated by the pioneering data of Soviet scientists on crystallin polypeptides and corresponding mRNAs in development of Rana temporaria obtained with the use of DNA-RNA hybridization and immunoelectroblotting.

Amphibians↗
PubMed1978

[Radioautographic analysis of from peripheral blood and a focus of inflammation in amphibia].

In the peripheral blood of intact amphibians the cells of big lymphocyte type (light-nuclear forms) only are capable to incorporate 3H-thymidine. The implantation of foreign bodies in the subcutaneous lymphatic sac of R. temporaria induced the appearance in the circulating blood of one more cell form (dark-nuclear cells) capable of DNA synthesis. The autoradiographic analysis of interrelations between these forms allows to consider them as stages of one histogenesis.

Ambystoma↗
PubMed1979

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 axolotl as a thymus-independent antigen. The enhanced response in early as well as in adult thymectomized animals can be interpreted by the presence of a suppressor T-cell activity on anti-HRBC synthesis. These results do not exclude possible thymus-dependent responses for antibody synthesis in the axolotl, although such responses were not demonstrated in urodele. The questionable lacking of some functional T-cell subsets in urodele is discussed as a working hypothesis.

Ambystoma↗
PubMed1979

[Factors influencing the changes in liver melanin content of amphibia. I. Effect of breeding temperature].

Frogs caught in winter and kept at summer temperatures, show an increase in the melanic content of the liver. Frogs caught in summer and kept at winter temperatures do not show variations in hepatic melanins with respect to the summer control specimes. This data does not correspond with the natural course of hepatic melanin fluctuations, therefore the causes of the variations are to be sought in factors other than the temperature, one of which could very probably be represented by alimentation.

Adaptation, Physiological↗
PubMed1979

[Study of factors influencing the changes in liver melanin content of amphibia. II. Effect of fasting].

Statistical examination of the data from experiments conducted on groups of Amphibians induces us to retain as plausible the hypothesis which indicates in fasting one of the preminent factors that cause an increase in the melanic content of their liver. The temperature does not act directly, but indirectly, on the process of melanosynthesis, by inducing or otherwise the semilethargous state on which alimentation depends.

Animals↗
PubMed1979

Somitogenesis in amphibia. II. Origins in early embryogenesis of two factors involved in somite specification.

A somite pre-pattern is established shortly before visible segmentation. The pre-pattern results from the interaction of two components: a wave of cell behavioural change that passes along the axis, and, an underlying co-ordination of the cells that is the basis for their association into large somite-sized groupings. The evidence is derived from studies of the zones of abnormal segmentation that follow temperature shocks delivered between the neurula and tail-bud stages (Pearson & Elsdale, 1979). Temperature shock given earlier at the mid-gastrula stage is however ineffective in inducing abnormalities in somitogenesis. Shocks given before the mid-gastrula stage reveal a prior period of sensitivity stretching back into the blastula. Thus early and late sensitive periods can be defined separated by a short refactory period. Quite different patterns in the distribution of somite abnormalities characterize the results of shock during the two sensitive periods, suggesting different aetiologies. It is concluded that the wave of rapid cell change is set up early in embryogenesis during the blastula stage, and each cell of the prospective paraxial mesoderm carries a determination to change after a specific length of time, i.e. a countdown is set in each cell. As a result of the movements of gastrulation, the prospective paraxial mesoderm cells become laid out along the axis of the neurula in the order (antero-posterior sequence) in which they will change. The achievement of the correct redistribution of the cells depends crucially on the conservation of the sequence in the blastula by the maintenance of topological integrity throughout gastrulation. It is suggested that early shock disturbs gastrulation movements, causing some mixing up of the cells resulting in incoherence of the wavefront. Whereas early shocks are thus assumed to affect the wave, the evidence suggests that late shock undergoes co-ordination. It is concluded therefore that co-ordination is established later, after the refractory period, around the late gastrula stage.

Animals↗
PubMed1988

Wakubitinema toyamai n. gen. and n. sp. (Nematoda: Seuratoidea: Quimperiidae) from the intestine of Rana (Limnonectes) Namiyei (Amphibia: Ranidae) on Okinawa Island, Japan.

Wakubitinema n. gen. (Nematoda: Seuratoidea: Quimperiidae: Quimperiinae) is erected for Wakubitinema toyamai n. sp. from the small intestine of Rana (Limnonectes) namiyei Stejneger, 1901, on Okinawa Island, Japan. Wakubitinema resembles Paraquimperia Baylis, 1934, and Desmognathinema Baker et al., 1987, but is readily distinguished from the former genus by the distinctly divided esophagus and the absence of cervical flanges and lateral alae, and from the latter genus by the postesophageal position of the excretory pore and cervical papillae and the presence of preanal unpaired papilla in males. Close morphological similarities between Wakubitinema and Paraquimperia may suggest that Wakubitinema has evolved from a quimperiid fish.

Animals↗
PubMed1988

Patterns of correspondence between skin rings and vertebrae in gymnophiona (Amphibia).

The skin annulation seems to have a direct relation with the vertebral column segmentation. The type of rings, primary, secondary, tertiary, or quaternary set by binary division, probably results in an induction process during morphogenesis. The diverse stages of this division appear and are rubbed out from front to rear. The topographical correspondence is different for 3 distinct parts of the body: the collar, the trunk, and the posterior part. In this last region, we can find a more or less reduced true tail or a terminal appendage without vertebral element. All these new morphological data support elements of functional indications.

Amphibians↗
PubMed1988

The chromaffin cells of Siren lacertina (Amphibia, Urodela): cytological characteristics and evidence of exocytosis.

In the adrenal gland of Siren lacertina three types of chromaffin cells are described, on the basis of size, shape and electron density of the cytoplasmic granules: adrenaline-secreting cells, noradrenaline-secreting cells and small granulated chromaffin-cells. In A-cells exocytotic profiles are described, in which the granule membrane fuses with the plasma membrane and the granule core is discharged into the intercellular space.

Adrenal Glands↗