A Physiological Interpretation of the Mechanism Involved in the Determination of Bilateral Symmetry in Amphibian embryos

Development ◽  
1958 ◽  
Vol 6 (1) ◽  
pp. 15-27
Author(s):  
Søren Løvtrup
Keyword(s):  
Density Gradient ◽  
Bilateral Symmetry ◽  
Amphibian Embryos ◽  
Present Context

Very great interest has been taken in the question of the nature of those factors which determine the bilateral symmetry in amphibian embryos. Numerous experimental observations have been published, and various hypotheses and theories have been advanced to account for the results. The problem has been thoroughly discussed in several reviews (of which many of the more recent will be quoted below) and it would for this reason alone be out of place to review the literature in the present context. For orientation, the present views upon the problem will be presented in brief outline. It seems that factors responsible for bilateral symmetry are located partly in the fluid cytoplasm in the interior of the egg, and partly in the more solid cortex. It has previously been thought that the organization of the cytoplasm was determined by the influence of gravity, the constituents being distributed simply according to a density gradient.

Inversion of the Dorso-ventral Axis in Amphibian Embryos by Unilateral Restriction of Oxygen Supply

Development ◽  
1958 ◽  
Vol 6 (3) ◽  
pp. 486-490
Author(s):  
S. Løvtrup ◽  
A. Pigon
Keyword(s):  
Oxygen Supply ◽  
Nile Blue ◽  
Bilateral Symmetry ◽  
Radial Symmetry ◽  
Point Of View ◽  
Low Permeability ◽  
Grey Crescent ◽  
Protein Coat ◽  
Amphibian Embryos

According to the hypothesis advanced by Løvtrup (1958) the supply of oxygen is one of the factors responsible for the determination of bilateral symmetry in amphibian embryos. The protein coat covering the outside of the egg is known to have a very low permeability (Holtfreter, 1943), and it was suggested in the hypothesis that the formation of the grey crescent consists in a stretching of this coat by which the permeability is increased (cf. the work of Dalcq & Dollander (1948) and of Dollander & Melnotte (1952) on permeability of Nile blue), in this way the radial symmetry of the egg is changed to a bilateral symmetry from a metabolic point of view. As a consequence of the increase in permeability those oxidative, energy-supplying processes which are associated with gastrulation are enabled to proceed at a higher rate at one side of the egg.

scholarly journals FITNESS AND COMFORT ASSESSMENT OF FOOTWEAR: AN ANTHROPOMETRIC APPRAISAL

2021 ◽  
Vol 28 (3) ◽  
pp. 80-86
Author(s):  
Adinife Patrick Azodo ◽  
◽  
Olasunkanmi Salami Isamaila ◽  
Sampson Chisa Owhor ◽  
◽  
...  
Keyword(s):  
Design Pattern ◽  
Female Gender ◽  
Bilateral Symmetry ◽  
Anthropometric Parameters ◽  
Data Utilization ◽  
Anthropometric Parameter ◽  
Paired Samples ◽  
Effective Use ◽  
Footwear Design

Suitability determination of any product designed for specific types of consumers is possible through the effective use of anthropometric information. This study assessed anthropometric data utilization in footwear designs and patterns as an indicator of fitness and comfort in footwear production. The data collected for analysis were the length and the breadth dimensions of footwear design pattern from eighteen footwear cottage shops and the foot anthropometric parameter from a total of four hundred and thirty-three (433) (males (226) and females (207)) subjects. The instrumentation design for the data collection was a digital vernier caliper (model Mitutoyo 500-506-10). The analysis of the foot anthropometry dimension and the design footwear pattern data obtained showed a lack of bilateral symmetry for the male and female gender. The fitness and comfortable foot support function of the footwear analyzed using a paired samples t-test between the footwear design pattern dimensions, and the foot anthropometric parameters disclosed p > 0.05 in all cases – not significant. This study concluded that tailoring a product design to the users’ population reduces the mismatch challenges, grants fitness, and comfort to the users.

Cytotoxicity of Subpopulations of Splenic Cells from Normal and Fibrosarcoma - Bearing Mice towards Syngeneic Tumour Cells

1983 ◽  
Vol 69 (6) ◽  
pp. 489-496 ◽  
Author(s):  
Vimal Suhas Aroskar ◽  
Chintamani Shankar Godbole ◽  
Kamlakar Anant Chaubal
Keyword(s):  
Density Gradient ◽  
Cell Populations ◽  
Tumour Bearing ◽  
Splenic Cell ◽  
Cytotoxicity Studies ◽  
Tumour Bearing Mouse ◽  
Splenic Cells ◽  
Step Density ◽  
Group Density

The nonadherent splenic cells from normal and tumour-bearing (mouse fibrosarcoma-MFS) Swiss mice were divided into 6 subpopulations on Percoll step density gradient and characterised. For the determination of their cytotoxicity towards syngeneic MFS cells and their electrophoretic mobility (EPM), the splenic cell populations were pooled to form 2 broad groups: a lower-density group (density of saline to just < 1.069 g/ml) and a higher-density group (1.069 to just < 1.087 gm/ml). In general, the splenic cells from mice bearing 10- to 11-day-old MFS tumours differed in certain characteristics from those of normal mice in that they showed an increase in the following: proliferation, heterogeneity, with appearance of large cells (>70 μ2); cells with a lower density (< 1.069 g/ml); cells with a lower (< 0.85 μ/sec/Volt/cm) anodi cEPM. The cytotoxicity studies revealed that: a) the lower-density splenic cells of both normal and tumour-bearing mice were more cytotoxic than the higher-density splenic cells; b) the lower- and higher-density splenic cells of tumour-bearing mice were more cytotoxic than the corresponding cells of normal mice. These findings indicate that the splenic cells of mice with a lower EPM and a lower density are the main contributors of cell-mediated cytolysis of a subpopulation of MFS cells.

On the Regulation of Bilateral Symmetry in Plutei with Exchanged Meridional Halves and in Giant Plutei

Development ◽  
1957 ◽  
Vol 5 (1) ◽  
pp. 60-73
Author(s):  
Sven Hörstadius
Keyword(s):  
Sea Urchin ◽  
Frontal Plane ◽  
Vital Staining ◽  
Bilateral Symmetry ◽  
Sea Urchin Egg ◽  
The Subject ◽  
The Moment ◽  
Late Stages

The determination of bilateral symmetry in the sea-urchin egg has been the subject of investigations which have yielded contradictory results. The earlier literature was reviewed in 1936 (Hörstadius & Wolsky). It may therefore suffice to mention only the following points in this paper. The problem of whether or not the sperm induces the bilateral symmetry in the sea-urchin egg has not been solved by direct experimentation. By means of local vital staining opposite the point of sperm entrance Hörstadius (1928) concluded that there was no relation between the entrance point of the sperm and the position of the first furrow. The stain applied at the moment of fertilization soon became so diffuse that it was impossible to recognize the point of staining in late stages. It was at that time considered that the first furrow generally cut through the egg in either the median or the frontal plane, and only comparatively seldom obliquely to these planes (von Ubisch, 1925; Runnström, 1925; Hörstadius, 1928).

Numerical determination of the singularity order of a system of differential equations

2020 ◽  
Vol 28 (1) ◽  
pp. 17-34
Author(s):  
Ali Baddour ◽  
Mikhail D. Malykh ◽  
Alexander A. Panin ◽  
Leonid A. Sevastianov
Keyword(s):  
Differential Equations ◽  
Integrable Hamiltonian System ◽  
Computer Experiments ◽  
Completely Integrable Hamiltonian System ◽  
Painlevé Property ◽  
Branching Points ◽  
Present Context ◽  
Singularity Order ◽  
Complex Scheme

We consider moving singular points of systems of ordinary differential equations. A review of Painlevé’s results on the algebraicity of these points and their relation to the Marchuk problem of determining the position and order of moving singularities by means of finite difference method is carried out. We present an implementation of a numerical method for solving this problem, proposed by N. N. Kalitkin and A. Al’shina (2005) based on the Rosenbrock complex scheme in the Sage computer algebra system, the package CROS for Sage. The main functions of this package are described and numerical examples of usage are presented for each of them. To verify the method, computer experiments are executed (1) with equations possessing the Painlevé property, for which the orders are expected to be integer; (2) dynamic Calogero system. This system, well-known as a nontrivial example of a completely integrable Hamiltonian system, in the present context is interesting due to the fact that coordinates and momenta are algebraic functions of time, and the orders of moving branching points can be calculated explicitly. Numerical experiments revealed that the applicability conditions of the method require additional stipulations related to the elimination of superconvergence points.

Numerical determination of the singularity order of a system of differential equations

2020 ◽  
Vol 28 (1) ◽  
pp. 17-34
Author(s):  
Ali Baddour ◽  
Mikhail D. Malykh ◽  
Alexander A. Panin ◽  
Leonid A. Sevastianov
Keyword(s):  
Differential Equations ◽  
Integrable Hamiltonian System ◽  
Computer Experiments ◽  
Completely Integrable Hamiltonian System ◽  
Painlevé Property ◽  
Branching Points ◽  
Present Context ◽  
Singularity Order ◽  
Complex Scheme

We consider moving singular points of systems of ordinary differential equations. A review of Painlevé’s results on the algebraicity of these points and their relation to the Marchuk problem of determining the position and order of moving singularities by means of finite difference method is carried out. We present an implementation of a numerical method for solving this problem, proposed by N. N. Kalitkin and A. Al’shina (2005) based on the Rosenbrock complex scheme in the Sage computer algebra system, the package CROS for Sage. The main functions of this package are described and numerical examples of usage are presented for each of them. To verify the method, computer experiments are executed (1) with equations possessing the Painlevé property, for which the orders are expected to be integer; (2) dynamic Calogero system. This system, well-known as a nontrivial example of a completely integrable Hamiltonian system, in the present context is interesting due to the fact that coordinates and momenta are algebraic functions of time, and the orders of moving branching points can be calculated explicitly. Numerical experiments revealed that the applicability conditions of the method require additional stipulations related to the elimination of superconvergence points.

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