scholarly journals Experimental Analysis of the Eye Morphogenesis in Mammals

Development ◽  
1960 ◽  
Vol 8 (3) ◽  
pp. 349-368
Author(s):  
O. G. Stroeva

Owing to the great difficulties of experimental interference with the embryogenesis of mammals, the morphogenetic potentialities of the mammalian eye remain almost unstudied up to the present. The elucidation of whether the developing mammalian eye obeys the same rules that have been established for the lower vertebrates, or whether its development proceeds in another way, is interesting in many respects. It might allow us to answer a number of questions, e.g. how stable are the morphogenetic interactions within the vertebrates which result in the formation of homologous organs? How do the morphogenetic potentials of the parts of an organ alter in the course of evolution? Light might also be thrown on the development or loss of regenerative capacity in various forms. Lastly, we may find out to what extent the experiments on lower vertebrates, easily carried out on a large scale, are of use for the understanding of those processes which cause regularly recurring inborn malformations in man.

Development ◽  
1968 ◽  
Vol 20 (1) ◽  
pp. 129-140
Author(s):  
A. A. Neyfakh ◽  
N. N. Rott

For studying nucleo-cytoplasmic relations during development various selective influences on the nucleus and cytoplasm are widely used as the main method of experimental analysis. However, the application of such techniques presents difficulties both in obtaining evidence that shows the specificity of a nuclear or cytoplasmic effect by a chosen agent and in the quantitative evaluation of the extent of damage. In this paper a method is described for differentiating between nuclear and cytoplasmic sites of action of a given agent as well as for evaluating quantitatively the extent of nuclear damage. The method is based on the determination of the morphogenetic activity of nuclei at different stages of embryonic development. As has been previously shown, after complete inactivation of nuclei (for instance, by heavy doses of radiation) development proceeds up to the stages programmed for by the genetic cell apparatus (Neyfakh, 1959, 1964).


2014 ◽  
Vol 9 (0) ◽  
pp. 3405063-3405063 ◽  
Author(s):  
Hidetoshi KUDOH ◽  
Tsuyoshi YAGAI ◽  
Kei HAMANO ◽  
Kazuki YOSHIDA ◽  
Shinji HAMAGUCHI ◽  
...  

2014 ◽  
Vol 472 ◽  
pp. 27-30
Author(s):  
Yong Jiang

The working process of the out-moving jaw crusher is complex vibration system with multeity freedoms, it is vibration Characteristics directly affect the performance of the machine. The thesis put PWD120150 as research target, experimental analysis was conduct to the typical vibration Characteristics, the natural frequency and the working frequency of the machine and key components was obtained, which provided references for the design of avoiding mechanical resonance, and provided technical reference to the vibration analysis of the large scale equipment.


2015 ◽  
Vol 62 (3-4) ◽  
pp. 77-99 ◽  
Author(s):  
Donatella Termini

AbstractLaboratory experiments in a straight flume were carried out to examine the evolution of large-scale horizontal turbulent structures under flat-bed and deformed-bed conditions. In this paper, the horizontal turbulence of flow under these conditions is analyzed and compared. The conditioned quadrant method is applied to verify the occurrence of turbulent events. The distributions of horizontal Reynolds shear stress and turbulent kinetic energy are also presented and discussed. Results show the occurrence of an “initial” sequence of horizontal vortices whose average spatial length scales with the channel width. Under deformed-bed conditions, this spatial length does not change.


Biomolecules ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1204 ◽  
Author(s):  
Lousanne de Wit ◽  
Juntao Fang ◽  
Klaus Neef ◽  
Junjie Xiao ◽  
Pieter A. Doevendans ◽  
...  

Cardiovascular disease is the leading cause of death worldwide. Current palliative treatments can slow the progression of heart failure, but ultimately, the only curative treatment for end-stage heart failure is heart transplantation, which is only available for a minority of patients due to lack of donors’ hearts. Explorative research has shown the replacement of the damaged and lost myocardium by inducing cardiac regeneration from preexisting myocardial cells. Lower vertebrates, such as the newt and zebrafish, can regenerate lost myocardium through cardiomyocyte proliferation. The preexisting adult cardiomyocytes replace the lost cells through subsequent dedifferentiation, proliferation, migration, and re-differentiation. Similarly, neonatal mice show complete cardiac regeneration post-injury; however, this regenerative capacity is remarkably diminished one week after birth. In contrast, the adult mammalian heart presents a fibrotic rather than a regenerative response and only shows signs of partial pathological cardiomyocyte dedifferentiation after injury. In this review, we explore the cellular and molecular responses to myocardial insults in different adult species to give insights for future interventional directions by which one can promote or activate cardiac regeneration in mammals.


Development ◽  
1962 ◽  
Vol 10 (2) ◽  
pp. 115-126
Author(s):  
R. T. Sims

The literature on regeneration in the central nervous system of vertebrates has been reviewed exhaustively by Windle (1955, 1956). Adult fish and urodeles reestablish physiological and anatomical continuity of the spinal cord after it has been completely transected while adult anurans (Piatt & Piatt, 1958) and mammals on the whole do not. In all groups of vertebrates regeneration is more successful in the period of early embryonic development, and becomes less so as development proceeds. Experiments designed to investigate the factors responsible for this change demand an animal in which the difference in the regenerative capacity of embryonic and adult form is marked, and all stages of development are easily accessible for operative procedures. These criteria are satisfied by Anura. For this reason regeneration in the anuran central nervous system merits further investigation. After spinal cord transection in urodele larvae, Piatt (1955) found that the Mauthner axons did not regenerate although other axons around them did.


Evidence is presented to support the conclusion that normally functioning optic nerve fibre terminal arborizations are open to continuous modification of their location and that they are capable of large scale gradual movement across the optic tectum in lower vertebrates. The termination of optic fibres at precisely defined tectal locations during normal embryonic development does not appear, in view of this and other evidence, to be due to any restrictions imposed by specializations distinguishing terminal sites themselves. However, there is clear evidence that, on the basis of possibly very simple specializations acquired as part of their embryological origin at particular locations in the retina, growing optic fibres actively and continuously select specific routes to be followed through intervening nervous tissue which eventually lead them to predictable and at least approximately appropriate terminal regions in the tectum. It is proposed that terminals move into and maintain fully retinotopic order as a result of direct interactions between fibres themselves based on features correlated with the retinal proximity of their cells of origin. This may involve further use of specializations due to related embryological origin: correlations in nerve impulse activity among neighbouring retinal ganglion cells may serve to stabilize most favourable terminal combinations. It is argued that fibres are subject to multiple influences which contribute to their orderly growth and that the demands made on the embryological differentiation of nervous tissue can thereby be considerably reduced.


JOM ◽  
2021 ◽  
Author(s):  
Arne Simons ◽  
Inge Bellemans ◽  
Tijl Crivits ◽  
Kim Verbeken

2013 ◽  
Vol 278-280 ◽  
pp. 771-776
Author(s):  
Chun Xia Chen ◽  
Yu Ming Zhang ◽  
Yong Hua Yang

Based on environmental stochastic excitation, a large scale modal test was conducted at an important section of Shanghai Metro Line 1. According to the collected time response data, the natural frequencies of the soft soil-tunnel system were obtained by means of theoretical and experimental analysis, which can provide calculation parameters for further relevant dynamic analysis.


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