The induction of an anomalous ipsilateral retinotectal projection in Xenopus laevis

1990 ◽  
Vol 181 (4) ◽  
Author(s):  
J.S.H. Taylor ◽  
R.M. Gaze
Keyword(s):  
Xenopus Laevis ◽  
Retinotectal Projection

Visual deprivation and the maturation of the retinotectal projection in Xenopus laevis

Development ◽  
1986 ◽  
Vol 91 (1) ◽  
pp. 101-115
Author(s):  
M. J. Keating ◽  
S. Grant ◽  
E. A. Dawes ◽  
K. Nanchahal
Keyword(s):  
Xenopus Laevis ◽  
Neural Activity ◽  
Ganglion Cells ◽  
Chronic Administration ◽  
Visual Deprivation ◽  
Lower Vertebrate ◽  
Initial Development ◽  
Retinotectal Projection ◽  
Spontaneous Neural Activity ◽  
Retinotectal System

There has been a resurgence of interest, recently, in the possible role of neural activity in the ordering of synaptic connections in the lower vertebrate retinotectal system. Blockade of all neural activity, by chronic administration of tetrodotoxin (TTX), during the regeneration of the optic nerve in goldfish has been found to prevent the re-emergence of a fully ordered retinotectal projection. We sought to determine the effects of visual deprivation, a less radical perturbation of neural activity than that produced by TTX, on the initial development of the retinotectal projection. The contralateral visuotectal projection was studied in Xenopus laevis which had been reared in darkness from before the onset of visual function. The projection mapped electrophysiologically at metamorphic climax, or in postmetamorphic juveniles, showed a normal retinotopic topography. The topographic precision of the projection, as revealed by the multiunit receptive field sizes, was the same in light- and dark-reared animals. The laminar distribution, in the superficial neuropil of the optic tectum, of terminals from different classes of retinal ganglion cells was also normal. It is concluded that the specific retinotectal connections underlying these features of the projection are generated by intrinsic developmental processes which do not require visual experience. Among these intrinsic processes might be ‘spontaneous’ neural activity.

The retinotectal projection from a double-ventral compound eye in Xenopus laevis

Development ◽  
1974 ◽  
Vol 31 (1) ◽  
pp. 123-137
Author(s):  
K. Straznicky ◽  
R. M. Gaze ◽  
M. J. Keating
Keyword(s):  
Xenopus Laevis ◽  
Compound Eye ◽  
Retinotectal Projection ◽  
Temporal Direction

The retinotectal projection was mapped in 22 post-metamorphic Xenopus in which the eye under investigation had been made double-ventral by operation at stage 32. The contralateral retinotectal projection from a double-ventral eye is neither normal nor does it show the type of abnormality predicted from previous work on double-nasal and double-temporal eyes. In the case of double-ventral eyes, the nasal part of the field projection tended to be reduplicated about the horizontal midline and those field positions corresponding to lateromedial rows of electrode positions on the tectum ran ventrodorsally in the field. As the electrode rows on the tectum progressed more caudally, so the corresponding rows of stimulus positions in the field tended to curl in a temporal direction. These observations have been interpreted as indicating that the nasotemporal and dorsoventral polarities of the eye are not irreversibly determined at stage 32 and that the mechanisms generating the nasotemporal and dorsoventral axes of the eye may interact with each other.

The retinotectal projection of quarter eyes in Xenopus laevis

1986 ◽  
Vol 29 (1) ◽  
pp. 141-143 ◽  
Author(s):  
Norbert Degen ◽  
Kurt Brändle
Keyword(s):  
Xenopus Laevis ◽  
Retinotectal Projection

Androgen-induced plasticity at a “vocal” neuromuscular synapse

1994 ◽  
Vol 52 ◽  
pp. 32-33
Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman
Keyword(s):  
Xenopus Laevis ◽  
Motor Neurons ◽  
Sexual Differentiation ◽  
Molecular Basis ◽  
Neuromuscular Synapse ◽  
Sexually Dimorphic ◽  
Intracellular Protein ◽  
Developmental Program ◽  
Androgen Action ◽  
Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

THE EFFECT OF THE SKIN SECRETION OF XENOPUS LAEVIS ON ITS DERMAL MELANOPHORES

1956 ◽  
Vol 23 (3) ◽  
pp. 265-273 ◽  
Author(s):  
A. C. J. Burgers ◽  
G. J. van Oordt
Keyword(s):  
Xenopus Laevis ◽  
Skin Secretion
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