The growth of the retina in Xenopus laevis: an autoradiographic study

Development ◽  
1971 ◽  
Vol 26 (1) ◽  
pp. 67-79
Author(s):  
K. Straznicky ◽  
R. M. Gaze
Keyword(s):  
Xenopus Laevis ◽  
Ganglion Cells ◽  
Tritiated Thymidine ◽  
Autoradiographic Study ◽  
Ciliary Margin

The growth of the retina has been studied in Xenopus by use of autoradiography with tritiated thymidine. At the time when retinal polarization first occurs (around stage 30) there are only some 20 ganglion cells across the retinal equator and the rest of the retina develops later, by annular addition of cells at the ciliary margin. This process continues beyond metamorphosis.

The development of the tectum in Xenopus laevis: an autoradiographic study

Development ◽  
1972 ◽  
Vol 28 (1) ◽  
pp. 87-115
Author(s):  
K. Straznicky ◽  
R. M. Gaze
Keyword(s):  
Xenopus Laevis ◽  
Dna Synthesis ◽  
Optic Tectum ◽  
Tritiated Thymidine ◽  
Dorsal Surface ◽  
Autoradiographic Study ◽  
Cell Type ◽  
Pole Cells ◽  
Serial Addition ◽  
The Times

The development of the optic tectum in Xenopus laevis has been studied by the use of autoradiography with tritiated thymidine. The first part of the adult tectum to form is the rostroventral pole; cells in this position undergo their final DNA synthesis between stages 35 and 45 or shortly thereafter. Next, the cells comprising the ventrolateral border of the tectum form. These cells undergo their final DNA synthesis at or shortly after stage 45. Finally the cells comprising the dorsal surface of the adult tectum form, mainly between stages 50–55. This part of the tectum originates from the serial addition of strips of cells medially, which displace the pre-existing tissue laterally and rostrally. The formation of the tectum is virtually complete by stage 58. The tectum in Xenopus thus forms in topographical order from rostroventral to caudo-medial. The distribution of labelled cells, several stages after the time of injection of isotope, indicates that, at any one time, a segment of tectum is forming which runs normal to the tectal surface and includes all layers from the ventricular layer out to the surface. In Xenopus, therefore, the times of origin of tectal cells appear to be related not to cell type or tectal layer but to the topographical position of the cells across the surface of the tectum.

The growth of the retina in Xenopus laevis, an autoradiographic study

Development ◽  
1972 ◽  
Vol 27 (2) ◽  
pp. 381-387
Author(s):  
Joan D. Feldman ◽  
R. M. Gaze
Keyword(s):  
Cell Division ◽  
Xenopus Laevis ◽  
Compound Eye ◽  
Normal Animal ◽  
Autoradiographic Study ◽  
Compound Eyes ◽  
Dorsoventral Axis ◽  
Experimental Animals ◽  
Cut Edge ◽  
Ciliary Margin

The retina of Xenopus laevis has previously been shown, using autoradiographic methods, to develop in the normal animal by the annular addition of cells at the ciliary margin. The development of the retina in animals with surgically produced “compound eyes” was subsequently studied. In these animals the eye cup was split along the dorsoventral axis and the resulting half-eyes were recombined so as to form animals with a double-nasal eye. The retina in experimental animals was found to develop as in the normal animal. No labelling of cells with radioactive thymidine was seen along the cut edge of each half-eye; thus in terms of cell division each half of the compound eye remains a half.

Specification of retinotectal connexions during development of the toad Xenopus laevis

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 77-92
Author(s):  
S. C. Sharma ◽  
J. G. Hollyfield
Keyword(s):  
Xenopus Laevis ◽  
Ganglion Cell ◽  
Retinal Ganglion Cells ◽  
Optic Tectum ◽  
Ganglion Cells ◽  
The Other ◽  
Retinal Ganglion ◽  
Visual Projection ◽  
Series Of Experiments ◽  
The Right

The specification of central connexions of retinal ganglion cells was studied in Xenopus laevis. In one series of experiments, the right eye primordium was rotated 180° at embryonic stages 24–32. In the other series, the left eye was transplanted into the right orbit, and vice versa, with either 0° or 180° rotation. After metamorphosis the visual projections from the operated eye to the contralateral optic tectum were mapped electrophysiologically and compared with the normal retinotectal map. In all cases the visual projection map was rotated through the same angle as was indicated by the position of the choroidal fissure. The left eye exchanged into the right orbit retained its original axes and projected to the contralateral tectum. These results suggest that retinal ganglion cell connexions are specified before stage 24.

Postnatal neurogenesis in the olfactory bulbs of a lizard. A tritiated thymidine autoradiographic study

1989 ◽  
Vol 98 (3) ◽  
pp. 247-252 ◽  
Author(s):  
J.M. Garcia-Verdugo ◽  
S. Llahi ◽  
I. Ferrer ◽  
C. Lopez-Garcia
Keyword(s):  
Tritiated Thymidine ◽  
Autoradiographic Study ◽  
Postnatal Neurogenesis ◽  
Olfactory Bulbs

Studies on the Autonomy of Pellicular DNA in Paramecium

1969 ◽  
Vol 5 (2) ◽  
pp. 365-372
Author(s):  
JOAN SMITH-SONNEBORN ◽  
W. PLAUT
Keyword(s):  
Dna Synthesis ◽  
Tritiated Thymidine ◽  
Autoradiographic Study ◽  
Sensitive Material ◽  
Selective Labelling ◽  
The Relationship

This autoradiographic study was designed to elucidate the relationship between the macronucleus and pellicular DNA in Paramecium. The capacity of the cell to synthesize pellicular DNA in the absence of the macronucleus was established by demonstrating the incorporation of tritiated thymidine into DNase-sensitive material in the pellicles of amacronucleate cells. Moreover, using a technique which leads to selective labelling of the macronucleus in normal paramecia, we have looked for evidence of transfer of labelled DNA from the macronucleus to the pellicle with time. Finding none, we conclude that labelled pellicular DNA is not of macronuclear origin, and that labelled pellicular DNA synthesis is not directly dependent on the presence of the macronucleus.

Retinal growth in double dorsal and double ventral eyes in Xenopus

Development ◽  
1977 ◽  
Vol 40 (1) ◽  
pp. 175-185
Author(s):  
K. Straznicky ◽  
D. Tay
Keyword(s):  
Xenopus Laevis ◽  
Compound Eye ◽  
Ganglion Cells ◽  
Cell Number ◽  
Early Embryogenesis ◽  
Time Points ◽  
Retinal Growth

The growth of normal and surgically produced compound dorsal and ventral retinae in Xenopus laevis has been studied autoradiographically following injections of [3H]thymidine at stages 50 and 58. The animals were sacrificed 3 weeks after metamorphosis. The histogenetic pattern of the dorsal and ventral retinal halves was different at the three time points investigated, i.e. up to stage 50, between stages 50 and 58 and between stage 58 and 3 weeks after metamorphosis. Asymmetrical dorsal retinal growth occurred up to stage 50. From stage 50 onwards the retinal growth tendency reversed so that more ganglion cells were produced along the ventral than the dorsal ciliary margins. The overall preponderance of ventral retinal growth was 32·4% in cell number and 12·4% in retinal length from early embryogenesis to 3 weeks after metamorphosis. The characteristic histogenetic pattern of the dorsal and ventral retinal halves was maintained in an ectopic position in the compound eye, indicating that this particular property of the retinal halves is intrinsically determined.

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.

scholarly journals Tritiated thymidine autoradiographic study on origin and renewal of gastrin cells in antral area of hamsters

1980 ◽  
Vol 79 (5) ◽  
pp. 785-791 ◽  
Author(s):  
Sotaro Fujimoto ◽  
Takanori Hattori ◽  
Kunihiko Kimoto ◽  
Shigeo Yamashita ◽  
Setsuya Fujita ◽  
...  
Keyword(s):  
Tritiated Thymidine ◽  
Autoradiographic Study ◽  
Gastrin Cells ◽  
Antral Area
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