Disconnected optic axons persist in the visual pathway during regeneration of the retino-tectal projection in the frog (original) (raw)
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Restoration of retino-tectal connections in frogs during regeneration of the optic nerve
Neurophysiology
At various times after unilateral division of the optic nerve in the frogRana temporaria L. evoked potentials in response to electrical stimulation of the optic nerve were investigated in a segment distal to the site of operation, spike activity was recorded from endings of regenerating and intertectal axons when stimuli of different shapes were placed in the field of vision, and the distribution of axonal bulbs of growth by depth in the tectum mesencephal was studied electron-microscopically. During regeneration of the axons the responses of the retinal ganglionic cells to visual stimuli retained most of their individual features. Myelinated axons of the retinal ganglionic cells regenerate first (starting on the 21st day after operation). Myelination of these fibers lags significantly behind their growth and is complete more than 100 days after the operation. Unmyelinated axons of the retinal ganglionic cells grow up toward the tectum mesencephali after myelinated axons (80 or more...
The Journal of Comparative Neurology, 1983
The mode of entry of retinal ganglion cell (RGC) axons and the detailed morphology of their arbors has been studied in the tectal lobes of the frog Rana pipiens. These tecta were subjected intact to H R P histochemistry and subsequently flat-mounted for examination under a compound microscope. Subsets of RGC axons were labelled by inserting small pellets of solidified HRP into the optic chiasm region or into the tectal neuropil itself. Annular or semiannular patterns of retinal ganglion cell arbors were always observed after placement of HRP in the chiasm region. HRP pellets in the tectal neuropil labelled segments of annuli in caudal tectal regions. These tectal patterns corresponded to a similar annular distribution of HRP-filled RGC bodies in the topographically appropriate regions of the contralateral retina.
The Journal of Neuroscience, 1985
Labeled proteins in intact and regenerating optic nerves of juvenile Xenopus clawed frogs were examined at three different time points (2 to 4 hr, 18 hr, and 5 to 9 days) following [35S]methionine injection into the eye. The distal axon tips of optic nerves were transected at the margin of the tectal lobe and regeneration of the nerve was followed by three methods: autoradiography, tissue section counting following [3H]proline injection into the eye, and electrophysiological mapping of the visual field projection. By these methods, regrowth was found to occur 2 weeks after transection, but the fibers had not yet sorted their retinotopic pattern. Two-dimensional gel separation of labeled nerve proteins revealed 250 to 300 identifiable proteins, 89 of which (including all spots which differed consistently upon direct comparison of regenerating versus normal nerves) were selected for quantitative treatment. Nine of these spots (240, 135, 65, 64, 58, 54, 56, 31, and 26 kilodaltons) were...
Displaced retinal ganglion cells in normal frogs and those with regenerated optic nerves
Anatomy and Embryology, 1992
We have analysed the number and spatial distribution of displaced retinal ganglion cells in the frog Litoria (Hyla) moorei. A series of normal animals was compared with one in which the optic nerve was crushed and allowed to regenerate. Ganglion cells were labelled with horseradish peroxidase (HRP) applied to the optic nerve, and retinae were examined as sections or whole mounts. We analysed separately ganglion cells with somata displaced to the inner nuclear (Dogiel cells, DGCs) and to the inner plexiform layer (IPLGCs). These findings were related to data for the orthotopic ganglion cells (OGCs). The mean number of DGCs in the normal series was 2,550 (• 281) and fell to 1,630 (_+ 321) after regeneration, representing a mean loss of 36%. This reduction was not significantly different from the mean loss of 43% from the OGC population in which mean values fell from 474,700 (+47,136) to 268,700 (-t-54,395). In both the normal and the regenerate series, DGCs were estimated to represent means of only 0.6% of the OGC population. Densities of DGCs were highest in the nasoventral and temporo-dorsal peripheries; densities of both DGCs and OGCs were lower after optic nerve regeneration. We conclude that the factors which affect ganglion cell death during optic nerve regeneration, do so to similar extents amongst the DGC and the OGC populations. The IPLGCs were very rare in normal animals with a mean of 420 (_+ 95). However, their numbers increased after regeneration to a mean of 3,350 (_+ 690), estimated to be 1.2% of the OGC population. These cells normally favoured peripheral retina but became pan-retinal after regeneration. The primary dendrites of the majority of IPLGCs were oriented in the same direction as those of OGCs. We conclude that most IPLGCs were OGCs which had relocated their somata to the inner plexiform layer.
Journal of Neurocytology, 1988
This study examines the cell body response to axotomy of retinal ganglion cells in the frog Rana pipiens. Cell soma sizes were measured in carefully matched regions of Nissl-stained wholemounted retinae after either nerve crush, nerve cut with stump separation, nerve crush with intraocular nerve growth factor (NGF) or nerve cut with NGF applied to the proximal stump. The state of axonal regeneration was also assessed in each case by anterograde transport of HRP.
Development, 1987
The optic tract of the goldfish splits into two brachia just before it reaches the tectum, normal optic axons being distributed systematically between the two according to their retinal origins. The orderliness of this division, like that of the retinotectal projection itself, is conventionally attributed to a system of specific axonal guidance cues. However, the brachial distribution of regenerated axons is much less orderly; and, since there is evidence that these axons have many collateral branches in the nerve and tract, the gross order that remains after regeneration could potentially arise secondarily, in parallel with refinement of the retinotectal map, by a preferential loss of collaterals from the inappropriate brachium. The brachial paths of normal axons, and axons regenerated after optic nerve cut for periods ranging from 19 days to 5 years, were therefore studied by anterograde labelling with horseradish peroxidase from discrete retinal lesions or retrograde labelling of...
Tectal pathways of regenerating goldfish optic axons after nasal or temporal half retinal removal
1988
The tectal pathways of regenerating goldfish optic axons are abnormal but not random. The relative proportion of temporal axons is highest in rostral tectum (65 %) drops in midtectum (31 %) and is very low in caudal tectum (4 %). By contrast, nasal axons proceed into caudal tectum and are therefore relatively evenly distributed throughout the tectum. In this study, we have tested whether temporal axons are confined to rostral tectum by the presence of nasal axons in caudal tectum or whether they have a preference for rostral tectum regardless of other axons. We similarly tested whether nasal axons would grow preferentially into caudal tectum in the absence of temporal axons.
Loss and displacement of ganglion cells after optic nerve regeneration in adultRana pipiens
Brain Research, 1985
Key words: regeneration --Rana pipiens --optic nerve --retinal cell death --cell displacement --displaced amacrine cell After studying pathway selection in the brain of Rana pipiens during unilateral optic nerve regeneration, several frogs were allowed to survive for lengthy periods for use in the present investigation. Retina flat-mounts were prepared from both eyes at 42-50 weeks postoperation. In some cases, HRP was infiltrated into both optic nerves prior to sacrifice to assist in identifying retinal ganglion cells. All specimens showed reduced cell-densities in the ganglion cell layer of the eye that had sustained the nerve regeneration. In addition, many ganglion cells were displaced, abnormally, into the inner plexiform layer, and the normally-situated cells formed irregular bands and islands in some parts of the retina. Cell-counts showed an apparently time-related change in neuron number ranging from a loss of 41% compared with the unaffected eye at 42 weeks, to losses as great as 71% at 50 weeks. The probable number of displaced amacrine cells in the ganglion cell layer, assumed to be unaffected by the experiment, was estimated at a maximum of 16%. Possible factors underlying the loss and displacement of ganglion cells are discussed.
Effect of different optic nerve lesions on retinal ganglion cell death in the frog Rana pipiens
Journal of Comparative Neurology, 1987
Following optic nerve crush in various species of frog, a proportion of the retinal ganglion cells re‐establishes functional contact with the optic tectum. However, as much as 50% of the retinal ganglion cells die during this process. The determinants of an individual ganglion cell's fate have not been established. In this study of Rana pipiens, cell survival after optic nerve crush was compared with that after nerve cut followed by stump separation, a procedure that considerably delayed entry of optic axons to the brain. It was also ascertained, in the case of delayed ingrowth, whether application of nerve growth factor immediately after lesion influenced the cell death process.This study confirmed that retinal ganglion cell death is a relatively late event in regeneration, because in several animals‐where anterograde HRP labeling demonstrated regenerating axons within the tectum, no cell death had occurred. There was no statistically significant difference in cell death at 75 ...