The development of the optic lobes in Xenopus laevis. The effect of repeated crushing of the optic nerve

McMurray, Virginia M.

doi:10.1002/jez.1401250205

Cited by 22 publications

(1 citation statement)

References 21 publications

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“…The hypoplasia after removal of sense organs in amphibia may also be due to direct effects on the maintenance of neurones, as suggested above. In one case, however, effects on proliferation of nerve cells in the brain can account for the resulting hypoplasia: in anurans reduction of mitotic activity accounts for the differences in the cell number between the two sides of the optic lobe in the hypoplasia resulting from unilateral embryonic eye enucleation or after repeated crushing and regeneration of the optic nerve (Kollross, 1953; McMurray, 1954).…”

Section: Reactions Of the Nervous System To Peripheral Changes In mentioning

confidence: 99%

The Experimental Embryology of the Foetal Nervous System

Hess

1957

Biological Reviews

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SUMMARY It is feasible to submit the mammalian foetus to surgery and the types of operation thus far performed are reviewed. Other techniques for affecting mammalian organs during development, such as irradiation, organ explantation, and antibody‐antigen reactions, are mentioned. The reactions to injury of mammalian foetal nerve tissue are reviewed. The severed spinal cord does not regenerate under ordinary circumstances in postnatal or foetal animals. Spinal ganglion cells regenerate. The reactions of the nervous system to injury are more extensive in younger foetuses than in older ones, and more marked in foetuses than in postnatal animals. This is seen in the results of eye extirpation in guinea‐pig foetuses compared with those in newborn rats. Gliosis is limited in foetal and young animals, and is not so marked in young foetuses as in old ones, owing probably to the immaturity of the neuroglial cells and to a relatively reduced glial cell number. The life history of nerve cells can be divided into three stages: the phase of proliferation, the phase of differentiation, and the phase of maturation, including growth and the completion and maintenance of this process. The methods of determining which stage of development of neurones is affected after operation on a mammalian foetus are explained. There are many cases in chick and amphibian embryos where cellular hypoplasia after operation is caused by retrograde or transneuronal regression or degeneration of cells, and is a result of effects on the maintenance of neurones, rather than on their proliferation or differentiation. Cases of foetal malformations, such as lack of development of a limb or eye, are reviewed. The hypoplastic effects in these cases are reinterpreted and are seen to be due also to effects on the maintenance of neurones, not on their proliferation or differentiation. Experiments on limb or eye removal in foetuses are reviewed. The resulting hypoplasia or surmised hypoplasia in the spinal ganglia, spinal cord, superior col‐liculus and lateral geniculate body are caused partly by retrograde or transneuronal degeneration or regression and are interpreted as effects, at least in part, on the maintenance of neurones. More work must be done on mammals before effects on proliferation and differentiation of neurones can be eliminated as contributing to hypoplasia after operation. The mammalian foetal experiments which produce hypoplasia after some or all of the nerve fibres have already reached their destination (limb, spinal cord, superior colliculus, lateral geniculate body) are not unlike many experiments producing hypoplastic effects in amphibian and chick embryos, where the nerve fibres have not yet innervated their respective parts at the time of operation. In both, the resulting hypoplasia is due, at least in part, to retrograde or transneuronal degeneration or regression of already differentiated nerve cells; it is frequently a direct effect on the maintenance of cells, rather than an indirect effect on proliferation or differentiation, and...

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Section: Reactions Of the Nervous System To Peripheral Changes In mentioning

confidence: 99%

The Experimental Embryology of the Foetal Nervous System

Hess

1957

Biological Reviews

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Effects of eye removal at birth on histogenesis of the mouse superior colliculus: An autoradiographic analysis with tritiated thymidine

1962

J of Comparative Neurology

131

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Neurogenesis in the optic tectum of larval Rana pipiens following unilateral enucleation

Eichler

1971

J of Comparative Neurology

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DNA synthesis and interlayer migrations of cells in the optic tectum of larval Rana pipiens were investigated, using several series of larvae which had been subjected to unilateral enucleation at stage 25, the last embryonic stage. It has been found that DNA synthesis occurs in all cellular layers of the tectum with least activity in peripheral layers. The location of the most active DNA synthesis during the larval period is the same as the location of cell division in the larval tectum, namely, in the layers bordering the ventricle of the optic lobe.Unilateral enucleation of stage 25 embryos results in a decrease in DNA synthesis in all cellular layers of the optic tectum contralateral to the operation when compared to the corresponding layers in the ipsilateral tectum. The differences in rate of incorporation of 3H-thymidine between the control and affected lobes become greater during development. Fewer cells are found in each layer of the affected larval tectum than in the corresponding layer of the control tectum. The decrease is greatest in more peripheral layers, whose cells are more intimately associated with the visual circuit than are cells of the deeper layers. Peripheral to layers 1 and 2, the percentages of labeled cells found in each layer are very similar on the two sides, suggesting common factors which control migration. Differences in cell number, therefore, reflect differential cell production rather than differential cell migrations.The distribution of label resulting from 3H-thymidine incorporation at stage TI1indicates that the distribution of mitotic activity is not uniform in the cephalocaudal axis of the tectum. Greater cell proliferation occurs in the posterior portion of the tectum than in the anterior region throughout larval development.The peripheral control of mitotic divisions in the frog optic tectum remains unknown. The data in the present study, however, support the hypothesis that influences from afferent fibers of the optic tract modify the rates or timing of DNA synthesis in the optic tectum. The data support the notion that the deepest tectal cells respond earliest to the stimulus and these may be ependymal cells which have processes extending to the outer surface of the tectum.Since early in this century investigators have been concerned with the influences that extramedullary factors and peripheral fields have upon the developing central nervous system. The earliest investigators, Steinitz ('06), Braus ('06), Shorey ('09), and Durken ('11, '13), demonstrated that if the size of the periphery were altered by experimental means, the size of the central nervous centers connecting these areas was likewise altered. It has since been clearly established that a larger than normal periphery connected to a nerve center

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The development of the optic lobes in Xenopus laevis. The effect of repeated crushing of the optic nerve

Cited by 22 publications

References 21 publications

The Experimental Embryology of the Foetal Nervous System

The Experimental Embryology of the Foetal Nervous System

Effects of eye removal at birth on histogenesis of the mouse superior colliculus: An autoradiographic analysis with tritiated thymidine

Neurogenesis in the optic tectum of larval Rana pipiens following unilateral enucleation

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