Summary
An attempt was made systematically to produce ectopic cells in the cerebellar molecular layer by means of X-irradiation. The influence of the age of the animal at the time of irradiation and the dose of X-rays, was studied. Based on the results and on data from the literature, a hypothesis is put forward as to the mechanism involved. It is suggested that partial destruction of one of the cerebellar matrices is followed by regeneration, which results in a de-synchronization of the morphogenetic events. As a consequence, a numerical mismatching occurs between the ingrowing mossy fibres and the descending granule cells, leading to invasion of the molecular layer by some of the mossy fibres and the formation of ectopic synapses. Dose- and age-dependency of the results of X-irradiation are in agreement with deductions from this hypothesis.
Similar mechanisms may well be involved in the pathogenesis of other developmental abnormalities of the central nervous system.
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This research was supported by Atomic Energy Commission research grant no AT (11-1)-2000 to Prof. Joseph Altman, Purdue University.
The investigations described were carried out while on leave from Groningen University.
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Ebels, E.J. Studies on ectopic granule cells in the cerebellar cortex —with a hypothesis as to their aetiology and pathogenesis. Acta Neuropathol 21, 117–127 (1972). https://doi.org/10.1007/BF00687566
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DOI: https://doi.org/10.1007/BF00687566