ISSN:
1573-7381
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary When fragments of adult superior cervical ganglion (SCG) were transplanted to the undamaged surface of the cerebellum of 6–14-day-old rats, a series of remarkable changes ensued that were apparent during the postoperative periods of three weeks to two years: external granule cells were either arrested at the brain surface in the form of ectopic laminae, or migrated anomalously out of the brain to invade the SCG graft. Not only were granule cells so affected, but other interneurons, such as basket and stellate cells as well. The associated neuropil itself became displaced. Thus, mossy fibre boutons formed synaptic glomeruli with dendrites of arrested granule cells at the cerebellar surface. Reactive astrocytes, forming either thin parallel sheets or thick processes, and packed with filaments, mingled closely with the arrested neurons; typical Bergmann glia were not observed. Extensive bridges from the cerebellum to the SCG contained not only synaptically mature interneurons but also rows of parallel fibres, mossy fibres forming mini-glomeruli with solitary granule cells, and reactive astroglia. Portions of the Purkinje arbor extended into the tissue bridges and received synapses on elongate spines from co-migrating parallel fibres. Astroglial cells received synapse-like contacts on their somata and processes. Similar CG grafts induced tissue bridges, predominantly astroglial, to arise from the area postrema or dorsal medulla and enter the graft. Control transplantations tested the specificity of these cellular reactions. Other tissue grafts included muscle, salivary gland and normal or pre-degenerated sciatic nerve. Only direct allografts of sciatic nerve appeared to cause displacement of scattered granule cells. Non-biological grafts such as dacron, silicone and polystyrene, while causing mechanical deformation and inflammation, did not alter normal granule cell migration. The anomalously migrating neurons and neuropil, which seem to have by-passed certain patterns of cellular development, may respond positively to some diffusible tropic substances. The further determination of certain influences that may elicit these unique tissue-tissue interactions, suggested in the framework of this study to be components of neural regeneration or degeneration, could elucidate some aspects of neuronal interactions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01262412
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