ISSN:
1432-0533
Keywords:
Axonal regeneration
;
Peripheral nerve
;
Retrograde axonal transport
;
Vascular permeability
;
Endoneurium
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary It is well known that the ends of normal axons can absorb exogenous tracer proteins, which are then transported intra-axonally to the neuronal perikarya. The object of this investigation was to determine whether the same phenomenon occurs in regenerating nerve fibres. Horseradish peroxidase (HRP) was applied to the hypoglossal nerves of rats immediately or at intervals of 12 h to 14 days after crushing. The enzyme was detected histochemically, 24 h later, in the neurones of the hypoglossal nucleus. The numbers of HRP-containing neurones declined abruptly after the 4th postoperative day. By this time most of the regenerating axons extended further distally in the nerve than the region permeated by the topically applied HRP, though some growth cones were still present near the site of injury even after 14 days. It is deduced that the growing tips of the regenerating axons, but not their more proximal parts, absorbed HRP for subsequent retrograde transport to their cell bodies. In some of the rats a fluorescent tracer protein (thodamine B-labelled bovine serum albumin) was injected i.v. 1 h before death. Abnormal permeability of the endoneurial blood vessels was observed distal to the sites of crushing. The zone of increased permeability advanced distally at the same rate as that of the tips of the regenerating axons. It is suggested that the growth cones of regenerating axons may absorb proteins derived from the blood plasma. The retrograde axoplasmic transport of such substances to the cell bodies might be important in initiating and maintaining the neuronal metabolic changes necessary for the regeneration of severed axons.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00698271
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