In this study, we have evaluated the capacity of recombimorphological profiles of transduced cells were consistnant adeno-associated virus (rAAV) vectors, containing cell ently neuronal, and there was no evidence of transgene type-specific promoters, to transduce neurons in vivo in the expression in glial elements. Transduction efficiencies for normal adult rat spinal cord. The neuron-specific enolase the NSE and PDGF rAAVs were estimated at 15 and 45 (NSE) promoter and the platelet-derived growth factor infectious particles per GFP-positive neuron, respectively, (PDGF) B-chain promoter were used to direct expression in the absence of detectable adenovirus. This study of a 'humanized' form of the gene for green fluorescent strongly supports a role for rAAV vectors in CNS gene therprotein (GFP). Neuron-specific rAAVs were injected into apy and lays the groundwork for delivery of more functional the mid-cervical regions of adult rat spinal cords. At genes to spinal cord neurons as a possible way to enhance 10-14 days, expression was detected in all animals and spinal cord repair following injury. persisted for up to 15 weeks. Immunocytochemical and

The distribution of interlamellar tight junctions was examined in myelin sheaths of Xenopus tadpole optic nerve and rabbit epiretinal tissue fixed with aldehydes, postfixed with osmium ferrocyanide and embedded in a water-soluble medium, Durcupan. Intramyelinic zonulae occludentes were clearly formed by fusion of adjacent intraperiod lines which corresponded to the external leaflets of oligodendrocytes. These occurred in register with other tight junctions present within successive lamellae and appeared as a series of radial lines extending either partially or totally across the thickness of the myelin sheath. This distribution of zonulae occludentes corresponded with that of tight junctional particle strands observed in freeze-fracture replicas. Analysis of intramyelinic vacuolation induced by hexachlorophene (HCP) intoxication indicated that lamellar splitting was frequently limited by the tight junctions. The intramyelinic zonulae occludentes also restricted the diffusion of colloidal lanthanum which had penetrated the myelin intraperiod gap following in vivo perineural injection. The results of this study provide evidence favouring a correspondence between interlamellar tight junctions and the 'radial component' of myelin described earlier by other investigators. Furthermore, observations of swollen myelin sheaths, resulting from HCP intoxication, suggest that these junctions may play a major role in maintaining myelin sheath integrity and limiting the extent of breakdown during certain pathological conditions.

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