Beamish, Neal Gareth; (1991) A freeze-fracture electron microscope study on peripheral nerve in human diabetes mellitus and experimental protein deprivation. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The freeze-fracture replication technique was used to investigate the internal membrane structure in peripheral nerve in human diabetes mellitus and experimental protein deprivation. Qualitative and quantitative observations were made on the perineurium and the nerve fibres (axolemma and myelin). The perineurium in the normal human and rat sural nerve showed a wide range of P-face intramembranous particle (IMP) density, and considerable differences in the density of P-face IMPS between different perineurial lamellae. In the human diabetic perineurium, some of the tight junctions showed an abnormal organization, with bulge-like distortions in the junctional membrane and areas with fragmented and disarranged junctional components. There was also a significant reduction in the median density of P- face IMPs. Some of the perineurial tight junctions in older protein deprived rats showed focal regions of dispersed junctional components, and there was a significant increase in the median density of caveolae. The observations on the P-face IMPs in the perineurium suggest that different degrees of differentiation occur in the perineurial lamellae. The results also indicate that some, or all, of the perineurial cells may have structurally polarized membranes. The disorganized perineurial tight junctions in the diabetic human sural nerve may reflect a defect in the barrier function of this tissue. Some of the alterations resemble changes that have been produced experimentally in epithelial tight junctions by osmotic damage. It is considered, therefore, that similar mechanisms may have altered the perineurial tight junctions in human diabetes. The abnormal focal regions in the perineurial tight junctions in the older protein deprived rats may be responsible for the permeability defect in this tissue in malnutrition. The increase in the density of perineurial caveolae in the older protein deprived rats may indicate that the vesicles have a transport function, and that they are also capable of influencing the barrier function of the perineurium.

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