1. Figure 1 Pathogenesis of diabetic neuropathy
Figure 1 | Pathogenesis of diabetic neuropathy. Diabetic neuropathy has a complex pathogenesis involving interaction of axonopathy, schwannopathy and microvasculopathy. The figure shows the anatomical organization of myelinated and unmyelinated axons within nerve fascicles. Their nutrient supply is secured via endoneurial capillaries which, together with the perineurial membrane, form the blood–nerve barrier. a | Human skin biopsy samples immunostained with PGP9.5 to show progression of peripheral nerves from the dermis into the epidermis, where they exist as small unmyelinated C-fibres (scale bar 40 µm). Left panel shows loss of fibres in a patient with diabetic neuropathy and right panel shows fibres in a healthy individual. b | Changes in axons and myelin in diabetic neuropathy, showing degeneration of Schwann cells and nerve fibres, culminating in nerve and intraepidermal fibre loss. c | Endoneurial capillaries from patients with diabetes. Top panel shows a capillary from a patient without diabetic neuropathy, and bottom panel shows a capillary from a patient with neuropathy, in which endothelial cell hyperplasia and basement membrane thickening have reduced the size of the capillary lumen. d | Narrowing of individual capillaries might not prevent blood from passing through the endoneurial capillary bed per se, but the resulting increase in velocity of blood through endoneurial functional shunts or epineurial arteriovenous shunts prevents efficient oxygen extraction, causing hypoxia. Panel a courtesy of Dr Páll Karlsson, Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Denmark.
Panel a courtesy of Dr Páll Karlsson, Danish Pain Research Center, Department of Clinical Medicine, Aarhus University, Denmark.
Gonçalves, N. P. et al. (2017) Schwann cell interactions with axons and microvessels in diabetic neuropathy
Nat. Rev. Neurol. doi: /nrneurol