The quantitation of nerve fibres in diabetic and transected sciatic nerves

Diabetes mellitus, a chronic metabolic disease, is a global problem affecting the economy, social life, and health. One of the most common complications of diabetes mellitus is diabetic neuropathy. Quantitative assessment of the effect on the peripheral nerves of diabetes is crucial to understanding the development and management of peripheral neuropathy. Unbiased stereological techniques are used to estimate the total number of myelinated and unmyelinated axons and the total area of the nerve fascicle in sciatic nerve cross-sections. Stereology is a mathematical and statistical method that permits the estimation of numerical data such as the volume, number, and length of three-dimensional biological structures using two-dimensional cross-sections. Axon number, myelin sheath thickness, and axon diameter parameters are widely used in the stereological examination of the sciatic nerve for evaluating regeneration and degeneration. In peripheral nerve analysis, axon counting is performed using the two-dimensional disector method, while myelin sheath thickness and axon diameter are estimated based on the nucleator method. The G-ratio value, the ratio of the inner axon area to the whole myelinated nerve fibre area, is essential in determining recovery after injury in the sciatic nerve. This chapter explains stereological methods of analysing the transected diabetic nerve based on an experimental diabetic rat model. It examines the general histological effects of diabetic neuropathy on the sciatic nerve using stereological methods.