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✯ Nerve bundle. Coloured scanning electron micrograph (SEM) of a freeze-fractured section through a bundle of myelinated nerve fibres. Myelin sheaths (yellow) can be seen surrounding the axons (blue). Perineurium (connective tissue, pink) surrounds the nerve bundle while endoneurium divides the individual fibres.✯
Myelinated nerves. Coloured scanning electron micrograph (SEM) of a section through the sciatic nerve, showing the myelinated nerve fibres (axons). Myelin (blue) is an insulating fatty layer that surrounds the nerve fibre (brown), increasing the speed at which nerve impulses travel. It is formed when Schwann cells wrap around the fibre, depositing layers of myelin between each coil. The outermost layer consists of the Schwann cell's cytoplasm and is known as the neurolemma or sheath of Schwann.
Optic nerve fibres. Coloured scanning electron micrograph (SEM) of axons from the optic nerve. Connective tissue fibres (thread-like) are also visible. The optic nerve visual information from the retina in the eye to the brain. Magnification: x2000 when printed at 10 centimetres wide.
A coloured scanning electron micrograph of a blueberry